Summary

The concept of NIC Bonding (or sometimes called NIC Teaming) is that you have two NICs bonded together to appear as if they are the same physical device. I.e. They will both present the same Hardware (MAC) address. This is accomplished through the ifenslave utility, which enables the kernel to see/use only one device, while it sends out packtes via the two slave devices using a round-robbin scheduler.

Modules Involved: bonding, mii, nic_module (e100 in this example) Utilities: ifenslave, mii-tool

• Author: BJ Dierkes
• Originally Written: December 2nd, 2005
• Last Updated: July 24, 2008
• Contact: wdierkes [at] 5dollarwhitebox [dot] org

Preparation

Before attempting to bond two NICs, it is highly recommended that you verify the integrity and functionality of each NIC on its own. This document assumes that you've already done that. Using 'mii-tool' you should see something like the following:

testbox:/# mii-tool
eth0: negotiated 100baseTx-FD, link ok
eth1: negotiated 100baseTx-FD, link ok

In order for this to work, the kernel must have support for bonding devices. A few ways to check would be:

testbox:/# modprobe --list | grep -i bonding
/lib/modules/2.4.26-2-686/kernel/drivers/net/bonding/bonding.o

testbox:/# find /lib/modules/`uname -r` -iname bonding*
/lib/modules/2.4.26-2-686/kernel/drivers/net/bonding/bonding.o

NOTE: It has been brought to my attention that the mention of mii-tool was unclear. Previously the wording in the article referenced mii-tool as if it were required for bonding. This is not the case, I simply am using mii-tool in order to 'monitor' the state of the NICs during testing. Any tool that shows the state of the NICs links is fine.

I am using the mii-tool to monitor the interface state during testing. Therefore, when I unplug one interface I should see the link go down via mii-tool, and come back up when connected.

Second, your going to need to install the ifenslave utility.

testbox:/# apt-get update && apt-get install ifenslave
.......... removed standard output (nothing interesting)

Theres no configuration here, so that is that. Now we are ready for the configuration files.

Configuration Files

There are many different variations of this, but for now... this is how I did it to get it working.

vi /etc/modutils/aliases and add/edit the following:

alias bond0 bonding
alias eth0 e100
alias eth1 e100
options bonding mode=0 miimon=100

vi /etc/modutils/actions and add/edit the following:

probeall bond0 eth0 eth1 bonding

After editing the modprobe config files you need to run the command:

testbox# update-modules

vi /etc/network/interfaces and add/edit the following:

auto bond0
iface bond0 inet static
address 10.1.100.63
netmask 255.255.255.0
hwaddress ether 00:02:B3:48:50:2C
gateway 10.1.100.1
up ifenslave bond0 eth0 eth1
down ifenslave -d bond0 eth0 eth1

You do NOT set up entries for 'eth0' or 'eth1' outside of whats listed above under the 'bond0' entry. Bond0 will now be the interface that the kernel works with. Running an 'ifconfig' will show all three interface (bond0,eth0,eth1), all with the same MAC and IP addresses.

And thats basically it. Now, all you should need to do is load the bonding module and stop/start networking...

testbox:/# modprobe bonding
testbox:/# /etc/init.d/networking stop
testbox:/# /etc/init.d/networking start

Sometimes you might have to play with this a bit. For me I got a bunch of wierd errors at first... so I stopped networking, and then manually configured bond0 with ifconfig:

testbox:/# ifconfig bond0 10.1.100.63 netmask 255.255.255.0 up

Assuming that there were no errors, you should be able to test this out. Try and ping your IP address from another box. You'll notice both NICs responding to the ping requests back and forth (round robin). If you unplug eth0, you'll get an error the console the "eth0 has failed, eth1 becoming primary" or something like that (and visa versa if you unplug eth1). But you shouldn't drop any of the ping requests (or no more than a few), as it now has a redundant network connection.

In a higher end environment, you could plug each NIC into a separate switch (staying on the same VLAN) and further improve your high availability config... and so on and so forth.