Re: Comments/questions on Group A Section 2.7

From: Yong Jiang (yong.b.jiang@telia.se)
Date: Wed Mar 06 2002 - 11:58:36 EST


On Wed, 6 Mar 2002, Jeffrey Haas wrote:

> On Wed, Mar 06, 2002 at 11:43:38AM +0100, yong.b.jiang@telia.se wrote:
> > As far as forwarding behavior is concerned, routers need to know the right
> > NEXT HOP in order to forward packets correctly. This implies for a
> > customer connected to the Internet through a provider, it is enough for
> > its provider to converge since the customer will forward its packets to
> > its provider anyway, even though it still has wrong knowledge about the
> > global AS path.
>
> Just because you are using a route for forwarding doesn't mean that it
> will follow the AS_PATH of that route. The BGP mechanism to signal
Definitely. Since the real forwarding path doesn't follow the AS_PATH, the
forwarding behavior can be correct even if the router has wrong knowledge
about the AS_PATH of that route, which takes a longer time to converge.
This is because along this (wrong) AS path, somewhere there is an AS,
which is probably a provider, or a provider's provider, and this AS can converge
much earlier so that all its customers don't need to converge from the
forwarding's point of view.

My point is that we need to agree upon these different cases for
convergence, and define what is really we are after depending on what kind
of convergences we are talking about. Is it really necessary for all
routers within the whole Internet to get synchronized knowledge about the
right AS_PATH for each route?

/Yong
> that it might not (ATOMIC_AGGREGATE) isn't precise enought to give
> you warning that this may not be the case.

>
> > /Yong
>
> --
> Jeff Haas
> NextHop Technologies
>
>



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