[c-nsp] BGP Upstream in different interfaces.

[Elmar K. Bins]

aaaa at telconet.net (Alexandra Alvarado) wrote:

> I would like to know if is possible to choose the upstream traffic by
> selected networks without applying "service policy" in the interface but by
> BGP in the neighbors?

Of course you can, it's your router and you can tell it what to do with
the route advertisements it sees. The key is as-path ACLs, and route-maps
with which you can set quite a lot of options based on the AS path the
prefixes carry (not based on the prefixes themselves, but that might not
be a good idea anyway).

Alas, this game's not easy, and from balancing four good transit ISPs, I
can tell you, balancing traffic evenly is out of the question anyway.
Even achieving what you think you'll achieve through $PREFER_THIS_FROM_HERE
is very hard and you're in for a couple of surprises.

Yours,
	Elmar.

PS: I recommend Bassam Halabi's "Internet Routing Architectures" for
    getting an advanced approach to BGP issues. Has helped me a lot,
    and not only with my _first_ steps. Get it directly from Cisco
    Press, since Amazon US seems to only carry the 1997 edition
    (Amazon DE has the 2000).

--

"Begehe nur nicht den Fehler, Meinung durch Sachverstand zu substituieren."
                          (PLemken, <bu6o7e$e6v0p$2 at ID-31.news.uni-berlin.de>)

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