Communities

E.B. Dreger eddy+public+spam at noc.everquick.net
Mon Oct 15 17:26:54 UTC 2001


> Date: Mon, 15 Oct 2001 12:34:24 -0400
> From: Jeff Aitken <jaitken at aitken.com>

> How feasible is it for me to provide this information in any

[ snip ]

> This isn't to say that there isn't a reason to do this.  I can think

[ snip ]

> Without having a clear understanding of each upstream's network
> topology and routing policy, how would you use such information to
> label one route as "better" than another? 

Let's take a simple example.  Say that I connect to AS65123 in
DFW and AS65456 in Chicago.  Assume that both ASen have similar
peering with other networks.

Now, using only as-path length, where do I send traffic?  Is
as-path length the best metric?  No.  If I need traffic headed
for MSP, it should go through CHI.  If I need traffic to go to
Houston, it should be routed through Dallas.  How does one do
this now?  Static entries based on RADB or similar?!  If that's
acceptable, then why don't we just static route, period?!

Real example:

If I'm a 6347 downstream and I know that 6347 has transit via
701, 1239, 3561 near me, I'm going to use a route-map.  That's
easy.

Now let's take 3967... in most places, peering with 6347 seems
better than with 3549.  I send 3967 traffic via 6347.  But it's
not perfect... I'd rather send certain regions via 3549.  Without
regional tagging, how do I do that?  Hypothetical example made
into real example.

Furthermore, define "clear understanding".  If I test different
traffic paths, I can get a pretty clear understanding.  Not as
good as a detailed network map, but enough to tune routes better
than leaving them up to nature.

> What problem(s) are you trying to solve, and are you sure that 

See above.

> BGP communities are the right tool for the job?

Sure that they're the right tool, no.  Sure that they're the best
tool -- until someone shows me a better one.


Eddy

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Date: Mon, 21 May 2001 11:23:58 +0000 (GMT)
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