User: Big Bob

Linux Channel Bonding Might help

On: Linux Failover?

We are trying to implement this same thing here on out production
network. EVERY machine has 2 connections to any subnet that it is
attached to. We are doing this to eliminate the single point of
failure for any one switch.

The trick is you want one NIC port to failover to the other. One way
to do this is to use the channel bonding stuff in the 2.2.15
kernel. (see linux/Documentation/networking/bonding.txt, or some
such).

This creates a virtual interface that you associate real interfaces
to. All real interfaces get the same MAC address and behave as one
virtual NIC. This gives you two advantages:
- increased bandwidth
- failover

Should one of the NICs fail, the driver will use the good one.

The only catch here is that you need a switch that supports it. It
called Trunking or Channel Bonding or WhatEverVendorsCallIt. Also, you
want a switch that supports Trunking *across* switches. Should one
switch fail, the other will still work. The only switch I've found
that supports it is the BayStack 450. BUT it only supports up to 6
configured trunks. I need 24. Oh well.

The Linux channel bonding code could be hacked to support a failover
only scenario.