Re: [LARTC] Balancing ip traffic over two or more internet (adsl)

[Arthur van Leeuwen <arthurvl@sci.kun.nl>]

On Thu, 15 Mar 2001, RoMaN SoFt / LLFB!! wrote:

>  I have set up a test machine to act as the "Linux IP Load balancer"
> and activated the "CONFIG_IP_ROUTE_MULTIPATH". Then I've set up two
> default routes with "ip route" and "equalize"-"nexthop" options. But
> it isn't working correctly. I think this method distribute packets in
> a round robin fashion but doesn't have the "session handling" problem
> into account, I fear.

Actually, the kernel does not necessarily send packets that already have
a source address out the interface associated with that address. That might
very well be your problem. The session problem does not really exist, as the
IP multipath code only multiplexes at the route-level. Once a route has been
set up it is entered into the route cache and will stay there, over the same
interfaces, for as long as packets are exchanged over it. Note that the
route-cache is keyed on the triple (src-address,dst-address,type-of-service).
The last part of that key may bite you with your 'session handling', as at
least one notable piece of client software, OpenSSH, changes the
type-of-service somewhere during the session. Fortunately, the TOS field
can be thwacked using ipchains or iptables so you can work around that...

Doei, Arthur. (Who hopes this is clearer than it looks...)

-- 
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