Distributing load over multiple links

From: <andrew@dont-contact.us>
Date: Mon, 6 Oct 1997 21:08:16 +1100 (EST)


I will have a situation in a few days where a network is conencted to the
Internet via 2 links, a 128K ISDN and a 2MB link. The 2MB link goes to a
provider very distant (network wise) from the provider the ISDN goes to.

I dont want to run BGP if I can help it due to lack of memory in routers
and as most traffic is web I thought I would just play with the routing of
squid traffic.

Bad Picture of Network Setup:

  Network A <-- 128K --> Squid <-- 2Mb --> Network B <--large--> Internet
         | |
         \_________Some unknown link___________________________________/

Now the 2Mb link is charged by the MB, the ISDN is charged flat rate
(while utilisation is under 40%). We have a parent cache on Net B.

What I thought should happen would be...

Squid box will have a static route telling it to get to the parent on Net
B via 2Mb link.

All squid traffic comes in via ISDN direct from source. If ping times up
ISDN become greater than x then a script swaps squid.conf and HUPs squid.

Squid then fetches all data from network A and y% of all other traffic
direcxt from source (and therefore via ISDN). All remaining traffic (bulk
of traffic) goes to squid parent on Network B and therfore via 2Mb link.
The figure y will be detrmined by trial and error...ie what creates
acceptable delay for non web traffic but costs us least.

The question is...How to I load balance between source and a parent? I
know how to do it btween multiple parents...do I just create a non
cacheing proxy server on the same box as squid and configure it as a

Perhaps the question really is...is this a really stupid thing to do? Any
better ideas?

Received on Mon Oct 06 1997 - 03:10:47 MDT

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