From: David T. Absalom (dabsalom@xxxxxxxxxx)
Date: Fri Mar 02 2001 - 12:17:26 GMT-3
I believe you could use a outgoing route map for the ebgp sessions on r1 and
r2 to only allow local routes be advertised, i.e.
ip as-patch access-list 1 permit ^$
route-map notransit permit 10
match as-path 1
This would only allow routes from AS1100 to be advertised via ebgp.
Hope this helps...
dave
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]On Behalf Of
Mark Salmon
Sent: Friday, March 02, 2001 9:42 AM
To: ccielab@groupstudy.com
Subject: BGP problem
I have a BGP issue I want to bring to the group.
as500 --------ebgp------as600
| |
| |
ebgp ebgp
| |
| |
r1:as1100--------ibgp-----r2:as1100
I need r1 to use as500 exclusively as its exit and entrance as well as
r2 must use as600 exclusively as its entrance and exit. However, if the
links between r1 and as500 is lost, it must reroute through r2 to
as600. The same applies to r2. No load balancing is necessary. That
is not the problem, I am OK with setting up local preferences etc.
The problem is, I do not want as1100 to be a transit as for Internet
routes.
My idea is to use community lists and no export option from r1 to as500
as well as r2 to as600. I used ip as-path access lists and that is
where the problem starts. I do not see the as1100 routes on as500 or
as600 routers
Here is my config on one router (it is virtually identical on the other
router):
. router bgp 1100
network 192.168.1.0
network 192.168.3.0
neighbor 192.168.2.2 remote-as 1100
neighbor 192.168.25.2 remote-as 500
neighbor 192.168.25.2 send-community
neighbor 192.168.25.2 route-map nointernet out
!
ip classless
ip as-path access-list 1 permit _1100_
route-map nointernet permit 10
match as-path 1
set community no-export
--Mark Salmon Network Support Engineer - SBC OP HQ Cisco Systems Inc 8735 W. Higgins Road Suite 300 Chicago IL 60631 Phone:773-695-8235 Pager:800-365-4578 email: masalmon@cisco.com Empowering The Internet Generation.
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