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2 | Linux Ethernet Bonding Driver HOWTO |
3 | ||
ad246c99 | 4 | Latest update: 27 April 2011 |
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5 | |
6 | Initial release : Thomas Davis <tadavis at lbl.gov> | |
7 | Corrections, HA extensions : 2000/10/03-15 : | |
8 | - Willy Tarreau <willy at meta-x.org> | |
9 | - Constantine Gavrilov <const-g at xpert.com> | |
10 | - Chad N. Tindel <ctindel at ieee dot org> | |
11 | - Janice Girouard <girouard at us dot ibm dot com> | |
12 | - Jay Vosburgh <fubar at us dot ibm dot com> | |
13 | ||
14 | Reorganized and updated Feb 2005 by Jay Vosburgh | |
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15 | Added Sysfs information: 2006/04/24 |
16 | - Mitch Williams <mitch.a.williams at intel.com> | |
1da177e4 | 17 | |
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18 | Introduction |
19 | ============ | |
20 | ||
21 | The Linux bonding driver provides a method for aggregating | |
22 | multiple network interfaces into a single logical "bonded" interface. | |
23 | The behavior of the bonded interfaces depends upon the mode; generally | |
24 | speaking, modes provide either hot standby or load balancing services. | |
25 | Additionally, link integrity monitoring may be performed. | |
1da177e4 | 26 | |
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27 | The bonding driver originally came from Donald Becker's |
28 | beowulf patches for kernel 2.0. It has changed quite a bit since, and | |
29 | the original tools from extreme-linux and beowulf sites will not work | |
30 | with this version of the driver. | |
1da177e4 | 31 | |
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32 | For new versions of the driver, updated userspace tools, and |
33 | who to ask for help, please follow the links at the end of this file. | |
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34 | |
35 | Table of Contents | |
36 | ================= | |
37 | ||
38 | 1. Bonding Driver Installation | |
39 | ||
40 | 2. Bonding Driver Options | |
41 | ||
42 | 3. Configuring Bonding Devices | |
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43 | 3.1 Configuration with Sysconfig Support |
44 | 3.1.1 Using DHCP with Sysconfig | |
45 | 3.1.2 Configuring Multiple Bonds with Sysconfig | |
46 | 3.2 Configuration with Initscripts Support | |
47 | 3.2.1 Using DHCP with Initscripts | |
48 | 3.2.2 Configuring Multiple Bonds with Initscripts | |
49 | 3.3 Configuring Bonding Manually with Ifenslave | |
00354cfb | 50 | 3.3.1 Configuring Multiple Bonds Manually |
6224e01d | 51 | 3.4 Configuring Bonding Manually via Sysfs |
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52 | 3.5 Configuration with Interfaces Support |
53 | 3.6 Overriding Configuration for Special Cases | |
d22a5fc0 | 54 | 3.7 Configuring LACP for 802.3ad mode in a more secure way |
1da177e4 | 55 | |
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56 | 4. Querying Bonding Configuration |
57 | 4.1 Bonding Configuration | |
58 | 4.2 Network Configuration | |
1da177e4 | 59 | |
6224e01d | 60 | 5. Switch Configuration |
1da177e4 | 61 | |
6224e01d | 62 | 6. 802.1q VLAN Support |
1da177e4 | 63 | |
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64 | 7. Link Monitoring |
65 | 7.1 ARP Monitor Operation | |
66 | 7.2 Configuring Multiple ARP Targets | |
67 | 7.3 MII Monitor Operation | |
1da177e4 | 68 | |
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69 | 8. Potential Trouble Sources |
70 | 8.1 Adventures in Routing | |
71 | 8.2 Ethernet Device Renaming | |
72 | 8.3 Painfully Slow Or No Failed Link Detection By Miimon | |
1da177e4 | 73 | |
6224e01d | 74 | 9. SNMP agents |
1da177e4 | 75 | |
6224e01d | 76 | 10. Promiscuous mode |
1da177e4 | 77 | |
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78 | 11. Configuring Bonding for High Availability |
79 | 11.1 High Availability in a Single Switch Topology | |
80 | 11.2 High Availability in a Multiple Switch Topology | |
81 | 11.2.1 HA Bonding Mode Selection for Multiple Switch Topology | |
82 | 11.2.2 HA Link Monitoring for Multiple Switch Topology | |
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84 | 12. Configuring Bonding for Maximum Throughput |
85 | 12.1 Maximum Throughput in a Single Switch Topology | |
86 | 12.1.1 MT Bonding Mode Selection for Single Switch Topology | |
87 | 12.1.2 MT Link Monitoring for Single Switch Topology | |
88 | 12.2 Maximum Throughput in a Multiple Switch Topology | |
89 | 12.2.1 MT Bonding Mode Selection for Multiple Switch Topology | |
90 | 12.2.2 MT Link Monitoring for Multiple Switch Topology | |
1da177e4 | 91 | |
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92 | 13. Switch Behavior Issues |
93 | 13.1 Link Establishment and Failover Delays | |
94 | 13.2 Duplicated Incoming Packets | |
1da177e4 | 95 | |
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96 | 14. Hardware Specific Considerations |
97 | 14.1 IBM BladeCenter | |
1da177e4 | 98 | |
6224e01d | 99 | 15. Frequently Asked Questions |
00354cfb | 100 | |
6224e01d | 101 | 16. Resources and Links |
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102 | |
103 | ||
104 | 1. Bonding Driver Installation | |
105 | ============================== | |
106 | ||
107 | Most popular distro kernels ship with the bonding driver | |
b1098bbe | 108 | already available as a module. If your distro does not, or you |
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109 | have need to compile bonding from source (e.g., configuring and |
110 | installing a mainline kernel from kernel.org), you'll need to perform | |
111 | the following steps: | |
112 | ||
113 | 1.1 Configure and build the kernel with bonding | |
114 | ----------------------------------------------- | |
115 | ||
00354cfb | 116 | The current version of the bonding driver is available in the |
1da177e4 | 117 | drivers/net/bonding subdirectory of the most recent kernel source |
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118 | (which is available on http://kernel.org). Most users "rolling their |
119 | own" will want to use the most recent kernel from kernel.org. | |
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120 | |
121 | Configure kernel with "make menuconfig" (or "make xconfig" or | |
122 | "make config"), then select "Bonding driver support" in the "Network | |
123 | device support" section. It is recommended that you configure the | |
124 | driver as module since it is currently the only way to pass parameters | |
125 | to the driver or configure more than one bonding device. | |
126 | ||
b1098bbe | 127 | Build and install the new kernel and modules. |
1da177e4 | 128 | |
b1098bbe | 129 | 1.2 Bonding Control Utility |
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130 | ------------------------------------- |
131 | ||
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132 | It is recommended to configure bonding via iproute2 (netlink) |
133 | or sysfs, the old ifenslave control utility is obsolete. | |
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134 | |
135 | 2. Bonding Driver Options | |
136 | ========================= | |
137 | ||
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138 | Options for the bonding driver are supplied as parameters to the |
139 | bonding module at load time, or are specified via sysfs. | |
140 | ||
141 | Module options may be given as command line arguments to the | |
142 | insmod or modprobe command, but are usually specified in either the | |
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143 | /etc/modrobe.d/*.conf configuration files, or in a distro-specific |
144 | configuration file (some of which are detailed in the next section). | |
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145 | |
146 | Details on bonding support for sysfs is provided in the | |
147 | "Configuring Bonding Manually via Sysfs" section, below. | |
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148 | |
149 | The available bonding driver parameters are listed below. If a | |
150 | parameter is not specified the default value is used. When initially | |
151 | configuring a bond, it is recommended "tail -f /var/log/messages" be | |
152 | run in a separate window to watch for bonding driver error messages. | |
153 | ||
154 | It is critical that either the miimon or arp_interval and | |
155 | arp_ip_target parameters be specified, otherwise serious network | |
156 | degradation will occur during link failures. Very few devices do not | |
157 | support at least miimon, so there is really no reason not to use it. | |
158 | ||
159 | Options with textual values will accept either the text name | |
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160 | or, for backwards compatibility, the option value. E.g., |
161 | "mode=802.3ad" and "mode=4" set the same mode. | |
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162 | |
163 | The parameters are as follows: | |
164 | ||
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165 | active_slave |
166 | ||
167 | Specifies the new active slave for modes that support it | |
168 | (active-backup, balance-alb and balance-tlb). Possible values | |
169 | are the name of any currently enslaved interface, or an empty | |
170 | string. If a name is given, the slave and its link must be up in order | |
171 | to be selected as the new active slave. If an empty string is | |
172 | specified, the current active slave is cleared, and a new active | |
173 | slave is selected automatically. | |
174 | ||
175 | Note that this is only available through the sysfs interface. No module | |
176 | parameter by this name exists. | |
177 | ||
178 | The normal value of this option is the name of the currently | |
179 | active slave, or the empty string if there is no active slave or | |
180 | the current mode does not use an active slave. | |
181 | ||
6791e466 MB |
182 | ad_actor_sys_prio |
183 | ||
184 | In an AD system, this specifies the system priority. The allowed range | |
185 | is 1 - 65535. If the value is not specified, it takes 65535 as the | |
186 | default value. | |
187 | ||
188 | This parameter has effect only in 802.3ad mode and is available through | |
189 | SysFs interface. | |
190 | ||
74514957 MB |
191 | ad_actor_system |
192 | ||
193 | In an AD system, this specifies the mac-address for the actor in | |
194 | protocol packet exchanges (LACPDUs). The value cannot be NULL or | |
195 | multicast. It is preferred to have the local-admin bit set for this | |
196 | mac but driver does not enforce it. If the value is not given then | |
197 | system defaults to using the masters' mac address as actors' system | |
198 | address. | |
199 | ||
200 | This parameter has effect only in 802.3ad mode and is available through | |
201 | SysFs interface. | |
202 | ||
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203 | ad_select |
204 | ||
205 | Specifies the 802.3ad aggregation selection logic to use. The | |
206 | possible values and their effects are: | |
207 | ||
208 | stable or 0 | |
209 | ||
210 | The active aggregator is chosen by largest aggregate | |
211 | bandwidth. | |
212 | ||
213 | Reselection of the active aggregator occurs only when all | |
214 | slaves of the active aggregator are down or the active | |
215 | aggregator has no slaves. | |
216 | ||
217 | This is the default value. | |
218 | ||
219 | bandwidth or 1 | |
220 | ||
221 | The active aggregator is chosen by largest aggregate | |
222 | bandwidth. Reselection occurs if: | |
223 | ||
224 | - A slave is added to or removed from the bond | |
225 | ||
226 | - Any slave's link state changes | |
227 | ||
228 | - Any slave's 802.3ad association state changes | |
229 | ||
19f59460 | 230 | - The bond's administrative state changes to up |
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231 | |
232 | count or 2 | |
233 | ||
234 | The active aggregator is chosen by the largest number of | |
235 | ports (slaves). Reselection occurs as described under the | |
236 | "bandwidth" setting, above. | |
237 | ||
238 | The bandwidth and count selection policies permit failover of | |
239 | 802.3ad aggregations when partial failure of the active aggregator | |
240 | occurs. This keeps the aggregator with the highest availability | |
241 | (either in bandwidth or in number of ports) active at all times. | |
242 | ||
243 | This option was added in bonding version 3.4.0. | |
244 | ||
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245 | ad_user_port_key |
246 | ||
247 | In an AD system, the port-key has three parts as shown below - | |
248 | ||
249 | Bits Use | |
250 | 00 Duplex | |
251 | 01-05 Speed | |
252 | 06-15 User-defined | |
253 | ||
254 | This defines the upper 10 bits of the port key. The values can be | |
255 | from 0 - 1023. If not given, the system defaults to 0. | |
256 | ||
257 | This parameter has effect only in 802.3ad mode and is available through | |
258 | SysFs interface. | |
259 | ||
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260 | all_slaves_active |
261 | ||
262 | Specifies that duplicate frames (received on inactive ports) should be | |
263 | dropped (0) or delivered (1). | |
264 | ||
265 | Normally, bonding will drop duplicate frames (received on inactive | |
266 | ports), which is desirable for most users. But there are some times | |
267 | it is nice to allow duplicate frames to be delivered. | |
268 | ||
269 | The default value is 0 (drop duplicate frames received on inactive | |
270 | ports). | |
271 | ||
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272 | arp_interval |
273 | ||
00354cfb | 274 | Specifies the ARP link monitoring frequency in milliseconds. |
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275 | |
276 | The ARP monitor works by periodically checking the slave | |
277 | devices to determine whether they have sent or received | |
278 | traffic recently (the precise criteria depends upon the | |
279 | bonding mode, and the state of the slave). Regular traffic is | |
280 | generated via ARP probes issued for the addresses specified by | |
281 | the arp_ip_target option. | |
282 | ||
283 | This behavior can be modified by the arp_validate option, | |
284 | below. | |
285 | ||
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286 | If ARP monitoring is used in an etherchannel compatible mode |
287 | (modes 0 and 2), the switch should be configured in a mode | |
288 | that evenly distributes packets across all links. If the | |
289 | switch is configured to distribute the packets in an XOR | |
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290 | fashion, all replies from the ARP targets will be received on |
291 | the same link which could cause the other team members to | |
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292 | fail. ARP monitoring should not be used in conjunction with |
293 | miimon. A value of 0 disables ARP monitoring. The default | |
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294 | value is 0. |
295 | ||
296 | arp_ip_target | |
297 | ||
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298 | Specifies the IP addresses to use as ARP monitoring peers when |
299 | arp_interval is > 0. These are the targets of the ARP request | |
300 | sent to determine the health of the link to the targets. | |
301 | Specify these values in ddd.ddd.ddd.ddd format. Multiple IP | |
302 | addresses must be separated by a comma. At least one IP | |
303 | address must be given for ARP monitoring to function. The | |
304 | maximum number of targets that can be specified is 16. The | |
305 | default value is no IP addresses. | |
1da177e4 | 306 | |
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307 | arp_validate |
308 | ||
309 | Specifies whether or not ARP probes and replies should be | |
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310 | validated in any mode that supports arp monitoring, or whether |
311 | non-ARP traffic should be filtered (disregarded) for link | |
312 | monitoring purposes. | |
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313 | |
314 | Possible values are: | |
315 | ||
316 | none or 0 | |
317 | ||
52f65ef3 | 318 | No validation or filtering is performed. |
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319 | |
320 | active or 1 | |
321 | ||
322 | Validation is performed only for the active slave. | |
323 | ||
324 | backup or 2 | |
325 | ||
326 | Validation is performed only for backup slaves. | |
327 | ||
328 | all or 3 | |
329 | ||
330 | Validation is performed for all slaves. | |
331 | ||
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332 | filter or 4 |
333 | ||
334 | Filtering is applied to all slaves. No validation is | |
335 | performed. | |
336 | ||
337 | filter_active or 5 | |
338 | ||
339 | Filtering is applied to all slaves, validation is performed | |
340 | only for the active slave. | |
341 | ||
342 | filter_backup or 6 | |
343 | ||
344 | Filtering is applied to all slaves, validation is performed | |
345 | only for backup slaves. | |
346 | ||
347 | Validation: | |
348 | ||
349 | Enabling validation causes the ARP monitor to examine the incoming | |
350 | ARP requests and replies, and only consider a slave to be up if it | |
351 | is receiving the appropriate ARP traffic. | |
352 | ||
353 | For an active slave, the validation checks ARP replies to confirm | |
354 | that they were generated by an arp_ip_target. Since backup slaves | |
355 | do not typically receive these replies, the validation performed | |
356 | for backup slaves is on the broadcast ARP request sent out via the | |
357 | active slave. It is possible that some switch or network | |
358 | configurations may result in situations wherein the backup slaves | |
359 | do not receive the ARP requests; in such a situation, validation | |
360 | of backup slaves must be disabled. | |
361 | ||
362 | The validation of ARP requests on backup slaves is mainly helping | |
363 | bonding to decide which slaves are more likely to work in case of | |
364 | the active slave failure, it doesn't really guarantee that the | |
365 | backup slave will work if it's selected as the next active slave. | |
366 | ||
367 | Validation is useful in network configurations in which multiple | |
368 | bonding hosts are concurrently issuing ARPs to one or more targets | |
369 | beyond a common switch. Should the link between the switch and | |
370 | target fail (but not the switch itself), the probe traffic | |
371 | generated by the multiple bonding instances will fool the standard | |
372 | ARP monitor into considering the links as still up. Use of | |
373 | validation can resolve this, as the ARP monitor will only consider | |
374 | ARP requests and replies associated with its own instance of | |
375 | bonding. | |
376 | ||
377 | Filtering: | |
378 | ||
379 | Enabling filtering causes the ARP monitor to only use incoming ARP | |
380 | packets for link availability purposes. Arriving packets that are | |
381 | not ARPs are delivered normally, but do not count when determining | |
382 | if a slave is available. | |
383 | ||
384 | Filtering operates by only considering the reception of ARP | |
385 | packets (any ARP packet, regardless of source or destination) when | |
386 | determining if a slave has received traffic for link availability | |
387 | purposes. | |
388 | ||
389 | Filtering is useful in network configurations in which significant | |
390 | levels of third party broadcast traffic would fool the standard | |
391 | ARP monitor into considering the links as still up. Use of | |
392 | filtering can resolve this, as only ARP traffic is considered for | |
393 | link availability purposes. | |
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394 | |
395 | This option was added in bonding version 3.1.0. | |
396 | ||
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397 | arp_all_targets |
398 | ||
399 | Specifies the quantity of arp_ip_targets that must be reachable | |
400 | in order for the ARP monitor to consider a slave as being up. | |
401 | This option affects only active-backup mode for slaves with | |
402 | arp_validation enabled. | |
403 | ||
404 | Possible values are: | |
405 | ||
406 | any or 0 | |
407 | ||
408 | consider the slave up only when any of the arp_ip_targets | |
409 | is reachable | |
410 | ||
411 | all or 1 | |
412 | ||
413 | consider the slave up only when all of the arp_ip_targets | |
414 | are reachable | |
415 | ||
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416 | downdelay |
417 | ||
418 | Specifies the time, in milliseconds, to wait before disabling | |
419 | a slave after a link failure has been detected. This option | |
420 | is only valid for the miimon link monitor. The downdelay | |
421 | value should be a multiple of the miimon value; if not, it | |
422 | will be rounded down to the nearest multiple. The default | |
423 | value is 0. | |
424 | ||
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425 | fail_over_mac |
426 | ||
427 | Specifies whether active-backup mode should set all slaves to | |
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428 | the same MAC address at enslavement (the traditional |
429 | behavior), or, when enabled, perform special handling of the | |
430 | bond's MAC address in accordance with the selected policy. | |
431 | ||
432 | Possible values are: | |
433 | ||
434 | none or 0 | |
435 | ||
436 | This setting disables fail_over_mac, and causes | |
437 | bonding to set all slaves of an active-backup bond to | |
438 | the same MAC address at enslavement time. This is the | |
439 | default. | |
440 | ||
441 | active or 1 | |
442 | ||
443 | The "active" fail_over_mac policy indicates that the | |
444 | MAC address of the bond should always be the MAC | |
445 | address of the currently active slave. The MAC | |
446 | address of the slaves is not changed; instead, the MAC | |
447 | address of the bond changes during a failover. | |
448 | ||
449 | This policy is useful for devices that cannot ever | |
450 | alter their MAC address, or for devices that refuse | |
451 | incoming broadcasts with their own source MAC (which | |
452 | interferes with the ARP monitor). | |
453 | ||
454 | The down side of this policy is that every device on | |
455 | the network must be updated via gratuitous ARP, | |
456 | vs. just updating a switch or set of switches (which | |
457 | often takes place for any traffic, not just ARP | |
458 | traffic, if the switch snoops incoming traffic to | |
459 | update its tables) for the traditional method. If the | |
460 | gratuitous ARP is lost, communication may be | |
461 | disrupted. | |
462 | ||
25985edc | 463 | When this policy is used in conjunction with the mii |
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464 | monitor, devices which assert link up prior to being |
465 | able to actually transmit and receive are particularly | |
19f59460 | 466 | susceptible to loss of the gratuitous ARP, and an |
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467 | appropriate updelay setting may be required. |
468 | ||
469 | follow or 2 | |
470 | ||
471 | The "follow" fail_over_mac policy causes the MAC | |
472 | address of the bond to be selected normally (normally | |
473 | the MAC address of the first slave added to the bond). | |
474 | However, the second and subsequent slaves are not set | |
475 | to this MAC address while they are in a backup role; a | |
476 | slave is programmed with the bond's MAC address at | |
477 | failover time (and the formerly active slave receives | |
478 | the newly active slave's MAC address). | |
479 | ||
480 | This policy is useful for multiport devices that | |
481 | either become confused or incur a performance penalty | |
482 | when multiple ports are programmed with the same MAC | |
483 | address. | |
484 | ||
485 | ||
486 | The default policy is none, unless the first slave cannot | |
487 | change its MAC address, in which case the active policy is | |
488 | selected by default. | |
489 | ||
490 | This option may be modified via sysfs only when no slaves are | |
491 | present in the bond. | |
492 | ||
493 | This option was added in bonding version 3.2.0. The "follow" | |
494 | policy was added in bonding version 3.3.0. | |
dd957c57 | 495 | |
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496 | lacp_rate |
497 | ||
498 | Option specifying the rate in which we'll ask our link partner | |
499 | to transmit LACPDU packets in 802.3ad mode. Possible values | |
500 | are: | |
501 | ||
502 | slow or 0 | |
00354cfb | 503 | Request partner to transmit LACPDUs every 30 seconds |
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504 | |
505 | fast or 1 | |
506 | Request partner to transmit LACPDUs every 1 second | |
507 | ||
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508 | The default is slow. |
509 | ||
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510 | max_bonds |
511 | ||
512 | Specifies the number of bonding devices to create for this | |
513 | instance of the bonding driver. E.g., if max_bonds is 3, and | |
514 | the bonding driver is not already loaded, then bond0, bond1 | |
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515 | and bond2 will be created. The default value is 1. Specifying |
516 | a value of 0 will load bonding, but will not create any devices. | |
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517 | |
518 | miimon | |
519 | ||
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520 | Specifies the MII link monitoring frequency in milliseconds. |
521 | This determines how often the link state of each slave is | |
522 | inspected for link failures. A value of zero disables MII | |
523 | link monitoring. A value of 100 is a good starting point. | |
524 | The use_carrier option, below, affects how the link state is | |
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525 | determined. See the High Availability section for additional |
526 | information. The default value is 0. | |
527 | ||
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528 | min_links |
529 | ||
530 | Specifies the minimum number of links that must be active before | |
531 | asserting carrier. It is similar to the Cisco EtherChannel min-links | |
532 | feature. This allows setting the minimum number of member ports that | |
533 | must be up (link-up state) before marking the bond device as up | |
534 | (carrier on). This is useful for situations where higher level services | |
535 | such as clustering want to ensure a minimum number of low bandwidth | |
536 | links are active before switchover. This option only affect 802.3ad | |
537 | mode. | |
538 | ||
539 | The default value is 0. This will cause carrier to be asserted (for | |
540 | 802.3ad mode) whenever there is an active aggregator, regardless of the | |
541 | number of available links in that aggregator. Note that, because an | |
542 | aggregator cannot be active without at least one available link, | |
543 | setting this option to 0 or to 1 has the exact same effect. | |
544 | ||
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545 | mode |
546 | ||
547 | Specifies one of the bonding policies. The default is | |
548 | balance-rr (round robin). Possible values are: | |
549 | ||
550 | balance-rr or 0 | |
551 | ||
552 | Round-robin policy: Transmit packets in sequential | |
553 | order from the first available slave through the | |
554 | last. This mode provides load balancing and fault | |
555 | tolerance. | |
556 | ||
557 | active-backup or 1 | |
558 | ||
559 | Active-backup policy: Only one slave in the bond is | |
560 | active. A different slave becomes active if, and only | |
561 | if, the active slave fails. The bond's MAC address is | |
562 | externally visible on only one port (network adapter) | |
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563 | to avoid confusing the switch. |
564 | ||
565 | In bonding version 2.6.2 or later, when a failover | |
566 | occurs in active-backup mode, bonding will issue one | |
567 | or more gratuitous ARPs on the newly active slave. | |
6224e01d | 568 | One gratuitous ARP is issued for the bonding master |
00354cfb JV |
569 | interface and each VLAN interfaces configured above |
570 | it, provided that the interface has at least one IP | |
571 | address configured. Gratuitous ARPs issued for VLAN | |
572 | interfaces are tagged with the appropriate VLAN id. | |
573 | ||
574 | This mode provides fault tolerance. The primary | |
575 | option, documented below, affects the behavior of this | |
576 | mode. | |
1da177e4 LT |
577 | |
578 | balance-xor or 2 | |
579 | ||
00354cfb JV |
580 | XOR policy: Transmit based on the selected transmit |
581 | hash policy. The default policy is a simple [(source | |
92abf750 JX |
582 | MAC address XOR'd with destination MAC address XOR |
583 | packet type ID) modulo slave count]. Alternate transmit | |
584 | policies may be selected via the xmit_hash_policy option, | |
585 | described below. | |
00354cfb JV |
586 | |
587 | This mode provides load balancing and fault tolerance. | |
1da177e4 LT |
588 | |
589 | broadcast or 3 | |
590 | ||
591 | Broadcast policy: transmits everything on all slave | |
592 | interfaces. This mode provides fault tolerance. | |
593 | ||
594 | 802.3ad or 4 | |
595 | ||
596 | IEEE 802.3ad Dynamic link aggregation. Creates | |
597 | aggregation groups that share the same speed and | |
598 | duplex settings. Utilizes all slaves in the active | |
599 | aggregator according to the 802.3ad specification. | |
600 | ||
00354cfb JV |
601 | Slave selection for outgoing traffic is done according |
602 | to the transmit hash policy, which may be changed from | |
603 | the default simple XOR policy via the xmit_hash_policy | |
604 | option, documented below. Note that not all transmit | |
605 | policies may be 802.3ad compliant, particularly in | |
606 | regards to the packet mis-ordering requirements of | |
607 | section 43.2.4 of the 802.3ad standard. Differing | |
608 | peer implementations will have varying tolerances for | |
609 | noncompliance. | |
610 | ||
611 | Prerequisites: | |
1da177e4 LT |
612 | |
613 | 1. Ethtool support in the base drivers for retrieving | |
614 | the speed and duplex of each slave. | |
615 | ||
616 | 2. A switch that supports IEEE 802.3ad Dynamic link | |
617 | aggregation. | |
618 | ||
619 | Most switches will require some type of configuration | |
620 | to enable 802.3ad mode. | |
621 | ||
622 | balance-tlb or 5 | |
623 | ||
624 | Adaptive transmit load balancing: channel bonding that | |
e9f0fb88 MB |
625 | does not require any special switch support. |
626 | ||
627 | In tlb_dynamic_lb=1 mode; the outgoing traffic is | |
628 | distributed according to the current load (computed | |
629 | relative to the speed) on each slave. | |
630 | ||
631 | In tlb_dynamic_lb=0 mode; the load balancing based on | |
632 | current load is disabled and the load is distributed | |
633 | only using the hash distribution. | |
634 | ||
635 | Incoming traffic is received by the current slave. | |
636 | If the receiving slave fails, another slave takes over | |
637 | the MAC address of the failed receiving slave. | |
1da177e4 LT |
638 | |
639 | Prerequisite: | |
640 | ||
641 | Ethtool support in the base drivers for retrieving the | |
642 | speed of each slave. | |
643 | ||
644 | balance-alb or 6 | |
645 | ||
646 | Adaptive load balancing: includes balance-tlb plus | |
647 | receive load balancing (rlb) for IPV4 traffic, and | |
648 | does not require any special switch support. The | |
649 | receive load balancing is achieved by ARP negotiation. | |
650 | The bonding driver intercepts the ARP Replies sent by | |
651 | the local system on their way out and overwrites the | |
652 | source hardware address with the unique hardware | |
653 | address of one of the slaves in the bond such that | |
654 | different peers use different hardware addresses for | |
655 | the server. | |
656 | ||
657 | Receive traffic from connections created by the server | |
658 | is also balanced. When the local system sends an ARP | |
659 | Request the bonding driver copies and saves the peer's | |
660 | IP information from the ARP packet. When the ARP | |
661 | Reply arrives from the peer, its hardware address is | |
662 | retrieved and the bonding driver initiates an ARP | |
663 | reply to this peer assigning it to one of the slaves | |
664 | in the bond. A problematic outcome of using ARP | |
665 | negotiation for balancing is that each time that an | |
666 | ARP request is broadcast it uses the hardware address | |
667 | of the bond. Hence, peers learn the hardware address | |
668 | of the bond and the balancing of receive traffic | |
669 | collapses to the current slave. This is handled by | |
670 | sending updates (ARP Replies) to all the peers with | |
671 | their individually assigned hardware address such that | |
672 | the traffic is redistributed. Receive traffic is also | |
673 | redistributed when a new slave is added to the bond | |
674 | and when an inactive slave is re-activated. The | |
675 | receive load is distributed sequentially (round robin) | |
676 | among the group of highest speed slaves in the bond. | |
677 | ||
678 | When a link is reconnected or a new slave joins the | |
679 | bond the receive traffic is redistributed among all | |
00354cfb | 680 | active slaves in the bond by initiating ARP Replies |
6224e01d | 681 | with the selected MAC address to each of the |
1da177e4 LT |
682 | clients. The updelay parameter (detailed below) must |
683 | be set to a value equal or greater than the switch's | |
684 | forwarding delay so that the ARP Replies sent to the | |
685 | peers will not be blocked by the switch. | |
686 | ||
687 | Prerequisites: | |
688 | ||
689 | 1. Ethtool support in the base drivers for retrieving | |
690 | the speed of each slave. | |
691 | ||
692 | 2. Base driver support for setting the hardware | |
693 | address of a device while it is open. This is | |
694 | required so that there will always be one slave in the | |
695 | team using the bond hardware address (the | |
696 | curr_active_slave) while having a unique hardware | |
697 | address for each slave in the bond. If the | |
698 | curr_active_slave fails its hardware address is | |
699 | swapped with the new curr_active_slave that was | |
700 | chosen. | |
701 | ||
b59f9f74 | 702 | num_grat_arp |
305d552a BH |
703 | num_unsol_na |
704 | ||
ad246c99 BH |
705 | Specify the number of peer notifications (gratuitous ARPs and |
706 | unsolicited IPv6 Neighbor Advertisements) to be issued after a | |
707 | failover event. As soon as the link is up on the new slave | |
708 | (possibly immediately) a peer notification is sent on the | |
709 | bonding device and each VLAN sub-device. This is repeated at | |
710 | each link monitor interval (arp_interval or miimon, whichever | |
711 | is active) if the number is greater than 1. | |
712 | ||
713 | The valid range is 0 - 255; the default value is 1. These options | |
714 | affect only the active-backup mode. These options were added for | |
715 | bonding versions 3.3.0 and 3.4.0 respectively. | |
716 | ||
8fb4e139 | 717 | From Linux 3.0 and bonding version 3.7.1, these notifications |
ad246c99 BH |
718 | are generated by the ipv4 and ipv6 code and the numbers of |
719 | repetitions cannot be set independently. | |
305d552a | 720 | |
12465fb8 NA |
721 | packets_per_slave |
722 | ||
723 | Specify the number of packets to transmit through a slave before | |
724 | moving to the next one. When set to 0 then a slave is chosen at | |
725 | random. | |
726 | ||
727 | The valid range is 0 - 65535; the default value is 1. This option | |
728 | has effect only in balance-rr mode. | |
729 | ||
1da177e4 LT |
730 | primary |
731 | ||
732 | A string (eth0, eth2, etc) specifying which slave is the | |
733 | primary device. The specified device will always be the | |
734 | active slave while it is available. Only when the primary is | |
735 | off-line will alternate devices be used. This is useful when | |
736 | one slave is preferred over another, e.g., when one slave has | |
737 | higher throughput than another. | |
738 | ||
e1d206a7 | 739 | The primary option is only valid for active-backup(1), |
740 | balance-tlb (5) and balance-alb (6) mode. | |
1da177e4 | 741 | |
a549952a JP |
742 | primary_reselect |
743 | ||
744 | Specifies the reselection policy for the primary slave. This | |
745 | affects how the primary slave is chosen to become the active slave | |
746 | when failure of the active slave or recovery of the primary slave | |
747 | occurs. This option is designed to prevent flip-flopping between | |
748 | the primary slave and other slaves. Possible values are: | |
749 | ||
750 | always or 0 (default) | |
751 | ||
752 | The primary slave becomes the active slave whenever it | |
753 | comes back up. | |
754 | ||
755 | better or 1 | |
756 | ||
757 | The primary slave becomes the active slave when it comes | |
758 | back up, if the speed and duplex of the primary slave is | |
759 | better than the speed and duplex of the current active | |
760 | slave. | |
761 | ||
762 | failure or 2 | |
763 | ||
764 | The primary slave becomes the active slave only if the | |
765 | current active slave fails and the primary slave is up. | |
766 | ||
767 | The primary_reselect setting is ignored in two cases: | |
768 | ||
769 | If no slaves are active, the first slave to recover is | |
770 | made the active slave. | |
771 | ||
772 | When initially enslaved, the primary slave is always made | |
773 | the active slave. | |
774 | ||
775 | Changing the primary_reselect policy via sysfs will cause an | |
776 | immediate selection of the best active slave according to the new | |
777 | policy. This may or may not result in a change of the active | |
778 | slave, depending upon the circumstances. | |
779 | ||
780 | This option was added for bonding version 3.6.0. | |
781 | ||
e9f0fb88 MB |
782 | tlb_dynamic_lb |
783 | ||
784 | Specifies if dynamic shuffling of flows is enabled in tlb | |
785 | mode. The value has no effect on any other modes. | |
786 | ||
787 | The default behavior of tlb mode is to shuffle active flows across | |
788 | slaves based on the load in that interval. This gives nice lb | |
789 | characteristics but can cause packet reordering. If re-ordering is | |
790 | a concern use this variable to disable flow shuffling and rely on | |
791 | load balancing provided solely by the hash distribution. | |
792 | xmit-hash-policy can be used to select the appropriate hashing for | |
793 | the setup. | |
794 | ||
795 | The sysfs entry can be used to change the setting per bond device | |
796 | and the initial value is derived from the module parameter. The | |
797 | sysfs entry is allowed to be changed only if the bond device is | |
798 | down. | |
799 | ||
800 | The default value is "1" that enables flow shuffling while value "0" | |
801 | disables it. This option was added in bonding driver 3.7.1 | |
802 | ||
803 | ||
1da177e4 LT |
804 | updelay |
805 | ||
806 | Specifies the time, in milliseconds, to wait before enabling a | |
807 | slave after a link recovery has been detected. This option is | |
808 | only valid for the miimon link monitor. The updelay value | |
809 | should be a multiple of the miimon value; if not, it will be | |
810 | rounded down to the nearest multiple. The default value is 0. | |
811 | ||
812 | use_carrier | |
813 | ||
814 | Specifies whether or not miimon should use MII or ETHTOOL | |
815 | ioctls vs. netif_carrier_ok() to determine the link | |
816 | status. The MII or ETHTOOL ioctls are less efficient and | |
817 | utilize a deprecated calling sequence within the kernel. The | |
818 | netif_carrier_ok() relies on the device driver to maintain its | |
819 | state with netif_carrier_on/off; at this writing, most, but | |
820 | not all, device drivers support this facility. | |
821 | ||
822 | If bonding insists that the link is up when it should not be, | |
823 | it may be that your network device driver does not support | |
824 | netif_carrier_on/off. The default state for netif_carrier is | |
825 | "carrier on," so if a driver does not support netif_carrier, | |
826 | it will appear as if the link is always up. In this case, | |
827 | setting use_carrier to 0 will cause bonding to revert to the | |
828 | MII / ETHTOOL ioctl method to determine the link state. | |
829 | ||
830 | A value of 1 enables the use of netif_carrier_ok(), a value of | |
831 | 0 will use the deprecated MII / ETHTOOL ioctls. The default | |
832 | value is 1. | |
833 | ||
00354cfb JV |
834 | xmit_hash_policy |
835 | ||
836 | Selects the transmit hash policy to use for slave selection in | |
f05b42ea | 837 | balance-xor, 802.3ad, and tlb modes. Possible values are: |
00354cfb JV |
838 | |
839 | layer2 | |
840 | ||
92abf750 JX |
841 | Uses XOR of hardware MAC addresses and packet type ID |
842 | field to generate the hash. The formula is | |
00354cfb | 843 | |
92abf750 JX |
844 | hash = source MAC XOR destination MAC XOR packet type ID |
845 | slave number = hash modulo slave count | |
00354cfb JV |
846 | |
847 | This algorithm will place all traffic to a particular | |
848 | network peer on the same slave. | |
849 | ||
850 | This algorithm is 802.3ad compliant. | |
851 | ||
6f6652be JV |
852 | layer2+3 |
853 | ||
854 | This policy uses a combination of layer2 and layer3 | |
855 | protocol information to generate the hash. | |
856 | ||
857 | Uses XOR of hardware MAC addresses and IP addresses to | |
7a6afab1 | 858 | generate the hash. The formula is |
6f6652be | 859 | |
92abf750 | 860 | hash = source MAC XOR destination MAC XOR packet type ID |
7a6afab1 NA |
861 | hash = hash XOR source IP XOR destination IP |
862 | hash = hash XOR (hash RSHIFT 16) | |
863 | hash = hash XOR (hash RSHIFT 8) | |
864 | And then hash is reduced modulo slave count. | |
6f6652be | 865 | |
7a6afab1 NA |
866 | If the protocol is IPv6 then the source and destination |
867 | addresses are first hashed using ipv6_addr_hash. | |
6b923cb7 | 868 | |
6f6652be JV |
869 | This algorithm will place all traffic to a particular |
870 | network peer on the same slave. For non-IP traffic, | |
871 | the formula is the same as for the layer2 transmit | |
872 | hash policy. | |
873 | ||
874 | This policy is intended to provide a more balanced | |
875 | distribution of traffic than layer2 alone, especially | |
876 | in environments where a layer3 gateway device is | |
877 | required to reach most destinations. | |
878 | ||
d9195881 | 879 | This algorithm is 802.3ad compliant. |
6f6652be | 880 | |
00354cfb JV |
881 | layer3+4 |
882 | ||
883 | This policy uses upper layer protocol information, | |
884 | when available, to generate the hash. This allows for | |
885 | traffic to a particular network peer to span multiple | |
886 | slaves, although a single connection will not span | |
887 | multiple slaves. | |
888 | ||
7a6afab1 | 889 | The formula for unfragmented TCP and UDP packets is |
00354cfb | 890 | |
7a6afab1 NA |
891 | hash = source port, destination port (as in the header) |
892 | hash = hash XOR source IP XOR destination IP | |
893 | hash = hash XOR (hash RSHIFT 16) | |
894 | hash = hash XOR (hash RSHIFT 8) | |
895 | And then hash is reduced modulo slave count. | |
6b923cb7 | 896 | |
7a6afab1 NA |
897 | If the protocol is IPv6 then the source and destination |
898 | addresses are first hashed using ipv6_addr_hash. | |
6b923cb7 JE |
899 | |
900 | For fragmented TCP or UDP packets and all other IPv4 and | |
901 | IPv6 protocol traffic, the source and destination port | |
00354cfb JV |
902 | information is omitted. For non-IP traffic, the |
903 | formula is the same as for the layer2 transmit hash | |
904 | policy. | |
905 | ||
00354cfb JV |
906 | This algorithm is not fully 802.3ad compliant. A |
907 | single TCP or UDP conversation containing both | |
908 | fragmented and unfragmented packets will see packets | |
909 | striped across two interfaces. This may result in out | |
910 | of order delivery. Most traffic types will not meet | |
911 | this criteria, as TCP rarely fragments traffic, and | |
912 | most UDP traffic is not involved in extended | |
913 | conversations. Other implementations of 802.3ad may | |
914 | or may not tolerate this noncompliance. | |
915 | ||
7a6afab1 NA |
916 | encap2+3 |
917 | ||
918 | This policy uses the same formula as layer2+3 but it | |
919 | relies on skb_flow_dissect to obtain the header fields | |
920 | which might result in the use of inner headers if an | |
921 | encapsulation protocol is used. For example this will | |
922 | improve the performance for tunnel users because the | |
923 | packets will be distributed according to the encapsulated | |
924 | flows. | |
925 | ||
926 | encap3+4 | |
927 | ||
928 | This policy uses the same formula as layer3+4 but it | |
929 | relies on skb_flow_dissect to obtain the header fields | |
930 | which might result in the use of inner headers if an | |
931 | encapsulation protocol is used. For example this will | |
932 | improve the performance for tunnel users because the | |
933 | packets will be distributed according to the encapsulated | |
934 | flows. | |
935 | ||
00354cfb | 936 | The default value is layer2. This option was added in bonding |
6f6652be JV |
937 | version 2.6.3. In earlier versions of bonding, this parameter |
938 | does not exist, and the layer2 policy is the only policy. The | |
939 | layer2+3 value was added for bonding version 3.2.2. | |
1da177e4 | 940 | |
c2952c31 FL |
941 | resend_igmp |
942 | ||
943 | Specifies the number of IGMP membership reports to be issued after | |
944 | a failover event. One membership report is issued immediately after | |
945 | the failover, subsequent packets are sent in each 200ms interval. | |
946 | ||
94265cf5 FL |
947 | The valid range is 0 - 255; the default value is 1. A value of 0 |
948 | prevents the IGMP membership report from being issued in response | |
949 | to the failover event. | |
950 | ||
951 | This option is useful for bonding modes balance-rr (0), active-backup | |
952 | (1), balance-tlb (5) and balance-alb (6), in which a failover can | |
953 | switch the IGMP traffic from one slave to another. Therefore a fresh | |
954 | IGMP report must be issued to cause the switch to forward the incoming | |
955 | IGMP traffic over the newly selected slave. | |
956 | ||
957 | This option was added for bonding version 3.7.0. | |
1da177e4 | 958 | |
84a6a0ac | 959 | lp_interval |
960 | ||
961 | Specifies the number of seconds between instances where the bonding | |
962 | driver sends learning packets to each slaves peer switch. | |
963 | ||
964 | The valid range is 1 - 0x7fffffff; the default value is 1. This Option | |
965 | has effect only in balance-tlb and balance-alb modes. | |
966 | ||
1da177e4 LT |
967 | 3. Configuring Bonding Devices |
968 | ============================== | |
969 | ||
6224e01d | 970 | You can configure bonding using either your distro's network |
b1098bbe | 971 | initialization scripts, or manually using either iproute2 or the |
de221bd5 NP |
972 | sysfs interface. Distros generally use one of three packages for the |
973 | network initialization scripts: initscripts, sysconfig or interfaces. | |
974 | Recent versions of these packages have support for bonding, while older | |
6224e01d | 975 | versions do not. |
1da177e4 LT |
976 | |
977 | We will first describe the options for configuring bonding for | |
de221bd5 NP |
978 | distros using versions of initscripts, sysconfig and interfaces with full |
979 | or partial support for bonding, then provide information on enabling | |
1da177e4 LT |
980 | bonding without support from the network initialization scripts (i.e., |
981 | older versions of initscripts or sysconfig). | |
982 | ||
de221bd5 NP |
983 | If you're unsure whether your distro uses sysconfig, |
984 | initscripts or interfaces, or don't know if it's new enough, have no fear. | |
1da177e4 LT |
985 | Determining this is fairly straightforward. |
986 | ||
de221bd5 NP |
987 | First, look for a file called interfaces in /etc/network directory. |
988 | If this file is present in your system, then your system use interfaces. See | |
989 | Configuration with Interfaces Support. | |
990 | ||
991 | Else, issue the command: | |
1da177e4 LT |
992 | |
993 | $ rpm -qf /sbin/ifup | |
994 | ||
995 | It will respond with a line of text starting with either | |
996 | "initscripts" or "sysconfig," followed by some numbers. This is the | |
997 | package that provides your network initialization scripts. | |
998 | ||
999 | Next, to determine if your installation supports bonding, | |
1000 | issue the command: | |
1001 | ||
1002 | $ grep ifenslave /sbin/ifup | |
1003 | ||
1004 | If this returns any matches, then your initscripts or | |
1005 | sysconfig has support for bonding. | |
1006 | ||
6224e01d | 1007 | 3.1 Configuration with Sysconfig Support |
1da177e4 LT |
1008 | ---------------------------------------- |
1009 | ||
1010 | This section applies to distros using a version of sysconfig | |
1011 | with bonding support, for example, SuSE Linux Enterprise Server 9. | |
1012 | ||
1013 | SuSE SLES 9's networking configuration system does support | |
1014 | bonding, however, at this writing, the YaST system configuration | |
6224e01d | 1015 | front end does not provide any means to work with bonding devices. |
1da177e4 LT |
1016 | Bonding devices can be managed by hand, however, as follows. |
1017 | ||
1018 | First, if they have not already been configured, configure the | |
1019 | slave devices. On SLES 9, this is most easily done by running the | |
1020 | yast2 sysconfig configuration utility. The goal is for to create an | |
1021 | ifcfg-id file for each slave device. The simplest way to accomplish | |
00354cfb JV |
1022 | this is to configure the devices for DHCP (this is only to get the |
1023 | file ifcfg-id file created; see below for some issues with DHCP). The | |
1024 | name of the configuration file for each device will be of the form: | |
1da177e4 LT |
1025 | |
1026 | ifcfg-id-xx:xx:xx:xx:xx:xx | |
1027 | ||
1028 | Where the "xx" portion will be replaced with the digits from | |
1029 | the device's permanent MAC address. | |
1030 | ||
1031 | Once the set of ifcfg-id-xx:xx:xx:xx:xx:xx files has been | |
1032 | created, it is necessary to edit the configuration files for the slave | |
1033 | devices (the MAC addresses correspond to those of the slave devices). | |
00354cfb | 1034 | Before editing, the file will contain multiple lines, and will look |
1da177e4 LT |
1035 | something like this: |
1036 | ||
1037 | BOOTPROTO='dhcp' | |
1038 | STARTMODE='on' | |
1039 | USERCTL='no' | |
1040 | UNIQUE='XNzu.WeZGOGF+4wE' | |
1041 | _nm_name='bus-pci-0001:61:01.0' | |
1042 | ||
1043 | Change the BOOTPROTO and STARTMODE lines to the following: | |
1044 | ||
1045 | BOOTPROTO='none' | |
1046 | STARTMODE='off' | |
1047 | ||
1048 | Do not alter the UNIQUE or _nm_name lines. Remove any other | |
1049 | lines (USERCTL, etc). | |
1050 | ||
1051 | Once the ifcfg-id-xx:xx:xx:xx:xx:xx files have been modified, | |
1052 | it's time to create the configuration file for the bonding device | |
1053 | itself. This file is named ifcfg-bondX, where X is the number of the | |
1054 | bonding device to create, starting at 0. The first such file is | |
1055 | ifcfg-bond0, the second is ifcfg-bond1, and so on. The sysconfig | |
1056 | network configuration system will correctly start multiple instances | |
1057 | of bonding. | |
1058 | ||
1059 | The contents of the ifcfg-bondX file is as follows: | |
1060 | ||
1061 | BOOTPROTO="static" | |
1062 | BROADCAST="10.0.2.255" | |
1063 | IPADDR="10.0.2.10" | |
1064 | NETMASK="255.255.0.0" | |
1065 | NETWORK="10.0.2.0" | |
1066 | REMOTE_IPADDR="" | |
1067 | STARTMODE="onboot" | |
1068 | BONDING_MASTER="yes" | |
1069 | BONDING_MODULE_OPTS="mode=active-backup miimon=100" | |
1070 | BONDING_SLAVE0="eth0" | |
00354cfb | 1071 | BONDING_SLAVE1="bus-pci-0000:06:08.1" |
1da177e4 LT |
1072 | |
1073 | Replace the sample BROADCAST, IPADDR, NETMASK and NETWORK | |
1074 | values with the appropriate values for your network. | |
1075 | ||
1da177e4 LT |
1076 | The STARTMODE specifies when the device is brought online. |
1077 | The possible values are: | |
1078 | ||
1079 | onboot: The device is started at boot time. If you're not | |
1080 | sure, this is probably what you want. | |
1081 | ||
1082 | manual: The device is started only when ifup is called | |
1083 | manually. Bonding devices may be configured this | |
1084 | way if you do not wish them to start automatically | |
1085 | at boot for some reason. | |
1086 | ||
1087 | hotplug: The device is started by a hotplug event. This is not | |
1088 | a valid choice for a bonding device. | |
1089 | ||
1090 | off or ignore: The device configuration is ignored. | |
1091 | ||
1092 | The line BONDING_MASTER='yes' indicates that the device is a | |
1093 | bonding master device. The only useful value is "yes." | |
1094 | ||
1095 | The contents of BONDING_MODULE_OPTS are supplied to the | |
1096 | instance of the bonding module for this device. Specify the options | |
1097 | for the bonding mode, link monitoring, and so on here. Do not include | |
1098 | the max_bonds bonding parameter; this will confuse the configuration | |
1099 | system if you have multiple bonding devices. | |
1100 | ||
00354cfb JV |
1101 | Finally, supply one BONDING_SLAVEn="slave device" for each |
1102 | slave. where "n" is an increasing value, one for each slave. The | |
1103 | "slave device" is either an interface name, e.g., "eth0", or a device | |
1104 | specifier for the network device. The interface name is easier to | |
1105 | find, but the ethN names are subject to change at boot time if, e.g., | |
1106 | a device early in the sequence has failed. The device specifiers | |
1107 | (bus-pci-0000:06:08.1 in the example above) specify the physical | |
1108 | network device, and will not change unless the device's bus location | |
1109 | changes (for example, it is moved from one PCI slot to another). The | |
1110 | example above uses one of each type for demonstration purposes; most | |
1111 | configurations will choose one or the other for all slave devices. | |
1da177e4 LT |
1112 | |
1113 | When all configuration files have been modified or created, | |
1114 | networking must be restarted for the configuration changes to take | |
1115 | effect. This can be accomplished via the following: | |
1116 | ||
1117 | # /etc/init.d/network restart | |
1118 | ||
1119 | Note that the network control script (/sbin/ifdown) will | |
1120 | remove the bonding module as part of the network shutdown processing, | |
1121 | so it is not necessary to remove the module by hand if, e.g., the | |
00354cfb | 1122 | module parameters have changed. |
1da177e4 LT |
1123 | |
1124 | Also, at this writing, YaST/YaST2 will not manage bonding | |
1125 | devices (they do not show bonding interfaces on its list of network | |
1126 | devices). It is necessary to edit the configuration file by hand to | |
1127 | change the bonding configuration. | |
1128 | ||
1129 | Additional general options and details of the ifcfg file | |
1130 | format can be found in an example ifcfg template file: | |
1131 | ||
1132 | /etc/sysconfig/network/ifcfg.template | |
1133 | ||
1134 | Note that the template does not document the various BONDING_ | |
1135 | settings described above, but does describe many of the other options. | |
1136 | ||
6224e01d | 1137 | 3.1.1 Using DHCP with Sysconfig |
00354cfb JV |
1138 | ------------------------------- |
1139 | ||
1140 | Under sysconfig, configuring a device with BOOTPROTO='dhcp' | |
1141 | will cause it to query DHCP for its IP address information. At this | |
1142 | writing, this does not function for bonding devices; the scripts | |
1143 | attempt to obtain the device address from DHCP prior to adding any of | |
1144 | the slave devices. Without active slaves, the DHCP requests are not | |
1145 | sent to the network. | |
1146 | ||
6224e01d | 1147 | 3.1.2 Configuring Multiple Bonds with Sysconfig |
00354cfb JV |
1148 | ----------------------------------------------- |
1149 | ||
1150 | The sysconfig network initialization system is capable of | |
1151 | handling multiple bonding devices. All that is necessary is for each | |
1152 | bonding instance to have an appropriately configured ifcfg-bondX file | |
1153 | (as described above). Do not specify the "max_bonds" parameter to any | |
1154 | instance of bonding, as this will confuse sysconfig. If you require | |
1155 | multiple bonding devices with identical parameters, create multiple | |
1156 | ifcfg-bondX files. | |
1157 | ||
1158 | Because the sysconfig scripts supply the bonding module | |
1159 | options in the ifcfg-bondX file, it is not necessary to add them to | |
970e2486 | 1160 | the system /etc/modules.d/*.conf configuration files. |
00354cfb | 1161 | |
6224e01d | 1162 | 3.2 Configuration with Initscripts Support |
1da177e4 LT |
1163 | ------------------------------------------ |
1164 | ||
9a6c6867 JV |
1165 | This section applies to distros using a recent version of |
1166 | initscripts with bonding support, for example, Red Hat Enterprise Linux | |
1167 | version 3 or later, Fedora, etc. On these systems, the network | |
1168 | initialization scripts have knowledge of bonding, and can be configured to | |
1169 | control bonding devices. Note that older versions of the initscripts | |
1170 | package have lower levels of support for bonding; this will be noted where | |
1171 | applicable. | |
1da177e4 LT |
1172 | |
1173 | These distros will not automatically load the network adapter | |
1174 | driver unless the ethX device is configured with an IP address. | |
1175 | Because of this constraint, users must manually configure a | |
1176 | network-script file for all physical adapters that will be members of | |
1177 | a bondX link. Network script files are located in the directory: | |
1178 | ||
1179 | /etc/sysconfig/network-scripts | |
1180 | ||
1181 | The file name must be prefixed with "ifcfg-eth" and suffixed | |
1182 | with the adapter's physical adapter number. For example, the script | |
1183 | for eth0 would be named /etc/sysconfig/network-scripts/ifcfg-eth0. | |
1184 | Place the following text in the file: | |
1185 | ||
1186 | DEVICE=eth0 | |
1187 | USERCTL=no | |
1188 | ONBOOT=yes | |
1189 | MASTER=bond0 | |
1190 | SLAVE=yes | |
1191 | BOOTPROTO=none | |
1192 | ||
1193 | The DEVICE= line will be different for every ethX device and | |
1194 | must correspond with the name of the file, i.e., ifcfg-eth1 must have | |
1195 | a device line of DEVICE=eth1. The setting of the MASTER= line will | |
1196 | also depend on the final bonding interface name chosen for your bond. | |
1197 | As with other network devices, these typically start at 0, and go up | |
1198 | one for each device, i.e., the first bonding instance is bond0, the | |
1199 | second is bond1, and so on. | |
1200 | ||
1201 | Next, create a bond network script. The file name for this | |
1202 | script will be /etc/sysconfig/network-scripts/ifcfg-bondX where X is | |
1203 | the number of the bond. For bond0 the file is named "ifcfg-bond0", | |
1204 | for bond1 it is named "ifcfg-bond1", and so on. Within that file, | |
1205 | place the following text: | |
1206 | ||
1207 | DEVICE=bond0 | |
1208 | IPADDR=192.168.1.1 | |
1209 | NETMASK=255.255.255.0 | |
1210 | NETWORK=192.168.1.0 | |
1211 | BROADCAST=192.168.1.255 | |
1212 | ONBOOT=yes | |
1213 | BOOTPROTO=none | |
1214 | USERCTL=no | |
1215 | ||
1216 | Be sure to change the networking specific lines (IPADDR, | |
1217 | NETMASK, NETWORK and BROADCAST) to match your network configuration. | |
1218 | ||
9a6c6867 | 1219 | For later versions of initscripts, such as that found with Fedora |
3f8b4b13 AG |
1220 | 7 (or later) and Red Hat Enterprise Linux version 5 (or later), it is possible, |
1221 | and, indeed, preferable, to specify the bonding options in the ifcfg-bond0 | |
9a6c6867 JV |
1222 | file, e.g. a line of the format: |
1223 | ||
3f8b4b13 | 1224 | BONDING_OPTS="mode=active-backup arp_interval=60 arp_ip_target=192.168.1.254" |
9a6c6867 JV |
1225 | |
1226 | will configure the bond with the specified options. The options | |
1227 | specified in BONDING_OPTS are identical to the bonding module parameters | |
3f8b4b13 AG |
1228 | except for the arp_ip_target field when using versions of initscripts older |
1229 | than and 8.57 (Fedora 8) and 8.45.19 (Red Hat Enterprise Linux 5.2). When | |
1230 | using older versions each target should be included as a separate option and | |
1231 | should be preceded by a '+' to indicate it should be added to the list of | |
1232 | queried targets, e.g., | |
9a6c6867 JV |
1233 | |
1234 | arp_ip_target=+192.168.1.1 arp_ip_target=+192.168.1.2 | |
1235 | ||
1236 | is the proper syntax to specify multiple targets. When specifying | |
970e2486 | 1237 | options via BONDING_OPTS, it is not necessary to edit /etc/modprobe.d/*.conf. |
9a6c6867 | 1238 | |
3f8b4b13 | 1239 | For even older versions of initscripts that do not support |
970e2486 LDM |
1240 | BONDING_OPTS, it is necessary to edit /etc/modprobe.d/*.conf, depending upon |
1241 | your distro) to load the bonding module with your desired options when the | |
1242 | bond0 interface is brought up. The following lines in /etc/modprobe.d/*.conf | |
1243 | will load the bonding module, and select its options: | |
1da177e4 LT |
1244 | |
1245 | alias bond0 bonding | |
1246 | options bond0 mode=balance-alb miimon=100 | |
1247 | ||
1248 | Replace the sample parameters with the appropriate set of | |
1249 | options for your configuration. | |
1250 | ||
1251 | Finally run "/etc/rc.d/init.d/network restart" as root. This | |
1252 | will restart the networking subsystem and your bond link should be now | |
1253 | up and running. | |
1254 | ||
6224e01d | 1255 | 3.2.1 Using DHCP with Initscripts |
00354cfb JV |
1256 | --------------------------------- |
1257 | ||
9a6c6867 JV |
1258 | Recent versions of initscripts (the versions supplied with Fedora |
1259 | Core 3 and Red Hat Enterprise Linux 4, or later versions, are reported to | |
1260 | work) have support for assigning IP information to bonding devices via | |
1261 | DHCP. | |
00354cfb JV |
1262 | |
1263 | To configure bonding for DHCP, configure it as described | |
1264 | above, except replace the line "BOOTPROTO=none" with "BOOTPROTO=dhcp" | |
1265 | and add a line consisting of "TYPE=Bonding". Note that the TYPE value | |
1266 | is case sensitive. | |
1267 | ||
6224e01d | 1268 | 3.2.2 Configuring Multiple Bonds with Initscripts |
00354cfb JV |
1269 | ------------------------------------------------- |
1270 | ||
9a6c6867 JV |
1271 | Initscripts packages that are included with Fedora 7 and Red Hat |
1272 | Enterprise Linux 5 support multiple bonding interfaces by simply | |
1273 | specifying the appropriate BONDING_OPTS= in ifcfg-bondX where X is the | |
1274 | number of the bond. This support requires sysfs support in the kernel, | |
1275 | and a bonding driver of version 3.0.0 or later. Other configurations may | |
1276 | not support this method for specifying multiple bonding interfaces; for | |
1277 | those instances, see the "Configuring Multiple Bonds Manually" section, | |
1278 | below. | |
1da177e4 | 1279 | |
b1098bbe | 1280 | 3.3 Configuring Bonding Manually with iproute2 |
6224e01d | 1281 | ----------------------------------------------- |
1da177e4 LT |
1282 | |
1283 | This section applies to distros whose network initialization | |
1284 | scripts (the sysconfig or initscripts package) do not have specific | |
1285 | knowledge of bonding. One such distro is SuSE Linux Enterprise Server | |
1286 | version 8. | |
1287 | ||
00354cfb | 1288 | The general method for these systems is to place the bonding |
970e2486 | 1289 | module parameters into a config file in /etc/modprobe.d/ (as |
00354cfb | 1290 | appropriate for the installed distro), then add modprobe and/or |
b1098bbe | 1291 | `ip link` commands to the system's global init script. The name of |
00354cfb | 1292 | the global init script differs; for sysconfig, it is |
1da177e4 LT |
1293 | /etc/init.d/boot.local and for initscripts it is /etc/rc.d/rc.local. |
1294 | ||
1295 | For example, if you wanted to make a simple bond of two e100 | |
1296 | devices (presumed to be eth0 and eth1), and have it persist across | |
1297 | reboots, edit the appropriate file (/etc/init.d/boot.local or | |
1298 | /etc/rc.d/rc.local), and add the following: | |
1299 | ||
00354cfb | 1300 | modprobe bonding mode=balance-alb miimon=100 |
1da177e4 LT |
1301 | modprobe e100 |
1302 | ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up | |
b1098bbe CW |
1303 | ip link set eth0 master bond0 |
1304 | ip link set eth1 master bond0 | |
1da177e4 LT |
1305 | |
1306 | Replace the example bonding module parameters and bond0 | |
1307 | network configuration (IP address, netmask, etc) with the appropriate | |
00354cfb | 1308 | values for your configuration. |
1da177e4 LT |
1309 | |
1310 | Unfortunately, this method will not provide support for the | |
1311 | ifup and ifdown scripts on the bond devices. To reload the bonding | |
1312 | configuration, it is necessary to run the initialization script, e.g., | |
1313 | ||
1314 | # /etc/init.d/boot.local | |
1315 | ||
1316 | or | |
1317 | ||
1318 | # /etc/rc.d/rc.local | |
1319 | ||
1320 | It may be desirable in such a case to create a separate script | |
1321 | which only initializes the bonding configuration, then call that | |
1322 | separate script from within boot.local. This allows for bonding to be | |
1323 | enabled without re-running the entire global init script. | |
1324 | ||
1325 | To shut down the bonding devices, it is necessary to first | |
1326 | mark the bonding device itself as being down, then remove the | |
1327 | appropriate device driver modules. For our example above, you can do | |
1328 | the following: | |
1329 | ||
1330 | # ifconfig bond0 down | |
00354cfb | 1331 | # rmmod bonding |
1da177e4 LT |
1332 | # rmmod e100 |
1333 | ||
1334 | Again, for convenience, it may be desirable to create a script | |
1335 | with these commands. | |
1336 | ||
1337 | ||
00354cfb JV |
1338 | 3.3.1 Configuring Multiple Bonds Manually |
1339 | ----------------------------------------- | |
1da177e4 LT |
1340 | |
1341 | This section contains information on configuring multiple | |
00354cfb JV |
1342 | bonding devices with differing options for those systems whose network |
1343 | initialization scripts lack support for configuring multiple bonds. | |
1344 | ||
1345 | If you require multiple bonding devices, but all with the same | |
1346 | options, you may wish to use the "max_bonds" module parameter, | |
1347 | documented above. | |
1da177e4 | 1348 | |
9a6c6867 | 1349 | To create multiple bonding devices with differing options, it is |
f8b72d36 | 1350 | preferable to use bonding parameters exported by sysfs, documented in the |
9a6c6867 JV |
1351 | section below. |
1352 | ||
1353 | For versions of bonding without sysfs support, the only means to | |
1354 | provide multiple instances of bonding with differing options is to load | |
1355 | the bonding driver multiple times. Note that current versions of the | |
1356 | sysconfig network initialization scripts handle this automatically; if | |
1357 | your distro uses these scripts, no special action is needed. See the | |
1358 | section Configuring Bonding Devices, above, if you're not sure about your | |
1359 | network initialization scripts. | |
1360 | ||
1361 | To load multiple instances of the module, it is necessary to | |
1362 | specify a different name for each instance (the module loading system | |
1363 | requires that every loaded module, even multiple instances of the same | |
1364 | module, have a unique name). This is accomplished by supplying multiple | |
970e2486 | 1365 | sets of bonding options in /etc/modprobe.d/*.conf, for example: |
9a6c6867 JV |
1366 | |
1367 | alias bond0 bonding | |
1368 | options bond0 -o bond0 mode=balance-rr miimon=100 | |
1369 | ||
1370 | alias bond1 bonding | |
1371 | options bond1 -o bond1 mode=balance-alb miimon=50 | |
1372 | ||
1373 | will load the bonding module two times. The first instance is | |
1374 | named "bond0" and creates the bond0 device in balance-rr mode with an | |
1375 | miimon of 100. The second instance is named "bond1" and creates the | |
1376 | bond1 device in balance-alb mode with an miimon of 50. | |
1377 | ||
1378 | In some circumstances (typically with older distributions), | |
1379 | the above does not work, and the second bonding instance never sees | |
1380 | its options. In that case, the second options line can be substituted | |
1381 | as follows: | |
1382 | ||
1383 | install bond1 /sbin/modprobe --ignore-install bonding -o bond1 \ | |
1384 | mode=balance-alb miimon=50 | |
00354cfb | 1385 | |
9a6c6867 JV |
1386 | This may be repeated any number of times, specifying a new and |
1387 | unique name in place of bond1 for each subsequent instance. | |
1388 | ||
1389 | It has been observed that some Red Hat supplied kernels are unable | |
1390 | to rename modules at load time (the "-o bond1" part). Attempts to pass | |
1391 | that option to modprobe will produce an "Operation not permitted" error. | |
1392 | This has been reported on some Fedora Core kernels, and has been seen on | |
1393 | RHEL 4 as well. On kernels exhibiting this problem, it will be impossible | |
1394 | to configure multiple bonds with differing parameters (as they are older | |
1395 | kernels, and also lack sysfs support). | |
1da177e4 | 1396 | |
6224e01d AK |
1397 | 3.4 Configuring Bonding Manually via Sysfs |
1398 | ------------------------------------------ | |
1399 | ||
9a6c6867 | 1400 | Starting with version 3.0.0, Channel Bonding may be configured |
6224e01d AK |
1401 | via the sysfs interface. This interface allows dynamic configuration |
1402 | of all bonds in the system without unloading the module. It also | |
1403 | allows for adding and removing bonds at runtime. Ifenslave is no | |
1404 | longer required, though it is still supported. | |
1405 | ||
1406 | Use of the sysfs interface allows you to use multiple bonds | |
1407 | with different configurations without having to reload the module. | |
1408 | It also allows you to use multiple, differently configured bonds when | |
1409 | bonding is compiled into the kernel. | |
1410 | ||
1411 | You must have the sysfs filesystem mounted to configure | |
1412 | bonding this way. The examples in this document assume that you | |
1413 | are using the standard mount point for sysfs, e.g. /sys. If your | |
1414 | sysfs filesystem is mounted elsewhere, you will need to adjust the | |
1415 | example paths accordingly. | |
1416 | ||
1417 | Creating and Destroying Bonds | |
1418 | ----------------------------- | |
1419 | To add a new bond foo: | |
1420 | # echo +foo > /sys/class/net/bonding_masters | |
1421 | ||
1422 | To remove an existing bond bar: | |
1423 | # echo -bar > /sys/class/net/bonding_masters | |
1424 | ||
1425 | To show all existing bonds: | |
1426 | # cat /sys/class/net/bonding_masters | |
1427 | ||
1428 | NOTE: due to 4K size limitation of sysfs files, this list may be | |
1429 | truncated if you have more than a few hundred bonds. This is unlikely | |
1430 | to occur under normal operating conditions. | |
1431 | ||
1432 | Adding and Removing Slaves | |
1433 | -------------------------- | |
1434 | Interfaces may be enslaved to a bond using the file | |
1435 | /sys/class/net/<bond>/bonding/slaves. The semantics for this file | |
1436 | are the same as for the bonding_masters file. | |
1437 | ||
1438 | To enslave interface eth0 to bond bond0: | |
1439 | # ifconfig bond0 up | |
1440 | # echo +eth0 > /sys/class/net/bond0/bonding/slaves | |
1441 | ||
1442 | To free slave eth0 from bond bond0: | |
1443 | # echo -eth0 > /sys/class/net/bond0/bonding/slaves | |
1444 | ||
6224e01d AK |
1445 | When an interface is enslaved to a bond, symlinks between the |
1446 | two are created in the sysfs filesystem. In this case, you would get | |
1447 | /sys/class/net/bond0/slave_eth0 pointing to /sys/class/net/eth0, and | |
1448 | /sys/class/net/eth0/master pointing to /sys/class/net/bond0. | |
1449 | ||
1450 | This means that you can tell quickly whether or not an | |
1451 | interface is enslaved by looking for the master symlink. Thus: | |
1452 | # echo -eth0 > /sys/class/net/eth0/master/bonding/slaves | |
1453 | will free eth0 from whatever bond it is enslaved to, regardless of | |
1454 | the name of the bond interface. | |
1455 | ||
1456 | Changing a Bond's Configuration | |
1457 | ------------------------------- | |
1458 | Each bond may be configured individually by manipulating the | |
1459 | files located in /sys/class/net/<bond name>/bonding | |
1460 | ||
1461 | The names of these files correspond directly with the command- | |
670e9f34 | 1462 | line parameters described elsewhere in this file, and, with the |
6224e01d AK |
1463 | exception of arp_ip_target, they accept the same values. To see the |
1464 | current setting, simply cat the appropriate file. | |
1465 | ||
1466 | A few examples will be given here; for specific usage | |
1467 | guidelines for each parameter, see the appropriate section in this | |
1468 | document. | |
1469 | ||
1470 | To configure bond0 for balance-alb mode: | |
1471 | # ifconfig bond0 down | |
1472 | # echo 6 > /sys/class/net/bond0/bonding/mode | |
1473 | - or - | |
1474 | # echo balance-alb > /sys/class/net/bond0/bonding/mode | |
1475 | NOTE: The bond interface must be down before the mode can be | |
1476 | changed. | |
1477 | ||
1478 | To enable MII monitoring on bond0 with a 1 second interval: | |
1479 | # echo 1000 > /sys/class/net/bond0/bonding/miimon | |
1480 | NOTE: If ARP monitoring is enabled, it will disabled when MII | |
1481 | monitoring is enabled, and vice-versa. | |
1482 | ||
1483 | To add ARP targets: | |
1484 | # echo +192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target | |
1485 | # echo +192.168.0.101 > /sys/class/net/bond0/bonding/arp_ip_target | |
5a31bec0 | 1486 | NOTE: up to 16 target addresses may be specified. |
6224e01d AK |
1487 | |
1488 | To remove an ARP target: | |
1489 | # echo -192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target | |
1490 | ||
7eacd038 NH |
1491 | To configure the interval between learning packet transmits: |
1492 | # echo 12 > /sys/class/net/bond0/bonding/lp_interval | |
1493 | NOTE: the lp_inteval is the number of seconds between instances where | |
1494 | the bonding driver sends learning packets to each slaves peer switch. The | |
1495 | default interval is 1 second. | |
1496 | ||
6224e01d AK |
1497 | Example Configuration |
1498 | --------------------- | |
1499 | We begin with the same example that is shown in section 3.3, | |
1500 | executed with sysfs, and without using ifenslave. | |
1501 | ||
1502 | To make a simple bond of two e100 devices (presumed to be eth0 | |
1503 | and eth1), and have it persist across reboots, edit the appropriate | |
1504 | file (/etc/init.d/boot.local or /etc/rc.d/rc.local), and add the | |
1505 | following: | |
1506 | ||
1507 | modprobe bonding | |
1508 | modprobe e100 | |
1509 | echo balance-alb > /sys/class/net/bond0/bonding/mode | |
1510 | ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up | |
1511 | echo 100 > /sys/class/net/bond0/bonding/miimon | |
1512 | echo +eth0 > /sys/class/net/bond0/bonding/slaves | |
1513 | echo +eth1 > /sys/class/net/bond0/bonding/slaves | |
1514 | ||
1515 | To add a second bond, with two e1000 interfaces in | |
1516 | active-backup mode, using ARP monitoring, add the following lines to | |
1517 | your init script: | |
1518 | ||
1519 | modprobe e1000 | |
1520 | echo +bond1 > /sys/class/net/bonding_masters | |
1521 | echo active-backup > /sys/class/net/bond1/bonding/mode | |
1522 | ifconfig bond1 192.168.2.1 netmask 255.255.255.0 up | |
1523 | echo +192.168.2.100 /sys/class/net/bond1/bonding/arp_ip_target | |
1524 | echo 2000 > /sys/class/net/bond1/bonding/arp_interval | |
1525 | echo +eth2 > /sys/class/net/bond1/bonding/slaves | |
1526 | echo +eth3 > /sys/class/net/bond1/bonding/slaves | |
1527 | ||
de221bd5 NP |
1528 | 3.5 Configuration with Interfaces Support |
1529 | ----------------------------------------- | |
1530 | ||
1531 | This section applies to distros which use /etc/network/interfaces file | |
1532 | to describe network interface configuration, most notably Debian and it's | |
1533 | derivatives. | |
1534 | ||
1535 | The ifup and ifdown commands on Debian don't support bonding out of | |
1536 | the box. The ifenslave-2.6 package should be installed to provide bonding | |
1537 | support. Once installed, this package will provide bond-* options to be used | |
1538 | into /etc/network/interfaces. | |
1539 | ||
1540 | Note that ifenslave-2.6 package will load the bonding module and use | |
1541 | the ifenslave command when appropriate. | |
1542 | ||
1543 | Example Configurations | |
1544 | ---------------------- | |
1545 | ||
1546 | In /etc/network/interfaces, the following stanza will configure bond0, in | |
1547 | active-backup mode, with eth0 and eth1 as slaves. | |
1548 | ||
1549 | auto bond0 | |
1550 | iface bond0 inet dhcp | |
1551 | bond-slaves eth0 eth1 | |
1552 | bond-mode active-backup | |
1553 | bond-miimon 100 | |
1554 | bond-primary eth0 eth1 | |
1555 | ||
1556 | If the above configuration doesn't work, you might have a system using | |
1557 | upstart for system startup. This is most notably true for recent | |
1558 | Ubuntu versions. The following stanza in /etc/network/interfaces will | |
1559 | produce the same result on those systems. | |
1560 | ||
1561 | auto bond0 | |
1562 | iface bond0 inet dhcp | |
1563 | bond-slaves none | |
1564 | bond-mode active-backup | |
1565 | bond-miimon 100 | |
1566 | ||
1567 | auto eth0 | |
1568 | iface eth0 inet manual | |
1569 | bond-master bond0 | |
1570 | bond-primary eth0 eth1 | |
1571 | ||
1572 | auto eth1 | |
1573 | iface eth1 inet manual | |
1574 | bond-master bond0 | |
1575 | bond-primary eth0 eth1 | |
1576 | ||
1577 | For a full list of bond-* supported options in /etc/network/interfaces and some | |
1578 | more advanced examples tailored to you particular distros, see the files in | |
1579 | /usr/share/doc/ifenslave-2.6. | |
1580 | ||
1581 | 3.6 Overriding Configuration for Special Cases | |
bb1d9123 | 1582 | ---------------------------------------------- |
de221bd5 | 1583 | |
bb1d9123 AG |
1584 | When using the bonding driver, the physical port which transmits a frame is |
1585 | typically selected by the bonding driver, and is not relevant to the user or | |
1586 | system administrator. The output port is simply selected using the policies of | |
1587 | the selected bonding mode. On occasion however, it is helpful to direct certain | |
1588 | classes of traffic to certain physical interfaces on output to implement | |
1589 | slightly more complex policies. For example, to reach a web server over a | |
1590 | bonded interface in which eth0 connects to a private network, while eth1 | |
1591 | connects via a public network, it may be desirous to bias the bond to send said | |
1592 | traffic over eth0 first, using eth1 only as a fall back, while all other traffic | |
1593 | can safely be sent over either interface. Such configurations may be achieved | |
1594 | using the traffic control utilities inherent in linux. | |
1595 | ||
1596 | By default the bonding driver is multiqueue aware and 16 queues are created | |
1597 | when the driver initializes (see Documentation/networking/multiqueue.txt | |
1598 | for details). If more or less queues are desired the module parameter | |
1599 | tx_queues can be used to change this value. There is no sysfs parameter | |
1600 | available as the allocation is done at module init time. | |
1601 | ||
1602 | The output of the file /proc/net/bonding/bondX has changed so the output Queue | |
1603 | ID is now printed for each slave: | |
1604 | ||
1605 | Bonding Mode: fault-tolerance (active-backup) | |
1606 | Primary Slave: None | |
1607 | Currently Active Slave: eth0 | |
1608 | MII Status: up | |
1609 | MII Polling Interval (ms): 0 | |
1610 | Up Delay (ms): 0 | |
1611 | Down Delay (ms): 0 | |
1612 | ||
1613 | Slave Interface: eth0 | |
1614 | MII Status: up | |
1615 | Link Failure Count: 0 | |
1616 | Permanent HW addr: 00:1a:a0:12:8f:cb | |
1617 | Slave queue ID: 0 | |
1618 | ||
1619 | Slave Interface: eth1 | |
1620 | MII Status: up | |
1621 | Link Failure Count: 0 | |
1622 | Permanent HW addr: 00:1a:a0:12:8f:cc | |
1623 | Slave queue ID: 2 | |
1624 | ||
1625 | The queue_id for a slave can be set using the command: | |
1626 | ||
1627 | # echo "eth1:2" > /sys/class/net/bond0/bonding/queue_id | |
1628 | ||
1629 | Any interface that needs a queue_id set should set it with multiple calls | |
1630 | like the one above until proper priorities are set for all interfaces. On | |
1631 | distributions that allow configuration via initscripts, multiple 'queue_id' | |
1632 | arguments can be added to BONDING_OPTS to set all needed slave queues. | |
1633 | ||
1634 | These queue id's can be used in conjunction with the tc utility to configure | |
1635 | a multiqueue qdisc and filters to bias certain traffic to transmit on certain | |
1636 | slave devices. For instance, say we wanted, in the above configuration to | |
1637 | force all traffic bound to 192.168.1.100 to use eth1 in the bond as its output | |
1638 | device. The following commands would accomplish this: | |
1639 | ||
1640 | # tc qdisc add dev bond0 handle 1 root multiq | |
1641 | ||
1642 | # tc filter add dev bond0 protocol ip parent 1: prio 1 u32 match ip dst \ | |
1643 | 192.168.1.100 action skbedit queue_mapping 2 | |
1644 | ||
1645 | These commands tell the kernel to attach a multiqueue queue discipline to the | |
1646 | bond0 interface and filter traffic enqueued to it, such that packets with a dst | |
1647 | ip of 192.168.1.100 have their output queue mapping value overwritten to 2. | |
1648 | This value is then passed into the driver, causing the normal output path | |
1649 | selection policy to be overridden, selecting instead qid 2, which maps to eth1. | |
1650 | ||
1651 | Note that qid values begin at 1. Qid 0 is reserved to initiate to the driver | |
1652 | that normal output policy selection should take place. One benefit to simply | |
1653 | leaving the qid for a slave to 0 is the multiqueue awareness in the bonding | |
1654 | driver that is now present. This awareness allows tc filters to be placed on | |
1655 | slave devices as well as bond devices and the bonding driver will simply act as | |
1656 | a pass-through for selecting output queues on the slave device rather than | |
1657 | output port selection. | |
1658 | ||
1659 | This feature first appeared in bonding driver version 3.7.0 and support for | |
1660 | output slave selection was limited to round-robin and active-backup modes. | |
1661 | ||
d22a5fc0 MB |
1662 | 3.7 Configuring LACP for 802.3ad mode in a more secure way |
1663 | ---------------------------------------------------------- | |
1664 | ||
1665 | When using 802.3ad bonding mode, the Actor (host) and Partner (switch) | |
1666 | exchange LACPDUs. These LACPDUs cannot be sniffed, because they are | |
1667 | destined to link local mac addresses (which switches/bridges are not | |
1668 | supposed to forward). However, most of the values are easily predictable | |
1669 | or are simply the machine's MAC address (which is trivially known to all | |
1670 | other hosts in the same L2). This implies that other machines in the L2 | |
1671 | domain can spoof LACPDU packets from other hosts to the switch and potentially | |
1672 | cause mayhem by joining (from the point of view of the switch) another | |
1673 | machine's aggregate, thus receiving a portion of that hosts incoming | |
1674 | traffic and / or spoofing traffic from that machine themselves (potentially | |
1675 | even successfully terminating some portion of flows). Though this is not | |
1676 | a likely scenario, one could avoid this possibility by simply configuring | |
1677 | few bonding parameters: | |
1678 | ||
1679 | (a) ad_actor_system : You can set a random mac-address that can be used for | |
1680 | these LACPDU exchanges. The value can not be either NULL or Multicast. | |
1681 | Also it's preferable to set the local-admin bit. Following shell code | |
1682 | generates a random mac-address as described above. | |
1683 | ||
1684 | # sys_mac_addr=$(printf '%02x:%02x:%02x:%02x:%02x:%02x' \ | |
1685 | $(( (RANDOM & 0xFE) | 0x02 )) \ | |
1686 | $(( RANDOM & 0xFF )) \ | |
1687 | $(( RANDOM & 0xFF )) \ | |
1688 | $(( RANDOM & 0xFF )) \ | |
1689 | $(( RANDOM & 0xFF )) \ | |
1690 | $(( RANDOM & 0xFF ))) | |
1691 | # echo $sys_mac_addr > /sys/class/net/bond0/bonding/ad_actor_system | |
1692 | ||
1693 | (b) ad_actor_sys_prio : Randomize the system priority. The default value | |
1694 | is 65535, but system can take the value from 1 - 65535. Following shell | |
1695 | code generates random priority and sets it. | |
1696 | ||
1697 | # sys_prio=$(( 1 + RANDOM + RANDOM )) | |
1698 | # echo $sys_prio > /sys/class/net/bond0/bonding/ad_actor_sys_prio | |
1699 | ||
1700 | (c) ad_user_port_key : Use the user portion of the port-key. The default | |
1701 | keeps this empty. These are the upper 10 bits of the port-key and value | |
1702 | ranges from 0 - 1023. Following shell code generates these 10 bits and | |
1703 | sets it. | |
1704 | ||
1705 | # usr_port_key=$(( RANDOM & 0x3FF )) | |
1706 | # echo $usr_port_key > /sys/class/net/bond0/bonding/ad_user_port_key | |
1707 | ||
1708 | ||
bb1d9123 | 1709 | 4 Querying Bonding Configuration |
1da177e4 LT |
1710 | ================================= |
1711 | ||
6224e01d | 1712 | 4.1 Bonding Configuration |
1da177e4 LT |
1713 | ------------------------- |
1714 | ||
1715 | Each bonding device has a read-only file residing in the | |
1716 | /proc/net/bonding directory. The file contents include information | |
1717 | about the bonding configuration, options and state of each slave. | |
1718 | ||
1719 | For example, the contents of /proc/net/bonding/bond0 after the | |
1720 | driver is loaded with parameters of mode=0 and miimon=1000 is | |
1721 | generally as follows: | |
1722 | ||
1723 | Ethernet Channel Bonding Driver: 2.6.1 (October 29, 2004) | |
1724 | Bonding Mode: load balancing (round-robin) | |
1725 | Currently Active Slave: eth0 | |
1726 | MII Status: up | |
1727 | MII Polling Interval (ms): 1000 | |
1728 | Up Delay (ms): 0 | |
1729 | Down Delay (ms): 0 | |
1730 | ||
1731 | Slave Interface: eth1 | |
1732 | MII Status: up | |
1733 | Link Failure Count: 1 | |
1734 | ||
1735 | Slave Interface: eth0 | |
1736 | MII Status: up | |
1737 | Link Failure Count: 1 | |
1738 | ||
1739 | The precise format and contents will change depending upon the | |
1740 | bonding configuration, state, and version of the bonding driver. | |
1741 | ||
6224e01d | 1742 | 4.2 Network configuration |
1da177e4 LT |
1743 | ------------------------- |
1744 | ||
1745 | The network configuration can be inspected using the ifconfig | |
1746 | command. Bonding devices will have the MASTER flag set; Bonding slave | |
1747 | devices will have the SLAVE flag set. The ifconfig output does not | |
1748 | contain information on which slaves are associated with which masters. | |
1749 | ||
1750 | In the example below, the bond0 interface is the master | |
1751 | (MASTER) while eth0 and eth1 are slaves (SLAVE). Notice all slaves of | |
1752 | bond0 have the same MAC address (HWaddr) as bond0 for all modes except | |
1753 | TLB and ALB that require a unique MAC address for each slave. | |
1754 | ||
1755 | # /sbin/ifconfig | |
1756 | bond0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 | |
1757 | inet addr:XXX.XXX.XXX.YYY Bcast:XXX.XXX.XXX.255 Mask:255.255.252.0 | |
1758 | UP BROADCAST RUNNING MASTER MULTICAST MTU:1500 Metric:1 | |
1759 | RX packets:7224794 errors:0 dropped:0 overruns:0 frame:0 | |
1760 | TX packets:3286647 errors:1 dropped:0 overruns:1 carrier:0 | |
1761 | collisions:0 txqueuelen:0 | |
1762 | ||
1763 | eth0 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 | |
1da177e4 LT |
1764 | UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1 |
1765 | RX packets:3573025 errors:0 dropped:0 overruns:0 frame:0 | |
1766 | TX packets:1643167 errors:1 dropped:0 overruns:1 carrier:0 | |
1767 | collisions:0 txqueuelen:100 | |
1768 | Interrupt:10 Base address:0x1080 | |
1769 | ||
1770 | eth1 Link encap:Ethernet HWaddr 00:C0:F0:1F:37:B4 | |
1da177e4 LT |
1771 | UP BROADCAST RUNNING SLAVE MULTICAST MTU:1500 Metric:1 |
1772 | RX packets:3651769 errors:0 dropped:0 overruns:0 frame:0 | |
1773 | TX packets:1643480 errors:0 dropped:0 overruns:0 carrier:0 | |
1774 | collisions:0 txqueuelen:100 | |
1775 | Interrupt:9 Base address:0x1400 | |
1776 | ||
6224e01d | 1777 | 5. Switch Configuration |
1da177e4 LT |
1778 | ======================= |
1779 | ||
1780 | For this section, "switch" refers to whatever system the | |
1781 | bonded devices are directly connected to (i.e., where the other end of | |
1782 | the cable plugs into). This may be an actual dedicated switch device, | |
1783 | or it may be another regular system (e.g., another computer running | |
1784 | Linux), | |
1785 | ||
1786 | The active-backup, balance-tlb and balance-alb modes do not | |
1787 | require any specific configuration of the switch. | |
1788 | ||
1789 | The 802.3ad mode requires that the switch have the appropriate | |
1790 | ports configured as an 802.3ad aggregation. The precise method used | |
1791 | to configure this varies from switch to switch, but, for example, a | |
1792 | Cisco 3550 series switch requires that the appropriate ports first be | |
1793 | grouped together in a single etherchannel instance, then that | |
1794 | etherchannel is set to mode "lacp" to enable 802.3ad (instead of | |
1795 | standard EtherChannel). | |
1796 | ||
1797 | The balance-rr, balance-xor and broadcast modes generally | |
1798 | require that the switch have the appropriate ports grouped together. | |
1799 | The nomenclature for such a group differs between switches, it may be | |
1800 | called an "etherchannel" (as in the Cisco example, above), a "trunk | |
1801 | group" or some other similar variation. For these modes, each switch | |
1802 | will also have its own configuration options for the switch's transmit | |
1803 | policy to the bond. Typical choices include XOR of either the MAC or | |
1804 | IP addresses. The transmit policy of the two peers does not need to | |
1805 | match. For these three modes, the bonding mode really selects a | |
1806 | transmit policy for an EtherChannel group; all three will interoperate | |
1807 | with another EtherChannel group. | |
1808 | ||
1809 | ||
6224e01d | 1810 | 6. 802.1q VLAN Support |
1da177e4 LT |
1811 | ====================== |
1812 | ||
1813 | It is possible to configure VLAN devices over a bond interface | |
1814 | using the 8021q driver. However, only packets coming from the 8021q | |
1815 | driver and passing through bonding will be tagged by default. Self | |
1816 | generated packets, for example, bonding's learning packets or ARP | |
1817 | packets generated by either ALB mode or the ARP monitor mechanism, are | |
1818 | tagged internally by bonding itself. As a result, bonding must | |
1819 | "learn" the VLAN IDs configured above it, and use those IDs to tag | |
1820 | self generated packets. | |
1821 | ||
1822 | For reasons of simplicity, and to support the use of adapters | |
00354cfb JV |
1823 | that can do VLAN hardware acceleration offloading, the bonding |
1824 | interface declares itself as fully hardware offloading capable, it gets | |
1da177e4 LT |
1825 | the add_vid/kill_vid notifications to gather the necessary |
1826 | information, and it propagates those actions to the slaves. In case | |
1827 | of mixed adapter types, hardware accelerated tagged packets that | |
1828 | should go through an adapter that is not offloading capable are | |
1829 | "un-accelerated" by the bonding driver so the VLAN tag sits in the | |
1830 | regular location. | |
1831 | ||
1832 | VLAN interfaces *must* be added on top of a bonding interface | |
1833 | only after enslaving at least one slave. The bonding interface has a | |
1834 | hardware address of 00:00:00:00:00:00 until the first slave is added. | |
1835 | If the VLAN interface is created prior to the first enslavement, it | |
1836 | would pick up the all-zeroes hardware address. Once the first slave | |
1837 | is attached to the bond, the bond device itself will pick up the | |
1838 | slave's hardware address, which is then available for the VLAN device. | |
1839 | ||
1840 | Also, be aware that a similar problem can occur if all slaves | |
1841 | are released from a bond that still has one or more VLAN interfaces on | |
1842 | top of it. When a new slave is added, the bonding interface will | |
1843 | obtain its hardware address from the first slave, which might not | |
1844 | match the hardware address of the VLAN interfaces (which was | |
1845 | ultimately copied from an earlier slave). | |
1846 | ||
1847 | There are two methods to insure that the VLAN device operates | |
1848 | with the correct hardware address if all slaves are removed from a | |
1849 | bond interface: | |
1850 | ||
1851 | 1. Remove all VLAN interfaces then recreate them | |
1852 | ||
1853 | 2. Set the bonding interface's hardware address so that it | |
1854 | matches the hardware address of the VLAN interfaces. | |
1855 | ||
1856 | Note that changing a VLAN interface's HW address would set the | |
00354cfb | 1857 | underlying device -- i.e. the bonding interface -- to promiscuous |
1da177e4 LT |
1858 | mode, which might not be what you want. |
1859 | ||
1860 | ||
6224e01d | 1861 | 7. Link Monitoring |
1da177e4 LT |
1862 | ================== |
1863 | ||
1864 | The bonding driver at present supports two schemes for | |
1865 | monitoring a slave device's link state: the ARP monitor and the MII | |
1866 | monitor. | |
1867 | ||
1868 | At the present time, due to implementation restrictions in the | |
1869 | bonding driver itself, it is not possible to enable both ARP and MII | |
1870 | monitoring simultaneously. | |
1871 | ||
6224e01d | 1872 | 7.1 ARP Monitor Operation |
1da177e4 LT |
1873 | ------------------------- |
1874 | ||
1875 | The ARP monitor operates as its name suggests: it sends ARP | |
1876 | queries to one or more designated peer systems on the network, and | |
1877 | uses the response as an indication that the link is operating. This | |
1878 | gives some assurance that traffic is actually flowing to and from one | |
1879 | or more peers on the local network. | |
1880 | ||
1881 | The ARP monitor relies on the device driver itself to verify | |
1882 | that traffic is flowing. In particular, the driver must keep up to | |
1883 | date the last receive time, dev->last_rx, and transmit start time, | |
1884 | dev->trans_start. If these are not updated by the driver, then the | |
1885 | ARP monitor will immediately fail any slaves using that driver, and | |
1886 | those slaves will stay down. If networking monitoring (tcpdump, etc) | |
1887 | shows the ARP requests and replies on the network, then it may be that | |
1888 | your device driver is not updating last_rx and trans_start. | |
1889 | ||
6224e01d | 1890 | 7.2 Configuring Multiple ARP Targets |
1da177e4 LT |
1891 | ------------------------------------ |
1892 | ||
1893 | While ARP monitoring can be done with just one target, it can | |
1894 | be useful in a High Availability setup to have several targets to | |
1895 | monitor. In the case of just one target, the target itself may go | |
1896 | down or have a problem making it unresponsive to ARP requests. Having | |
1897 | an additional target (or several) increases the reliability of the ARP | |
1898 | monitoring. | |
1899 | ||
00354cfb | 1900 | Multiple ARP targets must be separated by commas as follows: |
1da177e4 LT |
1901 | |
1902 | # example options for ARP monitoring with three targets | |
1903 | alias bond0 bonding | |
1904 | options bond0 arp_interval=60 arp_ip_target=192.168.0.1,192.168.0.3,192.168.0.9 | |
1905 | ||
1906 | For just a single target the options would resemble: | |
1907 | ||
1908 | # example options for ARP monitoring with one target | |
1909 | alias bond0 bonding | |
1910 | options bond0 arp_interval=60 arp_ip_target=192.168.0.100 | |
1911 | ||
1912 | ||
6224e01d | 1913 | 7.3 MII Monitor Operation |
1da177e4 LT |
1914 | ------------------------- |
1915 | ||
1916 | The MII monitor monitors only the carrier state of the local | |
1917 | network interface. It accomplishes this in one of three ways: by | |
1918 | depending upon the device driver to maintain its carrier state, by | |
1919 | querying the device's MII registers, or by making an ethtool query to | |
1920 | the device. | |
1921 | ||
1922 | If the use_carrier module parameter is 1 (the default value), | |
1923 | then the MII monitor will rely on the driver for carrier state | |
1924 | information (via the netif_carrier subsystem). As explained in the | |
1925 | use_carrier parameter information, above, if the MII monitor fails to | |
1926 | detect carrier loss on the device (e.g., when the cable is physically | |
1927 | disconnected), it may be that the driver does not support | |
1928 | netif_carrier. | |
1929 | ||
1930 | If use_carrier is 0, then the MII monitor will first query the | |
1931 | device's (via ioctl) MII registers and check the link state. If that | |
1932 | request fails (not just that it returns carrier down), then the MII | |
1933 | monitor will make an ethtool ETHOOL_GLINK request to attempt to obtain | |
1934 | the same information. If both methods fail (i.e., the driver either | |
1935 | does not support or had some error in processing both the MII register | |
1936 | and ethtool requests), then the MII monitor will assume the link is | |
1937 | up. | |
1938 | ||
6224e01d | 1939 | 8. Potential Sources of Trouble |
1da177e4 LT |
1940 | =============================== |
1941 | ||
6224e01d | 1942 | 8.1 Adventures in Routing |
1da177e4 LT |
1943 | ------------------------- |
1944 | ||
1945 | When bonding is configured, it is important that the slave | |
6224e01d | 1946 | devices not have routes that supersede routes of the master (or, |
1da177e4 LT |
1947 | generally, not have routes at all). For example, suppose the bonding |
1948 | device bond0 has two slaves, eth0 and eth1, and the routing table is | |
1949 | as follows: | |
1950 | ||
1951 | Kernel IP routing table | |
1952 | Destination Gateway Genmask Flags MSS Window irtt Iface | |
1953 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth0 | |
1954 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 eth1 | |
1955 | 10.0.0.0 0.0.0.0 255.255.0.0 U 40 0 0 bond0 | |
1956 | 127.0.0.0 0.0.0.0 255.0.0.0 U 40 0 0 lo | |
1957 | ||
1958 | This routing configuration will likely still update the | |
1959 | receive/transmit times in the driver (needed by the ARP monitor), but | |
1960 | may bypass the bonding driver (because outgoing traffic to, in this | |
1961 | case, another host on network 10 would use eth0 or eth1 before bond0). | |
1962 | ||
1963 | The ARP monitor (and ARP itself) may become confused by this | |
1964 | configuration, because ARP requests (generated by the ARP monitor) | |
1965 | will be sent on one interface (bond0), but the corresponding reply | |
1966 | will arrive on a different interface (eth0). This reply looks to ARP | |
1967 | as an unsolicited ARP reply (because ARP matches replies on an | |
1968 | interface basis), and is discarded. The MII monitor is not affected | |
1969 | by the state of the routing table. | |
1970 | ||
1971 | The solution here is simply to insure that slaves do not have | |
1972 | routes of their own, and if for some reason they must, those routes do | |
6224e01d | 1973 | not supersede routes of their master. This should generally be the |
1da177e4 LT |
1974 | case, but unusual configurations or errant manual or automatic static |
1975 | route additions may cause trouble. | |
1976 | ||
6224e01d | 1977 | 8.2 Ethernet Device Renaming |
1da177e4 LT |
1978 | ---------------------------- |
1979 | ||
1980 | On systems with network configuration scripts that do not | |
1981 | associate physical devices directly with network interface names (so | |
1982 | that the same physical device always has the same "ethX" name), it may | |
970e2486 LDM |
1983 | be necessary to add some special logic to config files in |
1984 | /etc/modprobe.d/. | |
1da177e4 LT |
1985 | |
1986 | For example, given a modules.conf containing the following: | |
1987 | ||
1988 | alias bond0 bonding | |
1989 | options bond0 mode=some-mode miimon=50 | |
1990 | alias eth0 tg3 | |
1991 | alias eth1 tg3 | |
1992 | alias eth2 e1000 | |
1993 | alias eth3 e1000 | |
1994 | ||
1995 | If neither eth0 and eth1 are slaves to bond0, then when the | |
1996 | bond0 interface comes up, the devices may end up reordered. This | |
1997 | happens because bonding is loaded first, then its slave device's | |
1998 | drivers are loaded next. Since no other drivers have been loaded, | |
1999 | when the e1000 driver loads, it will receive eth0 and eth1 for its | |
2000 | devices, but the bonding configuration tries to enslave eth2 and eth3 | |
2001 | (which may later be assigned to the tg3 devices). | |
2002 | ||
2003 | Adding the following: | |
2004 | ||
2005 | add above bonding e1000 tg3 | |
2006 | ||
2007 | causes modprobe to load e1000 then tg3, in that order, when | |
2008 | bonding is loaded. This command is fully documented in the | |
2009 | modules.conf manual page. | |
2010 | ||
970e2486 LDM |
2011 | On systems utilizing modprobe an equivalent problem can occur. |
2012 | In this case, the following can be added to config files in | |
2013 | /etc/modprobe.d/ as: | |
1da177e4 | 2014 | |
78286cdf | 2015 | softdep bonding pre: tg3 e1000 |
1da177e4 | 2016 | |
970e2486 LDM |
2017 | This will load tg3 and e1000 modules before loading the bonding one. |
2018 | Full documentation on this can be found in the modprobe.d and modprobe | |
2019 | manual pages. | |
1da177e4 | 2020 | |
6224e01d | 2021 | 8.3. Painfully Slow Or No Failed Link Detection By Miimon |
1da177e4 LT |
2022 | --------------------------------------------------------- |
2023 | ||
2024 | By default, bonding enables the use_carrier option, which | |
2025 | instructs bonding to trust the driver to maintain carrier state. | |
2026 | ||
2027 | As discussed in the options section, above, some drivers do | |
2028 | not support the netif_carrier_on/_off link state tracking system. | |
2029 | With use_carrier enabled, bonding will always see these links as up, | |
2030 | regardless of their actual state. | |
2031 | ||
2032 | Additionally, other drivers do support netif_carrier, but do | |
2033 | not maintain it in real time, e.g., only polling the link state at | |
2034 | some fixed interval. In this case, miimon will detect failures, but | |
2035 | only after some long period of time has expired. If it appears that | |
2036 | miimon is very slow in detecting link failures, try specifying | |
2037 | use_carrier=0 to see if that improves the failure detection time. If | |
2038 | it does, then it may be that the driver checks the carrier state at a | |
2039 | fixed interval, but does not cache the MII register values (so the | |
2040 | use_carrier=0 method of querying the registers directly works). If | |
2041 | use_carrier=0 does not improve the failover, then the driver may cache | |
2042 | the registers, or the problem may be elsewhere. | |
2043 | ||
2044 | Also, remember that miimon only checks for the device's | |
2045 | carrier state. It has no way to determine the state of devices on or | |
2046 | beyond other ports of a switch, or if a switch is refusing to pass | |
2047 | traffic while still maintaining carrier on. | |
2048 | ||
6224e01d | 2049 | 9. SNMP agents |
1da177e4 LT |
2050 | =============== |
2051 | ||
2052 | If running SNMP agents, the bonding driver should be loaded | |
2053 | before any network drivers participating in a bond. This requirement | |
d533f671 | 2054 | is due to the interface index (ipAdEntIfIndex) being associated to |
1da177e4 LT |
2055 | the first interface found with a given IP address. That is, there is |
2056 | only one ipAdEntIfIndex for each IP address. For example, if eth0 and | |
2057 | eth1 are slaves of bond0 and the driver for eth0 is loaded before the | |
2058 | bonding driver, the interface for the IP address will be associated | |
2059 | with the eth0 interface. This configuration is shown below, the IP | |
2060 | address 192.168.1.1 has an interface index of 2 which indexes to eth0 | |
2061 | in the ifDescr table (ifDescr.2). | |
2062 | ||
2063 | interfaces.ifTable.ifEntry.ifDescr.1 = lo | |
2064 | interfaces.ifTable.ifEntry.ifDescr.2 = eth0 | |
2065 | interfaces.ifTable.ifEntry.ifDescr.3 = eth1 | |
2066 | interfaces.ifTable.ifEntry.ifDescr.4 = eth2 | |
2067 | interfaces.ifTable.ifEntry.ifDescr.5 = eth3 | |
2068 | interfaces.ifTable.ifEntry.ifDescr.6 = bond0 | |
2069 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 5 | |
2070 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2 | |
2071 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 4 | |
2072 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1 | |
2073 | ||
2074 | This problem is avoided by loading the bonding driver before | |
2075 | any network drivers participating in a bond. Below is an example of | |
2076 | loading the bonding driver first, the IP address 192.168.1.1 is | |
2077 | correctly associated with ifDescr.2. | |
2078 | ||
2079 | interfaces.ifTable.ifEntry.ifDescr.1 = lo | |
2080 | interfaces.ifTable.ifEntry.ifDescr.2 = bond0 | |
2081 | interfaces.ifTable.ifEntry.ifDescr.3 = eth0 | |
2082 | interfaces.ifTable.ifEntry.ifDescr.4 = eth1 | |
2083 | interfaces.ifTable.ifEntry.ifDescr.5 = eth2 | |
2084 | interfaces.ifTable.ifEntry.ifDescr.6 = eth3 | |
2085 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 6 | |
2086 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2 | |
2087 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 5 | |
2088 | ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1 | |
2089 | ||
2090 | While some distributions may not report the interface name in | |
2091 | ifDescr, the association between the IP address and IfIndex remains | |
2092 | and SNMP functions such as Interface_Scan_Next will report that | |
2093 | association. | |
2094 | ||
6224e01d | 2095 | 10. Promiscuous mode |
1da177e4 LT |
2096 | ==================== |
2097 | ||
2098 | When running network monitoring tools, e.g., tcpdump, it is | |
2099 | common to enable promiscuous mode on the device, so that all traffic | |
2100 | is seen (instead of seeing only traffic destined for the local host). | |
2101 | The bonding driver handles promiscuous mode changes to the bonding | |
00354cfb | 2102 | master device (e.g., bond0), and propagates the setting to the slave |
1da177e4 LT |
2103 | devices. |
2104 | ||
2105 | For the balance-rr, balance-xor, broadcast, and 802.3ad modes, | |
00354cfb | 2106 | the promiscuous mode setting is propagated to all slaves. |
1da177e4 LT |
2107 | |
2108 | For the active-backup, balance-tlb and balance-alb modes, the | |
00354cfb | 2109 | promiscuous mode setting is propagated only to the active slave. |
1da177e4 LT |
2110 | |
2111 | For balance-tlb mode, the active slave is the slave currently | |
2112 | receiving inbound traffic. | |
2113 | ||
2114 | For balance-alb mode, the active slave is the slave used as a | |
2115 | "primary." This slave is used for mode-specific control traffic, for | |
2116 | sending to peers that are unassigned or if the load is unbalanced. | |
2117 | ||
2118 | For the active-backup, balance-tlb and balance-alb modes, when | |
2119 | the active slave changes (e.g., due to a link failure), the | |
00354cfb | 2120 | promiscuous setting will be propagated to the new active slave. |
1da177e4 | 2121 | |
6224e01d | 2122 | 11. Configuring Bonding for High Availability |
00354cfb | 2123 | ============================================= |
1da177e4 LT |
2124 | |
2125 | High Availability refers to configurations that provide | |
2126 | maximum network availability by having redundant or backup devices, | |
00354cfb JV |
2127 | links or switches between the host and the rest of the world. The |
2128 | goal is to provide the maximum availability of network connectivity | |
2129 | (i.e., the network always works), even though other configurations | |
2130 | could provide higher throughput. | |
1da177e4 | 2131 | |
6224e01d | 2132 | 11.1 High Availability in a Single Switch Topology |
1da177e4 LT |
2133 | -------------------------------------------------- |
2134 | ||
00354cfb JV |
2135 | If two hosts (or a host and a single switch) are directly |
2136 | connected via multiple physical links, then there is no availability | |
2137 | penalty to optimizing for maximum bandwidth. In this case, there is | |
2138 | only one switch (or peer), so if it fails, there is no alternative | |
2139 | access to fail over to. Additionally, the bonding load balance modes | |
2140 | support link monitoring of their members, so if individual links fail, | |
2141 | the load will be rebalanced across the remaining devices. | |
2142 | ||
f8b72d36 | 2143 | See Section 12, "Configuring Bonding for Maximum Throughput" |
00354cfb JV |
2144 | for information on configuring bonding with one peer device. |
2145 | ||
6224e01d | 2146 | 11.2 High Availability in a Multiple Switch Topology |
00354cfb JV |
2147 | ---------------------------------------------------- |
2148 | ||
2149 | With multiple switches, the configuration of bonding and the | |
2150 | network changes dramatically. In multiple switch topologies, there is | |
2151 | a trade off between network availability and usable bandwidth. | |
2152 | ||
2153 | Below is a sample network, configured to maximize the | |
2154 | availability of the network: | |
1da177e4 | 2155 | |
00354cfb JV |
2156 | | | |
2157 | |port3 port3| | |
2158 | +-----+----+ +-----+----+ | |
2159 | | |port2 ISL port2| | | |
2160 | | switch A +--------------------------+ switch B | | |
2161 | | | | | | |
2162 | +-----+----+ +-----++---+ | |
2163 | |port1 port1| | |
2164 | | +-------+ | | |
2165 | +-------------+ host1 +---------------+ | |
2166 | eth0 +-------+ eth1 | |
1da177e4 | 2167 | |
00354cfb JV |
2168 | In this configuration, there is a link between the two |
2169 | switches (ISL, or inter switch link), and multiple ports connecting to | |
2170 | the outside world ("port3" on each switch). There is no technical | |
2171 | reason that this could not be extended to a third switch. | |
1da177e4 | 2172 | |
6224e01d | 2173 | 11.2.1 HA Bonding Mode Selection for Multiple Switch Topology |
00354cfb | 2174 | ------------------------------------------------------------- |
1da177e4 | 2175 | |
00354cfb JV |
2176 | In a topology such as the example above, the active-backup and |
2177 | broadcast modes are the only useful bonding modes when optimizing for | |
2178 | availability; the other modes require all links to terminate on the | |
2179 | same peer for them to behave rationally. | |
2180 | ||
2181 | active-backup: This is generally the preferred mode, particularly if | |
2182 | the switches have an ISL and play together well. If the | |
2183 | network configuration is such that one switch is specifically | |
2184 | a backup switch (e.g., has lower capacity, higher cost, etc), | |
2185 | then the primary option can be used to insure that the | |
2186 | preferred link is always used when it is available. | |
2187 | ||
2188 | broadcast: This mode is really a special purpose mode, and is suitable | |
2189 | only for very specific needs. For example, if the two | |
2190 | switches are not connected (no ISL), and the networks beyond | |
2191 | them are totally independent. In this case, if it is | |
2192 | necessary for some specific one-way traffic to reach both | |
2193 | independent networks, then the broadcast mode may be suitable. | |
2194 | ||
6224e01d | 2195 | 11.2.2 HA Link Monitoring Selection for Multiple Switch Topology |
00354cfb JV |
2196 | ---------------------------------------------------------------- |
2197 | ||
2198 | The choice of link monitoring ultimately depends upon your | |
2199 | switch. If the switch can reliably fail ports in response to other | |
2200 | failures, then either the MII or ARP monitors should work. For | |
2201 | example, in the above example, if the "port3" link fails at the remote | |
2202 | end, the MII monitor has no direct means to detect this. The ARP | |
2203 | monitor could be configured with a target at the remote end of port3, | |
2204 | thus detecting that failure without switch support. | |
2205 | ||
2206 | In general, however, in a multiple switch topology, the ARP | |
2207 | monitor can provide a higher level of reliability in detecting end to | |
2208 | end connectivity failures (which may be caused by the failure of any | |
2209 | individual component to pass traffic for any reason). Additionally, | |
2210 | the ARP monitor should be configured with multiple targets (at least | |
2211 | one for each switch in the network). This will insure that, | |
2212 | regardless of which switch is active, the ARP monitor has a suitable | |
2213 | target to query. | |
2214 | ||
9a6c6867 JV |
2215 | Note, also, that of late many switches now support a functionality |
2216 | generally referred to as "trunk failover." This is a feature of the | |
2217 | switch that causes the link state of a particular switch port to be set | |
2218 | down (or up) when the state of another switch port goes down (or up). | |
19f59460 | 2219 | Its purpose is to propagate link failures from logically "exterior" ports |
9a6c6867 JV |
2220 | to the logically "interior" ports that bonding is able to monitor via |
2221 | miimon. Availability and configuration for trunk failover varies by | |
2222 | switch, but this can be a viable alternative to the ARP monitor when using | |
2223 | suitable switches. | |
00354cfb | 2224 | |
6224e01d | 2225 | 12. Configuring Bonding for Maximum Throughput |
00354cfb JV |
2226 | ============================================== |
2227 | ||
6224e01d | 2228 | 12.1 Maximizing Throughput in a Single Switch Topology |
00354cfb JV |
2229 | ------------------------------------------------------ |
2230 | ||
2231 | In a single switch configuration, the best method to maximize | |
2232 | throughput depends upon the application and network environment. The | |
2233 | various load balancing modes each have strengths and weaknesses in | |
2234 | different environments, as detailed below. | |
2235 | ||
2236 | For this discussion, we will break down the topologies into | |
2237 | two categories. Depending upon the destination of most traffic, we | |
2238 | categorize them into either "gatewayed" or "local" configurations. | |
2239 | ||
2240 | In a gatewayed configuration, the "switch" is acting primarily | |
2241 | as a router, and the majority of traffic passes through this router to | |
2242 | other networks. An example would be the following: | |
2243 | ||
2244 | ||
2245 | +----------+ +----------+ | |
2246 | | |eth0 port1| | to other networks | |
2247 | | Host A +---------------------+ router +-------------------> | |
2248 | | +---------------------+ | Hosts B and C are out | |
2249 | | |eth1 port2| | here somewhere | |
2250 | +----------+ +----------+ | |
2251 | ||
2252 | The router may be a dedicated router device, or another host | |
2253 | acting as a gateway. For our discussion, the important point is that | |
2254 | the majority of traffic from Host A will pass through the router to | |
2255 | some other network before reaching its final destination. | |
2256 | ||
2257 | In a gatewayed network configuration, although Host A may | |
2258 | communicate with many other systems, all of its traffic will be sent | |
2259 | and received via one other peer on the local network, the router. | |
2260 | ||
2261 | Note that the case of two systems connected directly via | |
2262 | multiple physical links is, for purposes of configuring bonding, the | |
2263 | same as a gatewayed configuration. In that case, it happens that all | |
2264 | traffic is destined for the "gateway" itself, not some other network | |
2265 | beyond the gateway. | |
2266 | ||
2267 | In a local configuration, the "switch" is acting primarily as | |
2268 | a switch, and the majority of traffic passes through this switch to | |
2269 | reach other stations on the same network. An example would be the | |
2270 | following: | |
2271 | ||
2272 | +----------+ +----------+ +--------+ | |
2273 | | |eth0 port1| +-------+ Host B | | |
2274 | | Host A +------------+ switch |port3 +--------+ | |
2275 | | +------------+ | +--------+ | |
2276 | | |eth1 port2| +------------------+ Host C | | |
2277 | +----------+ +----------+port4 +--------+ | |
2278 | ||
2279 | ||
2280 | Again, the switch may be a dedicated switch device, or another | |
2281 | host acting as a gateway. For our discussion, the important point is | |
2282 | that the majority of traffic from Host A is destined for other hosts | |
2283 | on the same local network (Hosts B and C in the above example). | |
2284 | ||
2285 | In summary, in a gatewayed configuration, traffic to and from | |
2286 | the bonded device will be to the same MAC level peer on the network | |
2287 | (the gateway itself, i.e., the router), regardless of its final | |
2288 | destination. In a local configuration, traffic flows directly to and | |
2289 | from the final destinations, thus, each destination (Host B, Host C) | |
2290 | will be addressed directly by their individual MAC addresses. | |
2291 | ||
2292 | This distinction between a gatewayed and a local network | |
2293 | configuration is important because many of the load balancing modes | |
2294 | available use the MAC addresses of the local network source and | |
2295 | destination to make load balancing decisions. The behavior of each | |
2296 | mode is described below. | |
2297 | ||
2298 | ||
6224e01d | 2299 | 12.1.1 MT Bonding Mode Selection for Single Switch Topology |
00354cfb | 2300 | ----------------------------------------------------------- |
1da177e4 LT |
2301 | |
2302 | This configuration is the easiest to set up and to understand, | |
2303 | although you will have to decide which bonding mode best suits your | |
00354cfb | 2304 | needs. The trade offs for each mode are detailed below: |
1da177e4 LT |
2305 | |
2306 | balance-rr: This mode is the only mode that will permit a single | |
2307 | TCP/IP connection to stripe traffic across multiple | |
2308 | interfaces. It is therefore the only mode that will allow a | |
2309 | single TCP/IP stream to utilize more than one interface's | |
2310 | worth of throughput. This comes at a cost, however: the | |
9a6c6867 | 2311 | striping generally results in peer systems receiving packets out |
1da177e4 LT |
2312 | of order, causing TCP/IP's congestion control system to kick |
2313 | in, often by retransmitting segments. | |
2314 | ||
2315 | It is possible to adjust TCP/IP's congestion limits by | |
2316 | altering the net.ipv4.tcp_reordering sysctl parameter. The | |
dca145ff ED |
2317 | usual default value is 3. But keep in mind TCP stack is able |
2318 | to automatically increase this when it detects reorders. | |
1da177e4 | 2319 | |
9a6c6867 JV |
2320 | Note that the fraction of packets that will be delivered out of |
2321 | order is highly variable, and is unlikely to be zero. The level | |
2322 | of reordering depends upon a variety of factors, including the | |
2323 | networking interfaces, the switch, and the topology of the | |
2324 | configuration. Speaking in general terms, higher speed network | |
2325 | cards produce more reordering (due to factors such as packet | |
2326 | coalescing), and a "many to many" topology will reorder at a | |
2327 | higher rate than a "many slow to one fast" configuration. | |
2328 | ||
2329 | Many switches do not support any modes that stripe traffic | |
2330 | (instead choosing a port based upon IP or MAC level addresses); | |
2331 | for those devices, traffic for a particular connection flowing | |
2332 | through the switch to a balance-rr bond will not utilize greater | |
2333 | than one interface's worth of bandwidth. | |
00354cfb | 2334 | |
1da177e4 LT |
2335 | If you are utilizing protocols other than TCP/IP, UDP for |
2336 | example, and your application can tolerate out of order | |
2337 | delivery, then this mode can allow for single stream datagram | |
2338 | performance that scales near linearly as interfaces are added | |
2339 | to the bond. | |
2340 | ||
2341 | This mode requires the switch to have the appropriate ports | |
2342 | configured for "etherchannel" or "trunking." | |
2343 | ||
2344 | active-backup: There is not much advantage in this network topology to | |
2345 | the active-backup mode, as the inactive backup devices are all | |
2346 | connected to the same peer as the primary. In this case, a | |
2347 | load balancing mode (with link monitoring) will provide the | |
2348 | same level of network availability, but with increased | |
00354cfb JV |
2349 | available bandwidth. On the plus side, active-backup mode |
2350 | does not require any configuration of the switch, so it may | |
2351 | have value if the hardware available does not support any of | |
2352 | the load balance modes. | |
1da177e4 LT |
2353 | |
2354 | balance-xor: This mode will limit traffic such that packets destined | |
2355 | for specific peers will always be sent over the same | |
2356 | interface. Since the destination is determined by the MAC | |
00354cfb JV |
2357 | addresses involved, this mode works best in a "local" network |
2358 | configuration (as described above), with destinations all on | |
2359 | the same local network. This mode is likely to be suboptimal | |
2360 | if all your traffic is passed through a single router (i.e., a | |
2361 | "gatewayed" network configuration, as described above). | |
2362 | ||
2363 | As with balance-rr, the switch ports need to be configured for | |
1da177e4 LT |
2364 | "etherchannel" or "trunking." |
2365 | ||
2366 | broadcast: Like active-backup, there is not much advantage to this | |
2367 | mode in this type of network topology. | |
2368 | ||
2369 | 802.3ad: This mode can be a good choice for this type of network | |
2370 | topology. The 802.3ad mode is an IEEE standard, so all peers | |
2371 | that implement 802.3ad should interoperate well. The 802.3ad | |
2372 | protocol includes automatic configuration of the aggregates, | |
2373 | so minimal manual configuration of the switch is needed | |
2374 | (typically only to designate that some set of devices is | |
00354cfb JV |
2375 | available for 802.3ad). The 802.3ad standard also mandates |
2376 | that frames be delivered in order (within certain limits), so | |
2377 | in general single connections will not see misordering of | |
1da177e4 LT |
2378 | packets. The 802.3ad mode does have some drawbacks: the |
2379 | standard mandates that all devices in the aggregate operate at | |
2380 | the same speed and duplex. Also, as with all bonding load | |
2381 | balance modes other than balance-rr, no single connection will | |
2382 | be able to utilize more than a single interface's worth of | |
00354cfb JV |
2383 | bandwidth. |
2384 | ||
2385 | Additionally, the linux bonding 802.3ad implementation | |
92abf750 JX |
2386 | distributes traffic by peer (using an XOR of MAC addresses |
2387 | and packet type ID), so in a "gatewayed" configuration, all | |
2388 | outgoing traffic will generally use the same device. Incoming | |
2389 | traffic may also end up on a single device, but that is | |
2390 | dependent upon the balancing policy of the peer's 8023.ad | |
2391 | implementation. In a "local" configuration, traffic will be | |
2392 | distributed across the devices in the bond. | |
00354cfb JV |
2393 | |
2394 | Finally, the 802.3ad mode mandates the use of the MII monitor, | |
2395 | therefore, the ARP monitor is not available in this mode. | |
2396 | ||
2397 | balance-tlb: The balance-tlb mode balances outgoing traffic by peer. | |
2398 | Since the balancing is done according to MAC address, in a | |
2399 | "gatewayed" configuration (as described above), this mode will | |
2400 | send all traffic across a single device. However, in a | |
2401 | "local" network configuration, this mode balances multiple | |
2402 | local network peers across devices in a vaguely intelligent | |
2403 | manner (not a simple XOR as in balance-xor or 802.3ad mode), | |
2404 | so that mathematically unlucky MAC addresses (i.e., ones that | |
2405 | XOR to the same value) will not all "bunch up" on a single | |
2406 | interface. | |
2407 | ||
2408 | Unlike 802.3ad, interfaces may be of differing speeds, and no | |
2409 | special switch configuration is required. On the down side, | |
2410 | in this mode all incoming traffic arrives over a single | |
2411 | interface, this mode requires certain ethtool support in the | |
2412 | network device driver of the slave interfaces, and the ARP | |
2413 | monitor is not available. | |
2414 | ||
2415 | balance-alb: This mode is everything that balance-tlb is, and more. | |
2416 | It has all of the features (and restrictions) of balance-tlb, | |
2417 | and will also balance incoming traffic from local network | |
2418 | peers (as described in the Bonding Module Options section, | |
2419 | above). | |
2420 | ||
2421 | The only additional down side to this mode is that the network | |
2422 | device driver must support changing the hardware address while | |
2423 | the device is open. | |
2424 | ||
6224e01d | 2425 | 12.1.2 MT Link Monitoring for Single Switch Topology |
00354cfb | 2426 | ---------------------------------------------------- |
1da177e4 LT |
2427 | |
2428 | The choice of link monitoring may largely depend upon which | |
2429 | mode you choose to use. The more advanced load balancing modes do not | |
2430 | support the use of the ARP monitor, and are thus restricted to using | |
00354cfb JV |
2431 | the MII monitor (which does not provide as high a level of end to end |
2432 | assurance as the ARP monitor). | |
2433 | ||
6224e01d | 2434 | 12.2 Maximum Throughput in a Multiple Switch Topology |
00354cfb JV |
2435 | ----------------------------------------------------- |
2436 | ||
2437 | Multiple switches may be utilized to optimize for throughput | |
2438 | when they are configured in parallel as part of an isolated network | |
2439 | between two or more systems, for example: | |
2440 | ||
2441 | +-----------+ | |
2442 | | Host A | | |
2443 | +-+---+---+-+ | |
2444 | | | | | |
2445 | +--------+ | +---------+ | |
2446 | | | | | |
2447 | +------+---+ +-----+----+ +-----+----+ | |
2448 | | Switch A | | Switch B | | Switch C | | |
2449 | +------+---+ +-----+----+ +-----+----+ | |
2450 | | | | | |
2451 | +--------+ | +---------+ | |
2452 | | | | | |
2453 | +-+---+---+-+ | |
2454 | | Host B | | |
2455 | +-----------+ | |
2456 | ||
2457 | In this configuration, the switches are isolated from one | |
2458 | another. One reason to employ a topology such as this is for an | |
2459 | isolated network with many hosts (a cluster configured for high | |
2460 | performance, for example), using multiple smaller switches can be more | |
2461 | cost effective than a single larger switch, e.g., on a network with 24 | |
2462 | hosts, three 24 port switches can be significantly less expensive than | |
2463 | a single 72 port switch. | |
2464 | ||
2465 | If access beyond the network is required, an individual host | |
2466 | can be equipped with an additional network device connected to an | |
2467 | external network; this host then additionally acts as a gateway. | |
2468 | ||
6224e01d | 2469 | 12.2.1 MT Bonding Mode Selection for Multiple Switch Topology |
1da177e4 LT |
2470 | ------------------------------------------------------------- |
2471 | ||
00354cfb JV |
2472 | In actual practice, the bonding mode typically employed in |
2473 | configurations of this type is balance-rr. Historically, in this | |
2474 | network configuration, the usual caveats about out of order packet | |
2475 | delivery are mitigated by the use of network adapters that do not do | |
2476 | any kind of packet coalescing (via the use of NAPI, or because the | |
2477 | device itself does not generate interrupts until some number of | |
2478 | packets has arrived). When employed in this fashion, the balance-rr | |
2479 | mode allows individual connections between two hosts to effectively | |
2480 | utilize greater than one interface's bandwidth. | |
1da177e4 | 2481 | |
6224e01d | 2482 | 12.2.2 MT Link Monitoring for Multiple Switch Topology |
00354cfb | 2483 | ------------------------------------------------------ |
1da177e4 | 2484 | |
00354cfb JV |
2485 | Again, in actual practice, the MII monitor is most often used |
2486 | in this configuration, as performance is given preference over | |
2487 | availability. The ARP monitor will function in this topology, but its | |
2488 | advantages over the MII monitor are mitigated by the volume of probes | |
2489 | needed as the number of systems involved grows (remember that each | |
2490 | host in the network is configured with bonding). | |
1da177e4 | 2491 | |
6224e01d | 2492 | 13. Switch Behavior Issues |
00354cfb | 2493 | ========================== |
1da177e4 | 2494 | |
6224e01d | 2495 | 13.1 Link Establishment and Failover Delays |
00354cfb JV |
2496 | ------------------------------------------- |
2497 | ||
2498 | Some switches exhibit undesirable behavior with regard to the | |
2499 | timing of link up and down reporting by the switch. | |
1da177e4 LT |
2500 | |
2501 | First, when a link comes up, some switches may indicate that | |
2502 | the link is up (carrier available), but not pass traffic over the | |
2503 | interface for some period of time. This delay is typically due to | |
2504 | some type of autonegotiation or routing protocol, but may also occur | |
2505 | during switch initialization (e.g., during recovery after a switch | |
2506 | failure). If you find this to be a problem, specify an appropriate | |
2507 | value to the updelay bonding module option to delay the use of the | |
2508 | relevant interface(s). | |
2509 | ||
2510 | Second, some switches may "bounce" the link state one or more | |
2511 | times while a link is changing state. This occurs most commonly while | |
2512 | the switch is initializing. Again, an appropriate updelay value may | |
00354cfb | 2513 | help. |
1da177e4 LT |
2514 | |
2515 | Note that when a bonding interface has no active links, the | |
00354cfb JV |
2516 | driver will immediately reuse the first link that goes up, even if the |
2517 | updelay parameter has been specified (the updelay is ignored in this | |
2518 | case). If there are slave interfaces waiting for the updelay timeout | |
2519 | to expire, the interface that first went into that state will be | |
2520 | immediately reused. This reduces down time of the network if the | |
2521 | value of updelay has been overestimated, and since this occurs only in | |
2522 | cases with no connectivity, there is no additional penalty for | |
2523 | ignoring the updelay. | |
1da177e4 LT |
2524 | |
2525 | In addition to the concerns about switch timings, if your | |
2526 | switches take a long time to go into backup mode, it may be desirable | |
2527 | to not activate a backup interface immediately after a link goes down. | |
2528 | Failover may be delayed via the downdelay bonding module option. | |
2529 | ||
6224e01d | 2530 | 13.2 Duplicated Incoming Packets |
00354cfb JV |
2531 | -------------------------------- |
2532 | ||
9a6c6867 JV |
2533 | NOTE: Starting with version 3.0.2, the bonding driver has logic to |
2534 | suppress duplicate packets, which should largely eliminate this problem. | |
2535 | The following description is kept for reference. | |
2536 | ||
00354cfb JV |
2537 | It is not uncommon to observe a short burst of duplicated |
2538 | traffic when the bonding device is first used, or after it has been | |
2539 | idle for some period of time. This is most easily observed by issuing | |
2540 | a "ping" to some other host on the network, and noticing that the | |
2541 | output from ping flags duplicates (typically one per slave). | |
2542 | ||
2543 | For example, on a bond in active-backup mode with five slaves | |
2544 | all connected to one switch, the output may appear as follows: | |
2545 | ||
2546 | # ping -n 10.0.4.2 | |
2547 | PING 10.0.4.2 (10.0.4.2) from 10.0.3.10 : 56(84) bytes of data. | |
2548 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.7 ms | |
2549 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) | |
2550 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) | |
2551 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) | |
2552 | 64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!) | |
2553 | 64 bytes from 10.0.4.2: icmp_seq=2 ttl=64 time=0.216 ms | |
2554 | 64 bytes from 10.0.4.2: icmp_seq=3 ttl=64 time=0.267 ms | |
2555 | 64 bytes from 10.0.4.2: icmp_seq=4 ttl=64 time=0.222 ms | |
2556 | ||
2557 | This is not due to an error in the bonding driver, rather, it | |
2558 | is a side effect of how many switches update their MAC forwarding | |
2559 | tables. Initially, the switch does not associate the MAC address in | |
2560 | the packet with a particular switch port, and so it may send the | |
2561 | traffic to all ports until its MAC forwarding table is updated. Since | |
2562 | the interfaces attached to the bond may occupy multiple ports on a | |
2563 | single switch, when the switch (temporarily) floods the traffic to all | |
2564 | ports, the bond device receives multiple copies of the same packet | |
2565 | (one per slave device). | |
2566 | ||
2567 | The duplicated packet behavior is switch dependent, some | |
2568 | switches exhibit this, and some do not. On switches that display this | |
2569 | behavior, it can be induced by clearing the MAC forwarding table (on | |
2570 | most Cisco switches, the privileged command "clear mac address-table | |
2571 | dynamic" will accomplish this). | |
2572 | ||
6224e01d | 2573 | 14. Hardware Specific Considerations |
1da177e4 LT |
2574 | ==================================== |
2575 | ||
2576 | This section contains additional information for configuring | |
2577 | bonding on specific hardware platforms, or for interfacing bonding | |
2578 | with particular switches or other devices. | |
2579 | ||
6224e01d | 2580 | 14.1 IBM BladeCenter |
1da177e4 LT |
2581 | -------------------- |
2582 | ||
2583 | This applies to the JS20 and similar systems. | |
2584 | ||
2585 | On the JS20 blades, the bonding driver supports only | |
2586 | balance-rr, active-backup, balance-tlb and balance-alb modes. This is | |
2587 | largely due to the network topology inside the BladeCenter, detailed | |
2588 | below. | |
2589 | ||
2590 | JS20 network adapter information | |
2591 | -------------------------------- | |
2592 | ||
2593 | All JS20s come with two Broadcom Gigabit Ethernet ports | |
00354cfb JV |
2594 | integrated on the planar (that's "motherboard" in IBM-speak). In the |
2595 | BladeCenter chassis, the eth0 port of all JS20 blades is hard wired to | |
2596 | I/O Module #1; similarly, all eth1 ports are wired to I/O Module #2. | |
2597 | An add-on Broadcom daughter card can be installed on a JS20 to provide | |
2598 | two more Gigabit Ethernet ports. These ports, eth2 and eth3, are | |
2599 | wired to I/O Modules 3 and 4, respectively. | |
1da177e4 LT |
2600 | |
2601 | Each I/O Module may contain either a switch or a passthrough | |
2602 | module (which allows ports to be directly connected to an external | |
2603 | switch). Some bonding modes require a specific BladeCenter internal | |
2604 | network topology in order to function; these are detailed below. | |
2605 | ||
2606 | Additional BladeCenter-specific networking information can be | |
2607 | found in two IBM Redbooks (www.ibm.com/redbooks): | |
2608 | ||
2609 | "IBM eServer BladeCenter Networking Options" | |
2610 | "IBM eServer BladeCenter Layer 2-7 Network Switching" | |
2611 | ||
2612 | BladeCenter networking configuration | |
2613 | ------------------------------------ | |
2614 | ||
2615 | Because a BladeCenter can be configured in a very large number | |
2616 | of ways, this discussion will be confined to describing basic | |
2617 | configurations. | |
2618 | ||
00354cfb | 2619 | Normally, Ethernet Switch Modules (ESMs) are used in I/O |
1da177e4 LT |
2620 | modules 1 and 2. In this configuration, the eth0 and eth1 ports of a |
2621 | JS20 will be connected to different internal switches (in the | |
2622 | respective I/O modules). | |
2623 | ||
00354cfb JV |
2624 | A passthrough module (OPM or CPM, optical or copper, |
2625 | passthrough module) connects the I/O module directly to an external | |
2626 | switch. By using PMs in I/O module #1 and #2, the eth0 and eth1 | |
2627 | interfaces of a JS20 can be redirected to the outside world and | |
2628 | connected to a common external switch. | |
2629 | ||
2630 | Depending upon the mix of ESMs and PMs, the network will | |
2631 | appear to bonding as either a single switch topology (all PMs) or as a | |
2632 | multiple switch topology (one or more ESMs, zero or more PMs). It is | |
2633 | also possible to connect ESMs together, resulting in a configuration | |
2634 | much like the example in "High Availability in a Multiple Switch | |
2635 | Topology," above. | |
2636 | ||
2637 | Requirements for specific modes | |
2638 | ------------------------------- | |
2639 | ||
2640 | The balance-rr mode requires the use of passthrough modules | |
2641 | for devices in the bond, all connected to an common external switch. | |
2642 | That switch must be configured for "etherchannel" or "trunking" on the | |
1da177e4 LT |
2643 | appropriate ports, as is usual for balance-rr. |
2644 | ||
2645 | The balance-alb and balance-tlb modes will function with | |
2646 | either switch modules or passthrough modules (or a mix). The only | |
2647 | specific requirement for these modes is that all network interfaces | |
2648 | must be able to reach all destinations for traffic sent over the | |
2649 | bonding device (i.e., the network must converge at some point outside | |
2650 | the BladeCenter). | |
2651 | ||
2652 | The active-backup mode has no additional requirements. | |
2653 | ||
2654 | Link monitoring issues | |
2655 | ---------------------- | |
2656 | ||
2657 | When an Ethernet Switch Module is in place, only the ARP | |
2658 | monitor will reliably detect link loss to an external switch. This is | |
2659 | nothing unusual, but examination of the BladeCenter cabinet would | |
2660 | suggest that the "external" network ports are the ethernet ports for | |
2661 | the system, when it fact there is a switch between these "external" | |
2662 | ports and the devices on the JS20 system itself. The MII monitor is | |
2663 | only able to detect link failures between the ESM and the JS20 system. | |
2664 | ||
2665 | When a passthrough module is in place, the MII monitor does | |
2666 | detect failures to the "external" port, which is then directly | |
2667 | connected to the JS20 system. | |
2668 | ||
2669 | Other concerns | |
2670 | -------------- | |
2671 | ||
00354cfb | 2672 | The Serial Over LAN (SoL) link is established over the primary |
1da177e4 LT |
2673 | ethernet (eth0) only, therefore, any loss of link to eth0 will result |
2674 | in losing your SoL connection. It will not fail over with other | |
00354cfb JV |
2675 | network traffic, as the SoL system is beyond the control of the |
2676 | bonding driver. | |
1da177e4 LT |
2677 | |
2678 | It may be desirable to disable spanning tree on the switch | |
2679 | (either the internal Ethernet Switch Module, or an external switch) to | |
00354cfb | 2680 | avoid fail-over delay issues when using bonding. |
1da177e4 LT |
2681 | |
2682 | ||
6224e01d | 2683 | 15. Frequently Asked Questions |
1da177e4 LT |
2684 | ============================== |
2685 | ||
2686 | 1. Is it SMP safe? | |
2687 | ||
2688 | Yes. The old 2.0.xx channel bonding patch was not SMP safe. | |
2689 | The new driver was designed to be SMP safe from the start. | |
2690 | ||
2691 | 2. What type of cards will work with it? | |
2692 | ||
2693 | Any Ethernet type cards (you can even mix cards - a Intel | |
00354cfb JV |
2694 | EtherExpress PRO/100 and a 3com 3c905b, for example). For most modes, |
2695 | devices need not be of the same speed. | |
1da177e4 | 2696 | |
9a6c6867 JV |
2697 | Starting with version 3.2.1, bonding also supports Infiniband |
2698 | slaves in active-backup mode. | |
2699 | ||
1da177e4 LT |
2700 | 3. How many bonding devices can I have? |
2701 | ||
2702 | There is no limit. | |
2703 | ||
2704 | 4. How many slaves can a bonding device have? | |
2705 | ||
2706 | This is limited only by the number of network interfaces Linux | |
2707 | supports and/or the number of network cards you can place in your | |
2708 | system. | |
2709 | ||
2710 | 5. What happens when a slave link dies? | |
2711 | ||
2712 | If link monitoring is enabled, then the failing device will be | |
2713 | disabled. The active-backup mode will fail over to a backup link, and | |
2714 | other modes will ignore the failed link. The link will continue to be | |
2715 | monitored, and should it recover, it will rejoin the bond (in whatever | |
00354cfb JV |
2716 | manner is appropriate for the mode). See the sections on High |
2717 | Availability and the documentation for each mode for additional | |
2718 | information. | |
1da177e4 LT |
2719 | |
2720 | Link monitoring can be enabled via either the miimon or | |
00354cfb | 2721 | arp_interval parameters (described in the module parameters section, |
1da177e4 LT |
2722 | above). In general, miimon monitors the carrier state as sensed by |
2723 | the underlying network device, and the arp monitor (arp_interval) | |
2724 | monitors connectivity to another host on the local network. | |
2725 | ||
2726 | If no link monitoring is configured, the bonding driver will | |
2727 | be unable to detect link failures, and will assume that all links are | |
2728 | always available. This will likely result in lost packets, and a | |
00354cfb | 2729 | resulting degradation of performance. The precise performance loss |
1da177e4 LT |
2730 | depends upon the bonding mode and network configuration. |
2731 | ||
2732 | 6. Can bonding be used for High Availability? | |
2733 | ||
2734 | Yes. See the section on High Availability for details. | |
2735 | ||
2736 | 7. Which switches/systems does it work with? | |
2737 | ||
2738 | The full answer to this depends upon the desired mode. | |
2739 | ||
2740 | In the basic balance modes (balance-rr and balance-xor), it | |
2741 | works with any system that supports etherchannel (also called | |
2742 | trunking). Most managed switches currently available have such | |
00354cfb | 2743 | support, and many unmanaged switches as well. |
1da177e4 LT |
2744 | |
2745 | The advanced balance modes (balance-tlb and balance-alb) do | |
2746 | not have special switch requirements, but do need device drivers that | |
2747 | support specific features (described in the appropriate section under | |
00354cfb | 2748 | module parameters, above). |
1da177e4 | 2749 | |
6224e01d | 2750 | In 802.3ad mode, it works with systems that support IEEE |
1da177e4 LT |
2751 | 802.3ad Dynamic Link Aggregation. Most managed and many unmanaged |
2752 | switches currently available support 802.3ad. | |
2753 | ||
2754 | The active-backup mode should work with any Layer-II switch. | |
2755 | ||
2756 | 8. Where does a bonding device get its MAC address from? | |
2757 | ||
9a6c6867 JV |
2758 | When using slave devices that have fixed MAC addresses, or when |
2759 | the fail_over_mac option is enabled, the bonding device's MAC address is | |
2760 | the MAC address of the active slave. | |
2761 | ||
2762 | For other configurations, if not explicitly configured (with | |
2763 | ifconfig or ip link), the MAC address of the bonding device is taken from | |
2764 | its first slave device. This MAC address is then passed to all following | |
2765 | slaves and remains persistent (even if the first slave is removed) until | |
2766 | the bonding device is brought down or reconfigured. | |
1da177e4 LT |
2767 | |
2768 | If you wish to change the MAC address, you can set it with | |
00354cfb | 2769 | ifconfig or ip link: |
1da177e4 LT |
2770 | |
2771 | # ifconfig bond0 hw ether 00:11:22:33:44:55 | |
2772 | ||
00354cfb JV |
2773 | # ip link set bond0 address 66:77:88:99:aa:bb |
2774 | ||
1da177e4 LT |
2775 | The MAC address can be also changed by bringing down/up the |
2776 | device and then changing its slaves (or their order): | |
2777 | ||
2778 | # ifconfig bond0 down ; modprobe -r bonding | |
2779 | # ifconfig bond0 .... up | |
2780 | # ifenslave bond0 eth... | |
2781 | ||
2782 | This method will automatically take the address from the next | |
2783 | slave that is added. | |
2784 | ||
2785 | To restore your slaves' MAC addresses, you need to detach them | |
2786 | from the bond (`ifenslave -d bond0 eth0'). The bonding driver will | |
2787 | then restore the MAC addresses that the slaves had before they were | |
2788 | enslaved. | |
2789 | ||
00354cfb | 2790 | 16. Resources and Links |
1da177e4 LT |
2791 | ======================= |
2792 | ||
a23c37f1 | 2793 | The latest version of the bonding driver can be found in the latest |
1da177e4 LT |
2794 | version of the linux kernel, found on http://kernel.org |
2795 | ||
a23c37f1 NP |
2796 | The latest version of this document can be found in the latest kernel |
2797 | source (named Documentation/networking/bonding.txt). | |
00354cfb | 2798 | |
a23c37f1 NP |
2799 | Discussions regarding the usage of the bonding driver take place on the |
2800 | bonding-devel mailing list, hosted at sourceforge.net. If you have questions or | |
2801 | problems, post them to the list. The list address is: | |
1da177e4 LT |
2802 | |
2803 | bonding-devel@lists.sourceforge.net | |
2804 | ||
00354cfb JV |
2805 | The administrative interface (to subscribe or unsubscribe) can |
2806 | be found at: | |
1da177e4 | 2807 | |
00354cfb | 2808 | https://lists.sourceforge.net/lists/listinfo/bonding-devel |
1da177e4 | 2809 | |
f8b72d36 | 2810 | Discussions regarding the development of the bonding driver take place |
a23c37f1 NP |
2811 | on the main Linux network mailing list, hosted at vger.kernel.org. The list |
2812 | address is: | |
2813 | ||
2814 | netdev@vger.kernel.org | |
2815 | ||
2816 | The administrative interface (to subscribe or unsubscribe) can | |
2817 | be found at: | |
2818 | ||
2819 | http://vger.kernel.org/vger-lists.html#netdev | |
2820 | ||
1da177e4 | 2821 | Donald Becker's Ethernet Drivers and diag programs may be found at : |
0ea6e611 | 2822 | - http://web.archive.org/web/*/http://www.scyld.com/network/ |
1da177e4 LT |
2823 | |
2824 | You will also find a lot of information regarding Ethernet, NWay, MII, | |
2825 | etc. at www.scyld.com. | |
2826 | ||
2827 | -- END -- |