.. _Setting Up Network Bonding:

Setting Up Network Bonding
--------------------------

Bonding multiple network interfaces together provides the following benefits:

#. High network availability. If one of the interfaces fails, the traffic will be automatically routed to the working interface(s).

#. Higher network performance. For example, two Gigabit interfaces bonded together will deliver about 1.7 Gbit/s or 200 MB/s throughput. The required number of bonded storage network interfaces may depend on how many storage drives are on the node. For example, a rotational HDD can deliver up to 1 Gbit/s throughput.

To configure a bonding interface, do the following:

#. Create the ``/etc/modprobe.d/bonding.conf`` file containing the following line:

   alias bond0 bonding

#. Create the ``/etc/sysconfig/network-scripts/ifcfg-bond0`` file containing the following lines:

   ::

       DEVICE=bond0
       ONBOOT=yes
       BOOTPROTO=none
       IPV6INIT=no
       USERCTL=no
       BONDING_OPTS="mode=balance-xor xmit_hash_policy=layer3+4 miimon=300 downdelay=300 \
       updelay=300"
       NAME="Storage net0"
       NM_CONTROLLED=no
       IPADDR=xxx.xxx.xxx.xxx
       PREFIX=24

   .. note::
   
      #. Make sure to enter the correct values in the ``IPADDR`` and ``PREFIX`` lines.

      #. The ``balance-xor`` mode is recommended, because it offers both fault tolerance and better performance. For more details, see the documents listed below.

#. Make sure the configuration file of each Ethernet interface you want to bond (e.g., ``/etc/sysconfig/network-scripts/ifcfg-eth0``) contains the lines shown in this example:

   ::

       DEVICE="eth0"
       BOOTPROTO=none
       NM_CONTROLLED="no"
       ONBOOT="yes"
       TYPE="Ethernet"
       HWADDR=xx:xx:xx:xx:xx:xx
       MASTER=bond0
       SLAVE=yes
       USERCTL=no

#. Bring up the ``bond0`` interface:

   ::

       # ifup bond0

#. Use ``dmesg`` output to verify that ``bond0`` and its slave Ethernet interfaces are up and links are ready.

.. note:: More information on network bonding is provided in the *Red Hat Enterprise Linux Deployment Guide* and *Linux Ethernet Bonding Driver HOWTO.*