North American Network Operators Group

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Re: BGP - weight

  • From: E.B. Dreger
  • Date: Sat Feb 14 23:51:10 2004

SH> Date: Sat, 14 Feb 2004 18:00:51 +0000
SH> From: Sven Huster

SH> The thing that happend was that the core believed that the
SH> best path out is via R1, which R1 thought it was via R2. So a
SH> little loop there.

So core sends to R1, which sends to R2... where does R2 send the
packets?  Back to R1?

What are you doing in your IGP?  Are you using { iBGP | OSPF |
IS-IS | ... }?  How does R1 learn routes from Transit2?

What about confederations?  Used correctly, they're helpful.
Used incorrectly in similar scenarios, an iBGP mesh becomes a
constantly-oscillating iBGP mess.

Are you using either

	router bgp xxxx
	 bgp bestpath compare-routerid


	router bgp xxxx
	 no bgp bestpath compare-routerid

on all routers?  I'm wondering if R1 prefers Transit2 and R2
prefers Transit1 due to different path selection algorithms...

Can you "sh route" or "sh ip bgp" for a route that loops?

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