Channel Bonding Interfaces

Red Hat Enterprise Linux allows administrators to bind multiple network interfaces together into a single channel using the bonding kernel module and a special network interface called a channel bonding interface. Channel bonding enables two or more network interfaces to act as one, simultaneously increasing the bandwidth and providing redundancy.

To create a channel bonding interface, create a file in the /etc/sysconfig/network-scripts/ directory called ifcfg-bond, replacing with the number for the interface, such as 0.

The contents of the file can be identical to whatever type of interface is getting bonded, such as an Ethernet interface. The only difference is that the DEVICE= directive must be bond, replacing with the number for the interface.

The following is a sample channel bonding configuration file:

DEVICE=bond0 
BOOTPROTO=none 
ONBOOT=yes 
NETWORK=10.0.1.0 
NETMASK=255.255.255.0 
IPADDR=10.0.1.27 
USERCTL=no

After the channel bonding interface is created, the network interfaces to be bound together must be configured by adding the MASTER= and SLAVE= directives to their configuration files. The configuration files for each of the channel-bonded interfaces can be nearly identical.

For example, if two Ethernet interfaces are being channel bonded, both eth0 and eth1 may look like the following example:

DEVICE=eth 
BOOTPROTO=none 
ONBOOT=yes 
MASTER=bond0 
SLAVE=yes 
USERCTL=no

In this example, replace with the numerical value for the interface.

For a channel bonding interface to be valid, the kernel module must be loaded. To ensure that the module is loaded when the channel bonding interface is brought up, add the following line to /etc/modprobe.conf:

alias bond bonding

Replace with the number of the interface, such as 0. For each configured channel bonding interface, there must be a corresponding entry in /etc/modprobe.conf.

Once /etc/modprobe.conf is configured — and the channel bonding interface and network interfaces are configured — the ifup command can be used to bring up the channel bonding interface.