Routing question -- multiple gateway setup?

[Robert Brockway]

On Sun, 22 Aug 2004, James Knott wrote:

> Are your links with the same ISP?  I thought load balancing had to be
> configured at both ends.

Depends on how the load balancing is done.  With MLPPP both physical links
appear to be one logical link so support is needed at both ends, but with
iproute2 the packets are sent out one link and then the other in turn.

It would be like you were sitting there and toggling the default route
really fast.

Iproute2 actually allows for weighting so you could send packets out 2:1
in favour of a faster link for example.

As mentioned, when this is done on the same box as NAT (last time I
checked) it falls flat.  The kernel doesn't seem to be able to conn_track
them properly and as a result it drops some returning packets in this
situation :(

I will trial it again when I get time as the dual links have proven useful
(originally it was meant only as a transition but the costs were low
enough I kept it :)

Right now my route monitoring script deals quite well with the situation
by manually shifting the default route if the primary link drops.  HTTP
traffic is already designated to go out over the secondary by way of
a proxy-cache.

Rob

-- 
Robert Brockway B.Sc. email: robert-5LEc/6Zm6xCUd8a0hrldnti2O/JbrIOy at public.gmane.org, rbrockway-cFo9iiqjkw8eIZ0/mPfg9Q at public.gmane.org
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