Topics: Networking, Red Hat / Linux

Enabling bonding in Linux

To enable "etherchannel" or "bonding" in Linux nomenclature:

  • Add these two lines to /etc/modprobe.conf:
    alias bond0 bonding
    options bond0 miimon=100 mode=1 primary=eth0
    Entry "mode=1" simply means active/standby. Entry "miimon" is the number in milliseconds to wait before determining a link dead (Change eth0 to match your primary device, if it is different. Blades sometimes have eth4 as the primary device).
  • In /etc/sysconfig/network-scripts create ifcfg-bond0 with the following (of course, change the network info to match your own):
  • Change ifcfg-eth0 and ifcfg-eth1 (or whatever they are) to resemble this:
    Leave the value of HWADDR to whatever it is in your file. This is important. It is this devices MAC Address.
  • Run /etc/init.d/network restart. You will want to do at least this part from the console, in case something goes wrong.
  • Once you get your "OK" and the prompt comes back, do an ifconfig -a. You should see bond0.
  • Make sure you can ping your default gateway. After that, all should be good.
Note: When making back up copies of the ifcfg-* files, you must either move the backup files out of this directory or change your backup copy strategy for these files. The primary network script that reads these files, basically runs: ls ifcg-*. It then creates an interface based on the part after the dash ("-"). So if you run, for example:
# cp ifcfg-eth0 ifcfg-eth0.bak
You will end up with an alias device of eth0 called eth0.bak. Instead do this:
# cp ifcfg-eth0 bak.$(date +%Y%m%d).ifcfg-eth0
That foils the configuration script and allows to keep backup/backout copies in the same directory with the working copies.

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