Bonding Multiple NICs

Overview
This tutorial will show you how to setup a bond where multiple network cards are combined to look like a single NIC for increased throughput and redundancy.

Ubuntu 10.04 or higher

 * Install ifenslave

sudo apt-get update && sudo apt-get install ifenslave

We are using a basic bonding mode 2. For other modes, please see: https://help.ubuntu.com/community/UbuntuBonding

We have had issues on Ubuntu 10.04 using mode 0, we have had better luck using mode 2

mode=0 (balance-rr) (See note above!)
Round-robin policy: Stripes traffic across multiple interfaces. This mode provides load balancing and fault tolerance. the striping generally results in peer systems receiving packets out of order, causing TCP/IP’s congestion control system to kick in, often by retransmitting segments.

mode=1 (active-backup)
Active-backup policy: Only one slave in the bond is active. A different slave becomes active if, and only if, the active slave fails. The bond’s MAC address is externally visible on only one port (network adapter) to avoid confusing the switch. This mode provides fault tolerance. The primary option affects the behavior of this mode.

mode=2 (balance-xor)
XOR policy: Transmit based on [(source MAC address XOR'd with destination MAC address) modulo slave count]. This selects the same slave for each destination MAC address. This mode provides load balancing and fault tolerance.

mode=3 (broadcast)
Broadcast policy: transmits everything on all slave interfaces. This mode provides fault tolerance.


 * Edit your interfaces file, /etc/network/interfaces.

auto lo iface lo inet loopback auto bond0 iface bond0 inet static bond-slaves none bond-mode 2 bond-miimon 100 address 192.168.1.50 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.0.255 gateway 192.168.1.1 hwaddress ether 00:AA:BB:CC:DD:EE auto eth0 iface eth0 inet manual bond-master bond0 bond-primary eth0 eth1 auto eth1 iface eth1 inet manual bond-master bond0 bond-primary eth0 eth1

hwaddress could be the MAC address of one of you network cards, this can be found by running:

ifconfig


 * Reboot your server

sudo reboot

CentOS / RedHat
Edit /etc/modprobe.conf and add the following (see the note above in the Ubuntu section about this type of bonding): alias bond0 bonding options bonding mode=0 miimon=100 downdelay=200 updelay=200

Create the file /etc/sysconfig/network-scripts/ifcfg-bond0 and add the following (substitute your server's IP address, netmask and gateway of course): DEVICE=bond0 BOOTPROTO=static ONBOOT=yes IPADDR= NETMASK= GATEWAY= TYPE=Ethernet
 * 1) Bonded interface

Edit the file /etc/sysconfig/network-scripts/ifcfg-eth0 so that it looks similar to this. This file should already exist, you're just editing out the IP address configuration. Preserve your server's MAC address if this file is already there to make things easier.

DEVICE=eth0 BOOTPROTO=none ONBOOT=yes HWADDR= MASTER=bond0 SLAVE=yes TYPE=Ethernet Edit /etc/sysconfig/network-scripts/ifcfg-eth1 and so on for each interface you want to bond together. All that's needed in the ifcfg script is what is shown above. Again, substitute your server's MAC addresses in place of the HWADDR listed above. Don't forget to change the DEVICE= line as well to correspond to the interface you're setting up (eth1, eth2, etc)