From: Halaska, David (David.Halaska@xxxxxxxxxxxxx)
Date: Thu Feb 01 2001 - 18:44:45 GMT-3
You are correct in saying that you can use an as-path filter. You can also
use the community attribute. On the inbound interface of a EBGB peer, set
the community attribute to no export. Then you need to send the community
attribute to all IBGP peers because, by default, the community attribute is
not forwarded to a peer. Here's an example.
RTA(AS1)-----RTB(AS2)-----RTC(AS2)-----RTD(AS10)
In this scenario you want routes from AS1 to not pass through your AS and be
advertised to AS10. The configs would look like this: I've successfully
done this before, so I'm just typing it in. Forgive any errors since its
off the top of my head. You could also do a route-map denying
advertisements out to EBGP peer. Obviously this would be very tedious with
over 85k routes.
RTB
Router BGP 2
neighbor RTA remote-as 1
neighbor RTA route-map SETCOMMUNITY in
neighbor RTC remote-as 2
neighbor RTC send community
route-map SETCOMMUNITY permit 10
set community no-export
DO this the other direction to stop routes from AS10 getting to AS1.
So there are actually at least 3 ways I know about to do what you ask. Good
stuff to know for the lab, because they may say "make your AS a non-transist
AS but do not use such and such way to achieve it.
Hope this helps.
David Halaska
-----Original Message-----
From: Mike S. Lee [mailto:mikele@cisco.com]
Sent: Thursday, February 01, 2001 3:01 PM
To: ccielab@groupstudy.com
Subject: Non-transient AS's in BGP
Can any one please explain how to make an AS non-transient. I can do this
with an AS-Path ( ^$) but how would this be accomplished without using an
AS-Path filter. I have exhausted Halabi and just need to be pushed in the
right direction. Thanks for any help you can provide.
Mike Lee
CCNP+LATM+Security+Voice Access/CCDP
NNCSE/NNCDE
Cisco Systems, Inc.
12515 Research Blvd., Bldg. 04
Austin, TX 78759-2200
DSL Customer Support Engineering
mikele@cisco.com
(512)378-1331 ofc
Text Page: mikele@epage.cisco.com
Mike Lee
CCNP+LATM+Security+Voice Access/CCDP
NNCSE/NNCDE
Cisco Systems, Inc.
12515 Research Blvd., Bldg. 04
Austin, TX 78759-2200
DSL Customer Support Engineering
mikele@cisco.com
(512)378-1331 ofc
Text Page: mikele@epage.cisco.com
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