Network bonding refers to the combination of network interfaces on one host for redundancy and/or increased throughput. Redundancy is the key factor: we want to protect our virtualized environment from loss of service due to failure of a single physical link.
We will configure our network cards in “active/backup” configuration. This is a network bonding fallback configuration which means if one of your network cards fails all of the traffic will be instantly switched to the other, still working network card.
1. Install required packages
root@foo1:~# apt-get update
root@foo1:~# apt-get install ifenslave
2. Edit /etc/modules file
Edit /etc/modules file and add “bonding” at the end of it.
root@foo1:~# cat /etc/modules
# /etc/modules: kernel modules to load at boot time.
#
# This file contains the names of kernel modules that should be loaded
# at boot time, one per line. Lines beginning with “#” are ignored.
loop
lp
bonding
3. Stop networking
root@foo1:~# /etc/init.d/networking stop
4. Edit /etc/network/interfaces file
Edit /etc/network/interfaces file and configure bonding interface bond0. You also need to change existing eth interfaces to be known as slaves of bond interface by adding “bond-master bond0” to their configuration. There are a couple of bond interface options explained below. Mind the bold text!
root@foo1:~# cat /etc/network/interfaces
# This file describes the network interfaces available on your system
# and how to activate them. For more information, see interfaces(5).
# The loopback network interface
auto lo
iface lo inet loopback
# The primary network interface
auto eth0
iface eth0 inet manual
bond-master bond0
bond-primary eth0
# The secondary network interface
auto eth1
iface eth1 inet manual
bond-master bond0
# Bonding interface configuration
auto bond0
iface bond0 inet static
address 192.168.1.150
netmask 255.255.255.0
gateway 192.168.1.1
bond-slaves eth0 eth1
bond-miimon 100
bond-mode active-backup
5. Modprobe bonding
root@foo1:~# modprobe bonding
6. Start networking
root@foo1:~# /etc/init.d/networking start
7. Check the status of network bonding
As we can see below, bonding was successfully configured in active-backup mode. Slave interfaces are eth0 and eth1.
root@foo1:~# cat /proc/net/bonding/bond0
Bonding Mode: fault-tolerance (active-backup)
Primary Slave: eth0 (primary_reselect always)
Currently Active Slave: eth0
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 0
Down Delay (ms): 0
Slave Interface: eth0
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 08:00:27:a8:ab:ab
Slave queue ID: 0
Slave Interface: eth1
MII Status: up
Speed: 1000 Mbps
Duplex: full
Link Failure Count: 0
Permanent HW addr: 08:00:27:de:fd:85
Slave queue ID: 0
7. Check ifconfig
Again we see that all interfaces are up and running and bond0 interface has the assigned IP address. Network bonding on Ubuntu Server is working as expected.
