Network bonding in Linux : How to setup?

Why we need to use bonding ?

Linux network Bonding is creation of a single bonded interface by combining 2 or more Ethernet interfaces. Its helps in high availability of your network interface and provides performance . Bonding is same as port trunking or teaming.


Bonding allows to aggregate multiple ports into a single group, effectively combining the bandwidth into a single connection. Bonding also allows you to create multi-gigabit pipes to transport traffic through the highest traffic areas of your network. For example, you can aggregate three megabits ports into a three-megabits trunk port. That is equivalent with having one interface with three megabytes speed


Steps for bonding in Linux:

Step 1 : Create a Bond0 Configuration File

Create the file ifcfg-bond0 with the IP address, netmask and gateway. Shown below is my test bonding config file.

$ cat /etc/sysconfig/network-scripts/ifcfg-bond0

DEVICE=bond0
IPADDR=192.168.1.5
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
USERCTL=no
BOOTPROTO=none
ONBOOT=yes

Step 2 :Modify eth0 and eth1 config files

Modify eth0, eth1  configuration as shown below. Comment out, or remove the ip address, netmask, gateway and hardware address from each one of these files, since settings should only come from the ifcfg-bond0 file above. Make sure to add the MASTER and SLAVE configuration in these files.

$ vi /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
BOOTPROTO=none
ONBOOT=yes
# Settings for Bond
MASTER=bond0
SLAVE=yes

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

DEVICE=eth1
BOOTPROTO=none
ONBOOT=yes
USERCTL=no
# Settings for bonding
MASTER=bond0
SLAVE=yes



Step 3 : Edit the config file for Bonding

Set the parameters for bond0 bonding kernel module. Select the network bonding mode based on you need, The below are modes available in bonding..

    mode=0 (Balance Round Robin)
    mode=1 (Active backup)
    mode=2 (Balance XOR)
    mode=3 (Broadcast)
    mode=4 (802.3ad)
    mode=5 (Balance TLB)
    mode=6 (Balance ALB)

Add the following lines to /etc/modprobe.conf

# bonding commands
alias bond0 bonding
options bond0 mode=1 miimon=100

Step 4 : Test the configuration

Load the bond driver module from the command prompt.

$ modprobe bonding

Step 5. Check the bonding status

Restart the network, or restart the computer.

$ service network restart # Or restart computer

5.1 - Check the bonding status:

$ cat /proc/net/bonding/bond0
Ethernet Channel Bonding Driver: v3.0.2 (March 23, 2006)

Bonding Mode: load balancing (round-robin)
MII Status: up
MII Polling Interval (ms): 100
Up Delay (ms): 200
Down Delay (ms): 200
Slave Interface: eth0
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:0c:29:c6:be:59
Slave Interface: eth1
MII Status: up
Link Failure Count: 0
Permanent HW addr: 00:0c:29:c6:be:63



Look at ifconfig -a and check that your bond0 interface is active. Thats it !!!

To verify whether the failover bonding works..

•     Do an ifdown eth0 and check /proc/net/bonding/bond0 and check the “Current Active slave”.
•     Do a continuous ping to the bond0 ipaddress from a different machine and do a ifdown the active interface. The ping should not break.

Samble output of ifconfig :


bond0     Link encap:Ethernet  HWaddr 00:0C:29:C6:BE:59
 inet addr:192.168.1.20  Bcast:192.168.1.255  Mask:255.255.255.0
 inet6 addr: fe80::200:ff:fe00:0/64 Scope:Link
 UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1
 RX packets:2804 errors:0 dropped:0 overruns:0 frame:0
 TX packets:1879 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:0
 RX bytes:250825 (244.9 KiB)  TX bytes:244683 (238.9 KiB)
eth0      Link encap:Ethernet  HWaddr 00:0C:29:C6:BE:59
 inet addr:192.168.1.20  Bcast:192.168.1.255  Mask:255.255.255.0
 inet6 addr: fe80::20c:29ff:fec6:be59/64 Scope:Link
 UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1
 RX packets:2809 errors:0 dropped:0 overruns:0 frame:0
 TX packets:1390 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1000
 RX bytes:251161 (245.2 KiB)  TX bytes:180289 (176.0 KiB)
 Interrupt:11 Base address:0x1400
eth1      Link encap:Ethernet  HWaddr 00:0C:29:C6:BE:59
 inet addr:192.168.1.20  Bcast:192.168.1.255  Mask:255.255.255.0
 inet6 addr: fe80::20c:29ff:fec6:be59/64 Scope:Link
 UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1
 RX packets:4 errors:0 dropped:0 overruns:0 frame:0
 TX packets:502 errors:0 dropped:0 overruns:0 carrier:0
 collisions:0 txqueuelen:1000
 RX bytes:258 (258.0 b)  TX bytes:66516 (64.9 KiB)
 Interrupt:10 Base address:0x1480