[c-nsp] Load balancing across 2 ADSL lines

[David Coulson]

James O'Farrell wrote:

> Thanks for that GLBP appears to be exactly what I am looking for. If the
> current gateway terminates VPN I assume GLBP will just balance between
> the 2 gateways irrelevant of the final destination and it is up to the
> gateway to deal with the VPN traffic.

Nope. GLBP is MAC-level load balancing. If the traffic comes from a
single MAC, then it will occasionally bounce between the two routers,
but won't actually be balanced. Like I said, GLBP only works well if you
have many hosts on a network, and they're roughly all pulling the same
amount of bandwidth.

If the DSL are to two different providers, then to do any sort of load
balancing, you're going to need a distinct end point somewhere
(preferably at one of the providers), where you can terminate some
tunnels and load balance over those using CEF or something. You may be
able to get away with using a couple of GRE tunnels into a cisco box
somewhere.

David