Multipul ppp connections to different isp's

Brian Somers brian at
Sat May 6 00:47:52 BST 2000

See share/examples/ppp/*span-isp*.  The only problem is that you need 
access to a machine on the outside to re-join the multi-link session.

> Ian MacDonald wrote:
> > 
> > Is it possible to "load balance" across 2 or more modems to different isp's
> > (e.g. freeserve, freenetname etc). I have had a look pack trough past FBSD
> > mailing lists but the only things I could find were use ospf (not likely) or
> > use mpd (which does not support multiple peers).
> > 
> > What I can do is dial up both isp's and change the default route by hand and
> > it will change the route the packets take. The only problem is that if the
> > packets go out on one connection (quite rightly) they must come pack in on
> > that connection. This is fine for ping and stateless connections but will
> > not ahndle ftp etc.
> > 
> > Has anyone got any ideas on this.
> The problem is that the source IP address of packets passing over each
> ISP is different. So a given TCP connection *must* use the same ISP
> thoughout the entire session. If you want to load balance across
> multiple ISPs you either need to add static routes or have a hoopy NAT
> layer that handles multiple routes.
> Richard.

Brian <brian at>                        <brian@[uk.]>
      <>                   <brian@[uk.]>
Don't _EVER_ lose your sense of humour !

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