Linux Network Interface Card Bonding

Channel Bonding helps two or more NIC card act as single. It increase the bandwidth and provides redundancy. In case on one physical NIC is down network traffic moves to another NIC card providing High Availability. We use bond driver to achieve it.

The following instructions are tested on:

OS: CentOS 6.7 installed on Virtual box Version 5.0.10 r104061

VM adapter settings: Bridged Adapter, Paravirtualized Network (virtio-net)

2 Ethernet Adapters eth0, eth1

Create bonding.conf file inside directory /etc/modprobe.d and add following linesalias bond0 bonding

Add following lines on the file bond0 interface configuration file /etc/sysconfig/network-scripts/ifcfg-bond0

DEVICE=bond0

IPADDR=192.168.1.254

NETWORK=192.168.1.0

NETMASK=255.255.255.0

USERCTL=no

BOOTPROTO=none

BONDING_OPTS="miimon=100 mode=1 fail_over_mac=1"

ONBOOT=yes

NM_CONTROLLED=no

Add following lines on file eth0 and eth1 configuration files
/etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0

USERCTL=no

ONBOOT=yes

MASTER=bond0

SLAVE=yes

BOOTPROTO=none

NM_CONTROLLED=no

/etc/sysconfig/network-scripts/ifcfg-eth1

DEVICE=eth1

USERCTL=no

ONBOOT=yes

MASTER=bond0

SLAVE=yes

BOOTPROTO=none

NM_CONTROLLED=no

Now restart network service

/etc/init.d/network restart

Verify failover

Ping IP 192.168.1.254 from another host.

ping 192.168.1.254

Keep watching the /var/log/message log file for interface down.

tail -f /var/log/message

Plug OFF cable from eth0. Message on the log file will be displayed as below

Dec  1 07:53:45 svn NetworkManager[1581]: <info> (eth0): carrier now OFF (device state 1)

Dec  1 07:53:45 svn kernel: bonding: bond0: link status definitely down for interface eth0, disabling it

Dec  1 07:53:45 svn kernel: bonding: bond0: making interface eth1 the new active one.

Plug ON cable on eth0

Dec  1 07:53:55 svn NetworkManager[1581]: <info> (eth0): carrier now ON (device state 1)

Dec  1 07:53:56 svn kernel: bonding: bond0: link status definitely up for interface eth0, 4294967295 Mbps full duplex.

Plug OFF cable on eth1

Dec  1 07:54:00 svn NetworkManager[1581]: <info> (eth1): carrier now OFF (device state 1)

Dec  1 07:54:00 svn kernel: bonding: bond0: link status definitely down for interface eth1, disabling it

Dec  1 07:54:00 svn kernel: bonding: bond0: making interface eth0 the new active one.

Plug ON cable on eth1

Dec  1 07:54:04 svn NetworkManager[1581]: <info> (eth1): carrier now ON (device state 1)

Dec  1 07:54:04 svn kernel: bonding: bond0: link status definitely up for interface eth1, 4294967295 Mbps full duplex.

[root@svn ~]# 

During cable Plug on and OFF, We can notice there is 0% Packet loss output from Ping result

--- 192.168.1.254 ping statistics ---

26 packets transmitted, 26 packets received, 0.0% packet loss

round-trip min/avg/max/stddev = 0.377/0.496/1.085/0.188 ms