From: Jonathan V Hays (jhays@jtan.com)
Date: Sun Nov 16 2003 - 11:44:40 GMT-3
Silvio,
The LOCAL-AS attribute works in exactly the opposite manner: the route
can only be advertised to peers within the same sub-AS within a
confederation. The LOCAL-AS route will not be advertised to other AS's,
even if the other AS is in the same confederation. See the excerpt from
this link, included below.
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/
fipr_c/ipcprt2/1cfbgp.htm#1001855
The communities attribute is an optional, transitive, global attribute
in the numerical range from 1 to 4,294,967,200. Along with Internet
community, there are a few predefined, well-known communities, as
follows:
internet-Advertise this route to the Internet community. All routers
belong to it.
no-export-Do not advertise this route to eBGP peers.
no-advertise-Do not advertise this route to any peer (internal or
external).
LOCAL-AS-Do not advertise this route to peers outside the local
autonomous system. This route will not be advertised to other autonomous
systems or sub-autonomous systems when confederations are configured.
Based on
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On
>Behalf Of Silvio Nunes
>Sent: Sunday, November 16, 2003 9:24 AM
>To: ccielab@groupstudy.com
>Subject: MORE..BGP - Community attribute
>
>
>Regarding LOCAL-AS attribute, I4d like to confirm:
>
>A route with a LOCAL_AS attribute can be advertised to peers in other
>subautonomous systems within a confederation, but I4m trying
>and it is not
>working... the route cannot be advertised to another
>subautonomous systems..
>
>AS3 (R3)......[ AS10 (subAS5 -R5)----- (subAS5 - R2) ........
>(subAS6 - R6)]
>|
>|
>222.222.222.0
>
>In this example, R2 (in the same subAS) has 222.222.222.0. R6
>(in another
>subAS) cannot get the same route:
>
>(R5)
>router bgp 5
>bgp router-id 5.5.5.5
>bgp cluster-id 3368601605
>bgp log-neighbor-changes
>bgp confederation identifier 10
>bgp confederation peers 6
>neighbor 2.2.2.2 remote-as 5
>neighbor 2.2.2.2 ebgp-multihop 5
>neighbor 2.2.2.2 update-source Loopback0
>neighbor 2.2.2.2 send-community
>neighbor 2.2.2.2 route-map MODCOMMUNITY out
>neighbor 3.3.3.3 remote-as 3
>neighbor 3.3.3.3 ebgp-multihop 5
>neighbor 3.3.3.3 update-source Loopback0
>
>access-list 33 permit 222.222.222.0 0.0.0.255
>
>route-map MODCOMMUNITY permit 10
>match ip address 33
>set community local-as
>!
>
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