RHEL: Linux Bond / Multiple Network Interfaces (NIC) Into a Single Interface

RHEL: Linux Bond / 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.

We will configure here bond0 virtual link on eth0 and eth1 NIC Cards on RHEL5.8 Server. It will also work on latest RHEL 6 version.

Bonding is mainly kernel feature of RHEL server which provides this functionality of load balancing and redundancy of link. The Bonding driver should be installed on server before configuring multiple NIC cards into a single bond virtual link.

Step #1: Create a Bond0 Configuration File

Red Hat Enterprise Linux (and its clone such as Cent OS) stores network configuration in /etc/sysconfig/network-scripts/ directory. First, you need to create a bond0 configuration file as follows:

# vi /etc/sysconfig/network-scripts/ifcfg-bond0
Append the following lines:

DEVICE=bond0

IPADDR=10.0.1.67

NETWORK=10.0.0.0

NETMASK=255.255.252.0

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-eth0
Modify/append directive as follows:
DEVICE=eth0
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none

Open eth1 configuration file using vi text editor, enter:
# vi /etc/sysconfig/network-scripts/ifcfg-eth1
Make sure file read as follows for eth1 interface:

DEVICE=eth1
USERCTL=no
ONBOOT=yes
MASTER=bond0
SLAVE=yes
BOOTPROTO=none


Save 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=100

Save file and exit to shell prompt.

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
Make 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

Sample outputs:

Bonding Mode: adaptive load balancing

Primary Slave: None

Currently Active Slave: eth1

MII Status: up

MII Polling Interval (ms): 100

Up Delay (ms): 0

Down Delay (ms): 0

Slave Interface: eth0

MII Status: down

Speed: Unknown

Duplex: Unknown

Link Failure Count: 0

Permanent HW addr: 10:1f:74:2f:8c:8c

Slave Interface: eth1

MII Status: up

Speed: 1000 Mbps

Duplex: full

Link Failure Count: 0

To list all network interfaces, Enter:
# ifconfig

Sample outputs:

bond0     Link encap:Ethernet  HWaddr 10:1F:74:2F:8C:8C

          inet addr:10.0.1.67  Bcast:10.0.15.255  Mask:255.255.240.0

          inet6 addr: 2002:dc9c:bfcf:5:121f:74ff:fe2f:8c8c/64 Scope:Global

          inet6 addr: fec0::5:121f:74ff:fe2f:8c8c/64 Scope:Site

          inet6 addr: fec0::a:121f:74ff:fe2f:8c8c/64 Scope:Site

          inet6 addr: 2002:dc9c:bfca:a:121f:74ff:fe2f:8c8c/64 Scope:Global

          inet6 addr: fe80::121f:74ff:fe2f:8c8c/64 Scope:Link

          UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1

          RX packets:4123683 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1658279 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:0

          RX bytes:2050975191 (1.9 GiB)  TX bytes:555880972 (530.1 MiB)

eth0      Link encap:Ethernet  HWaddr 10:1F:74:2F:8C:8E

          UP BROADCAST SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:0 errors:0 dropped:0 overruns:0 frame:0

          TX packets:0 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:0 (0.0 b)  TX bytes:0 (0.0 b)

          Interrupt:162 Memory:f4000000-f4012800

eth1      Link encap:Ethernet  HWaddr 10:1F:74:2F:8C:8C

          UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1

          RX packets:4123683 errors:0 dropped:0 overruns:0 frame:0

          TX packets:1658279 errors:0 dropped:0 overruns:0 carrier:0

          collisions:0 txqueuelen:1000

          RX bytes:2050975191 (1.9 GiB)  TX bytes:555880972 (530.1 MiB)

          Interrupt:170 Memory:f2000000-f2012800

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