RE: BGP and Multipoint interface

From: Brian Dennis (brian@labforge.com)
Date: Thu Mar 13 2003 - 00:06:22 GMT-3


Since the subinterfaces on AS2 and AS3 are point-to-point you won't have
an issue with the next hop because spoke can reach spoke.

With this being a multi-access network, AS1 will not alter the next hop
address for updates about AS2 sent to AS3 and vice versa. This could be
a potential problem for the spokes reaching the next hop address with
physical interfaces or multipoint subinterfaces if there aren't any
frame-relay mappings from spoke to spoke. Of course there are a few ways
to solve this:

1) Use "next-hop-self" on AS1.
2) Frame-relay mappings from spoke to spoke.
3) Static /32 routes.
4) Policy routing (not pretty but will work).
5) OSPF point-to-multipoint network between AS1, AS2 and AS3. (Not
likely in the real world).

Brian Dennis, CCIE #2210 (R&S/ISP Dial/Security) CCSI# 98640
brian@labforge.com
 

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Sanfilippo, Ted
Sent: Wednesday, March 12, 2003 1:56 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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