Subject: Multiple BGP Process

From: Mareline Sheldon <[email-masked]>
Date: Thu, 19 Sep 2002 00:14:24 -0700 (PDT)

Hi,
Do we have this concept of running multiple BGP processes on a signle router? I could not find
any literature on the net and will appreciate if anybody could give me some pointers to it. Is
there any need for that?

Thanks,
mareline s.

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From: Curtis Villamizar <[email-masked]>
Date: Fri, 20 Sep 2002 13:31:46 -0400

In message <[email-masked]>, Mareline Sheld
> any literature on the net and will appreciate if anybody could give me some p

Not a big deal.

In cases where it is useful to have one router appear to be in two
different AS, for example doing IBGP in both, two BGP processes are
run rather than buying two routers and a link between them.

This seems to happen at the US/Europe boundary for one ISP where due
to traffic engineering requirements of the interconnect points the
same router could benefit from having traffic engineering information
from both AS.

Partition of the IGP is desirable for scaling.  IGP areas would solve
this but IGP areas are already used in US and in Europe so two AS are
used.  I think these are internal AS and so are not visible to the
outside world.

The only thing that might be non-obvious is that it is desirable to
have policy control and aggregation of information between the BGP
processes.

This is just one example.  There are others.

Curtis

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From: Mareline Sheldon <[email-masked]>
Date: Mon, 23 Sep 2002 01:40:28 -0700 (PDT)

Curtis,
> run rather than buying two routers and a link between them.
Not necessarily .. you dont need to run two BGP processes to make one router appear to be in
two different AS as IBGP in both. You can have the same instance/process running and still do
that using different views.

regards,
marelines s.

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From: Curtis Villamizar <[email-masked]>
Date: Mon, 23 Sep 2002 08:55:21 -0400

In message <[email-masked]>, Mareline Sheld
> that using different views.

Views, gated tasks, threads, processes ... we're talking
implementation details here.  Gated is proof that you can run all of
your protocols without the help of threads, or processes and without
the help of the scheduler provided by the OS.

The point is the the two instances of BGP, however they are
implemented and whatever you'd like to call them, have different
loc-RIBs and it is desirable to provide the ability to specify policy
to export or aggregate between them.  There is an issue of which
loc-RIB (or what combination of them) gets installed in the FIB or
whether there are also two FIBs with the appropriate one installed on
interfaces facing each AS.

We're well outside the scope of the BGP spec.

Curtis