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Bonding Ethernet Interfaces in RHEL 6

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Red Hat Enterprise Linux allows administrators to bind multiple network interfaces together into a single channel using the bonding kernel module and a special network interface called a channel bonding interface. Channel bonding enables two or more network interfaces to act as one, simultaneously increasing the bandwidth and providing redundancy.

Channel bonding (also known as “Ethernet bonding”) is a computer networking arrangement in which two or more network interfaces on a host computer are combined for redundancy or increased throughput.

mode=0 (Balance-rr) – This mode provides load balancing and fault tolerance.
mode=1 (active-backup) – This mode provides fault tolerance.
mode=2 (balance-xor) – This mode provides load balancing and fault tolerance.
mode=3 (broadcast) – This mode provides fault tolerance.
mode=4 (802.3ad)This mode provides load balancing and fault tolerance.
mode=5 (balance-tlb) – Prerequisite: Ethtool support in the base drivers for retrieving the speed of each slave.
mode=6 (balance-alb) – Prerequisite: Ethtool support in the base drivers for retrieving the speed of each slave.

Note: Always append extra configuration in case of a rollback.


To create a channel bonding interface, create a file in the /etc/sysconfig/network-scripts/ directory called ifcfg-bond<N> , replacing <N> with the number for the interface, such as 0.

The contents of the file can be identical to whatever type of interface is getting bonded, such as an Ethernet interface. The only difference is that the DEVICE= directive must be bond<N> , replacing <N> with the number for the interface.

The following is a sample channel bonding configuration file, ifcfg-bond0:

BONDING_OPTS="<bonding parameters separated by spaces>"
After the channel bonding interface is created, the network interfaces to be bound together must be configured by adding the MASTER= and SLAVE= directives to their configuration files. The configuration files for each of the channel-bonded interfaces can be nearly identical.

For example, if two Ethernet interfaces are being channel bonded, both eth0 and eth1 may look like the following example:

In this example, replace <N> with the numerical value for the interface.

For a channel bonding interface to be valid, the kernel module must be loaded. To ensure that the module is loaded when the channel bonding interface is brought up, add the following line to /etc/modprobe.conf:

alias bond<N> bonding
Replace <N> with the number of the interface, such as 0.


Do not place parameters for the bonding kernel module in the /etc/modprobe.conf file. Instead, specify them as a space-separated list in the BONDING_OPTS="<bonding parameters>" directive in the ifcfg-bond<N> interface file.

The only exception is the debug parameter, which cannot be used on a per-device basis, and which should therefore be specified in /etc/modprobe.conf as follows:

options bonding debug=1
For further instructions and advice on configuring the bonding module, as well as to view the list of bonding parameters, refer to Section 45.5.2, “The Channel Bonding Module”.


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Configuring Interface Bonding on CentOS-RHEL-OEL 6.x Toki Winter

In my previous article I wrote about configuring configuring network interface bonding under Debian Wheezy. Here, I'll briefly outline the steps required to get the same configuration running under recent RHEL-flavoured distributions – namely CentOS 6.4 in my case.

I will be bonding eth0 and eth1 into a bond named bond0. Ensure that you're connected to your host via a console. I'll be using active-backup (i.e. failover) bonding, but there are other options available – see the Debian article for links to reference material for those.

First, create the ifcfg-bond0 configuration file:

RHEL 6 - New Network Bonding Configuration - FATMIN

September 12, 2011

Due to the fact that /etc/modprobe.conf has been deprecated in RHEL 6, the process of bonding network interfaces has changed a bit.

Now instead of defining your bond in your /etc/modprobe.conf, you define it in /etc/modprobe.d/bonding.conf. No changes in syntax.

alias bond0 bonding

Then in your ifconfig-bond0 file, you define your bonding mode. Note the quotes, and the fact that I explicitly typed out the bonding mode

Bonding Ethernet Interfaces in Linux

This short HOWTO will tell you how to 'bond' two (or more) physical ethernet interfaces together to look and act as a single interface under Linux.

It was originally written for Mandrakelinux users but it has also been tested on recent versions of Mandriva Linux.


This example assumes you have two interfaces and want to use them in a 'fail-over' setup, where if one cable dies, the kernel will automatically switch to using the other cable.. This setup is quite common on server hardware.

In /etc/modules.conf on a 2.4.x kernel, or in /etc/modprobe.conf on a 2.6.x kernel, you should have something similar to the following:

	alias eth0 e1000	# Intel GigE (pci) port 1
	alias eth1 e1000	# Intel GigE (pci) port 2

	alias bond0 bonding				# Kernel nic bonding driver
	alias bond1 bonding				# Another bonded interface
	options bond0 max_bonds=2 miimon=100 mode=1	# 100ms fail-over timer. Mode 1 = Active/Backup
	options bond1 miimon=100 mode=1			# Same for bond1 

You need the following files in /etc/sysconfig/network-scripts/ :


ifcfg-eth0 and ifcfg-eth1 should look similar to the following:


The DEVICE= section should reflect the interface the file relates to (ifcfg-eth1 should have DEVICE=eth1). The MASTER= section should indicate the bonded interface to be used. Assign both e1000 devices to bond0.

The bond0 file contains the actual IP address information:


Simply restarting the network service 'service network restart' should present you with a new 'bond0' interface. This is the interface you should see traffic going in and out of if youwere to tcpdump the interface.

You will also notice (using /sbin/ifconfig) that all of the ethX interfaces are also up, and also have IP addresses.

bond0     Link encap:Ethernet  HWaddr 00:04:23:61:06:30
	  inet addr:  Bcast:  Mask:
          inet6 addr: fe80::204:23ff:fe61:630/64 Scope:Link
          RX packets:240339580 errors:0 dropped:0 overruns:0 frame:0
          TX packets:264367658 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:3328878476 (3174.6 Mb)  TX bytes:2497930422 (2382.2 Mb)

eth0      Link encap:Ethernet  HWaddr 00:04:23:61:06:30
          inet6 addr: fe80::204:23ff:fe61:630/64 Scope:Link
          RX packets:43224057 errors:0 dropped:0 overruns:0 frame:0
          TX packets:50149177 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:965949319 (921.2 Mb)  TX bytes:3242163496 (3091.9 Mb)
          Base address:0xdcc0 Memory:fcfa0000-fcfc0000

eth1      Link encap:Ethernet  HWaddr 00:04:23:61:06:30
          inet6 addr: fe80::204:23ff:fe61:630/64 Scope:Link
          RX packets:197115526 errors:0 dropped:0 overruns:0 frame:0
          TX packets:214218484 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000
          RX bytes:2362929367 (2253.4 Mb)  TX bytes:3550735168 (3386.2 Mb)
          Base address:0xdc80 Memory:fcf80000-fcfa0000

In this example, we are using the fail-over mode. The eth device without NOARP is the current active SLAVE. You may notice that both ethX interfaces have high traffic counters. This is because the system has been up for around 200 days and at some point the interfaces swapped status.

For further reading, you should also read /usr/src/linux/Documentation/networking/bonding.txt which also gives the different bonding modes you can use. Some of these (like Etherchannel trunking) need compatible switches.

Debian - Ubuntu Linux Configure Network Bonding by nixCraft

Sep 4, 2011

Debian / Ubuntu Linux: Configure Network Bonding [ Teaming / Aggregating NIC ]

by NIX Craft on · 19 comments· LAST UPDATED September 6, 2011

in Debian Linux

NIC teaming is nothing but combining or aggregating multiple network connections in parallel. This is done to increase throughput, and to provide redundancy in case one of the links fails or Ethernet card fails. The Linux kernel comes with the bounding driver for aggregating multiple network interfaces into a single logical interface called bond0. In this tutorial, I will explain how to setup bonding under Debian Linux server to aggregate multiple Ethernet devices into a single link, to get higher data rates and link failover.

The instructions were tested using the following setup:
◾2 x PCI-e Gig NIC with jumbo frames.
◾RAID 6 w/ 5 enterprise grade 15k SAS hard disks.
◾Debian Linux 6.0.2 amd64

Please note that the following instructions should also work on Ubuntu Linux server.

RHEL: Linux Bond / Team Multiple Network Interfaces (NIC) Into a Single Interface by NIX Craft

April 3, 2006


Finally, today I had implemented NIC bounding (bind both NIC so that it works as a single device). 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. The following instructions were tested on:

  1. RHEL v4 / 5 / 6 amd64
  2. CentOS v5 / 6 amd64
  3. Fedora Linux 13 amd64 and up.
  4. 2 x PCI-e Gigabit Ethernet NICs with Jumbo Frames (MTU 9000)
  5. Hardware RAID-10 w/ SAS 15k enterprise grade hard disks.
  6. Gigabit switch with Jumbo Frame

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