From: Maneesh Chawla (coolmaneesh@gmail.com)
Date: Wed Jan 04 2006 - 07:52:41 GMT-3
To me,it looks like more of a bug in the box.
On 1/4/06, easyman <easyman@primetek.com.tw> wrote:
>
> Yes, I have the same doubt.
> It become a habit to use "neighbor send-community" if I configured any of
> the communities(well-known or not).
> But in definition, COMMUNITY is an "Optional transitive" attribute.
>
> From Doylye's books,
> If an optional attribute is transitive, a BGP process should accept the
> path
> in which it is included, even if it doesn't support the attribute, and it
> should pass the path on to its peers.
>
> Can we extended the definition to "a BGP process should accept the
> attribute
> in which
> ^^^^^^^^
> it is included, even if it doesn't support the attribute, and it should
> pass
> the attribute
> ^^^^^^^
> with the path on to its peers".
>
> Comments are appreciated
> Regards
> Lin
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Schulz, Dave
> Sent: Wednesday, January 04, 2006 1:39 AM
> To: Cisco certification
> Subject: Local-as and no-export community issue
>
> Here is an interesting problem that I ran into in the lab....and, can't
> seem to find the solution. I have 3 AS's in BGP and want to use the
> local AS option with communities....
>
> I have R4 as AS400....sending to R1 (AS155/local-as100)....connected to
> R3 in the same AS.....
>
> R4(AS400)---------------------------R1(AS 155 (local-as100)
> ------------------R3 (AS155(localAS155)
>
> All adjacencies form and everything is operating correctly, except....
> The networks that I am sending from R4 to R1 get sent with the community
> of "no-export".....the routes come through, but the R3 router does not
> maintain the "no export" attributes. I know that this works without the
> local-as options, but can't understand why this would make any
> difference in this scenario. Also, I can fix the issue by configuring
> the neighbor statement with the send-community option on R1, pointing to
> R3 (everything is working)....of course, this allows the community
> option to be passed....however, I wouldn't think that I would have to do
> that, since the community option should be controlled from R4, otherwise
> a remote provider/customer can override your intentions to not allow
> them to become a transit AS. Thoughts?
>
>
> Here are the configs for R4 and R1.....
>
> R4.......
> interface Loopback10
> ip address 41.4.4.4 255.255.255.0 secondary
> ip address 42.4.4.4 255.255.255.0 secondary
> ip address 43.4.4.4 255.255.255.0 secondary
> ip address 44.4.4.4 255.255.255.0 secondary
> ip address 45.4.4.4 255.255.255.0 secondary
> ip address 40.4.4.4 255.255.255.0
> !
> interface Loopback104
> ip address 172.16.104.1 255.255.255.0
> !
> interface Serial0
> ip address 172.16.14.4 255.255.255.0
> !
> router bgp 400
> no synchronization
> bgp log-neighbor-changes
> network 40.4.4.0 mask 255.255.255.0
> network 41.4.4.0 mask 255.255.255.0
> network 42.4.4.0 mask 255.255.255.0
> network 43.4.4.0 mask 255.255.255.0
> network 44.4.4.0 mask 255.255.255.0
> network 45.4.4.0 mask 255.255.255.0
> neighbor 172.16.14.1 remote-as 100
> neighbor 172.16.14.1 send-community
> neighbor 172.16.14.1 route-map COMM out
> no auto-summary
> !
> !
> access-list 1 permit 40.4.4.0 0.0.0.255
> access-list 1 permit 41.4.4.0 0.0.0.255
> !
> route-map COMM permit 10
> match ip address 1
> set community no-export
> !
>
>
> R1.....
> interface Serial0.14 point-to-point
> ip address 172.16.14.1 255.255.255.0
> !
> interface Serial0.123 multipoint
> ip address 172.16.123.1 255.255.255.0
> !
> router bgp 155
> no synchronization
> bgp log-neighbor-changes
> neighbor 172.16.14.4 remote-as 400
> neighbor 172.16.14.4 local-as 100
> neighbor 172.16.123.3 remote-as 155
> no auto-summary
> !
> access-list 1 permit 225.5.5.5
> !
> route-map COMM permit 10
> set community no-export
> !
>
> Routes..........
>
> R3#sh ip bgp 40.4.4.0
> BGP routing table entry for 40.4.4.0/24, version 6
> Paths: (1 available, best #1, table Default-IP-Routing-Table)
> Advertised to non peer-group peers:
> 10.1.1.6
> 100 400
> 172.16.14.4 (metric 128) from 172.16.123.1 (172.16.101.1)
> Origin IGP, metric 0, localpref 100, valid, internal, best
>
> R1#sh ip bgp 40.4.4.0
> BGP routing table entry for 40.4.4.0/24, version 2
> Paths: (1 available, best #1, table Default-IP-Routing-Table, not
> advertised to EBGP peer)
> Advertised to non peer-group peers:
> 172.16.123.3
> 100 400
> 172.16.14.4 from 172.16.14.4 (172.16.104.1)
> Origin IGP, metric 0, localpref 100, valid, external, best
> Community: no-export
>
>
> Dave Schulz,
> Email: dschulz@dpsciences.com <mailto:dschulz@dpsciences.com >
>
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