RHEL: Linux Bonding, Multiple Network Interfaces (NIC) Into a Single Interface

Bonding is nothing but Linux kernel feature that allows to aggregate multiple like interfaces (such as eth0, eth1) into a single virtual link such as bond0. The idea is pretty simple get higher data rates and as well as link failover. The following instructions were tested on:


RHEL v5 / 6,
CentOS v5 / 6.


 I am using Red Hat enterprise Linux version 5.0. 


Step - 1: Create a Bond0 Configuration File

Red Hat Enterprise Linux (and its clone such as CentOS) stores network configuration in /etc/sysconfig/network-scripts/ directory. First, you need to create a bond0 config file as follows:
# vi /etc/sysconfig/network-scripts/ifcfg-bond0Append the following linest:

 
DEVICE=bond0
IPADDR=192.168.1.20
NETWORK=192.168.1.0
NETMASK=255.255.255.0
USERCTL=no
BOOTPROTO=none
ONBOOT=yes
 

You need to replace IP address with your actual setup. Save and close the file.

Step - 2: Modify eth0 and eth1 config files

Open both configuration using a text editor such as vi/vim, and make sure file read as follows for eth0 interface
# vi /etc/sysconfig/network-scripts/ifcfg-eth0Modify/append directive as follows:
DEVICE=eth0
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=noneOpen eth1 configuration file using vi text editor, enter:
# vi /etc/sysconfig/network-scripts/ifcfg-eth1Make sure file read as follows for eth1 interface:
DEVICE=eth1
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=noneSave and close the file.

Step - 3: Load bond driver/module

Make sure bonding module is loaded when the channel-bonding interface (bond0) is brought up. You need to modify kernel modules configuration file:# vi /etc/modprobe.conf
Append following two lines:alias bond0 bonding
options bond0 mode=balance-alb miimon=100Save file and exit to shell prompt. You can learn more about all bounding options by clickinghere).

Step - 4: Test configuration

First, load the bonding module, enter:
# modprobe bonding
Restart the networking service in order to bring up bond0 interface, enter:
# service network restart# ifconfigMake sure everything is working. Type the following cat command to query the current status of Linux kernel bounding driver, enter:
# cat /proc/net/bonding/bond0