RE: BGP and Multipoint interface

From: Voss, David (dvoss@heidrick.com)
Date: Wed Mar 12 2003 - 23:12:04 GMT-3


My advice is not to focus on the underlying infrastructure when making your
BGP decisions. Focus on what next-hop-self really does and why you would
require it.

Your scenario shows 3 AS's on 3 routers. I can't see any reason why
next-hop-self would be required in the scenario you show below, although it
is a rather basic one with much interpritation to be done (peering, etc..)

Next-hop-self mainly buys you functionaility when dealing with routing
updates between 2 iBGP neighbors.

AS1-------------AS2---next-hop-self>-----AS2

If the router on the right does not know about the next-hop address of AS1,
it will not insert the routes advertised from AS1 in it's routing table.
This can be resolved by creating a next-hop-self statement from the middle
AS2 router to the AS2 router on the right. Now that the AS2 router on the
right knows of the next-hop, it will insert the routing update from AS1 in
it's routing table.

-----Original Message-----
From: Sanfilippo, Ted [mailto:Ted.Sanfilippo@PaeTec.com]
Sent: Wednesday, March 12, 2003 3:56 PM
To: 'ccielab@groupstudy.com'
Subject: BGP and Multipoint interface

Does anyone know of issues with the following set-up fro BGP on a Frame
Network:
 
 
 
                  AS2
                /
               /
AS1 --------
               \
                 \
                    AS3
 
All sites are on a frame relay network and AS1 is Multipoint and AS2 and AS3
are point-point to AS1.
 
Do I need to use Next-hop self on AS1?AS2?AS3?
 

Ted Sanfilippo
Manager of Backbone Network Engineering

PaeTec Communications
One PaeTec Plaza
600 Willowbrook Office Park
Fairport, NY 14450

Tel: 585-340-2722
Fax: 585-340-2786
Email: ted.sanfilippo@paetec.com



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