Re: BGP community attribute

From: Kevin Baumgartner (kbaumgar@xxxxxxxxx)
Date: Fri Sep 29 2000 - 00:17:16 GMT-3


   
>
> Watch out! You've just given a definition of the 'no-advertise' community
> attribute.
>
> No-export - don't advertise to eBGP neighbors. (This route will not go
> outside the AS).

 Well you are wrong. (at least partly)

 Just tried the following

 R1 R2 R3
 AS 1 ----------- AS 2-------- AS 3

 So start with the following R1 configuration

router bgp 1
 bgp log-neighbor-changes
 network 10.1.1.0 mask 255.255.255.0
 neighbor 192.168.1.2 remote-as 2

 So just redistributing 10.1.1.0 network into BGP
to R2 and R3. Now see the route on R2 and R3.

 Now change R1 configuration to do community no-export
on 10.1.1.0.

 router bgp 1
 bgp log-neighbor-changes
 network 10.1.1.0 mask 255.255.255.0
 neighbor 192.168.1.2 remote-as 2
 neighbor 192.168.1.2 send-community
 neighbor 192.168.1.2 route-map no-export out
access-list 1 permit 10.1.1.0 0.0.0.255
route-map no-export permit 10
 match ip address 1
 set community no-export

 Now after do clear ip bgp * on all routers and once
BGP is stable only now see the 10.1.1.0 network on R1
and R2. Don't see on R3.

 What defining "community no-export" is to tag this
route so that it will not be sent out R2.

 Kevin



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