From: Nigel Taylor (nigel_taylor@xxxxxxxxxxx)
Date: Sun Feb 25 2001 - 21:35:38 GMT-3
Dan,
I understand the fatkid solution to flag the inbound routing
information as it enters AS200. I don't have a problem with this at all.
My question was on the need for the various "neighbor <neighbor-address>
send-community" on all of the bgp peers within AS200. This command enables
the use of the community attribute but you also need a route-map to pass the
"no-export" variable. In the fatkid solution all the neighbor peers on R2,
R3, and R4 have
"neighbor <neighbor-address> send-community" on them so I was trying to
figure out the purpose for this.
Compared to the configuration I came up with, I applied the above noted
configuration to R2 and R3(outbound) pointing to R4. I didn't see the need
for the extra commands on R4 to the route-rreflector-clients
I know there's a number of ways to achieve specific goals but I was just
trying to get an overall understanding of the solution provided looking at
requirements to a lab or using best design/configuration practices. My
thinking suggest that since task 11 asked for the routes from AS300 not to
be exported to AS100, then the emphasis on filtering these inbound routes
shouldn't be of major concern. As long as the both entry points apply the
outward "no-export" community attribute then there is really no way R4 would
pass the external (AS300)routes to AS100. Another key reason I'm thinking
is the use of the bgp router-id providing a IGP routable path to all BGP
peers.
I included a paste of my final relevant configs... compared to the fatkid
solution...
thoughts.
Nigel..
R2:
router bgp 200
bgp router-id 190.19.15.145
redistribute eigrp 200 route-map localnet
neighbor 190.19.15.177 remote-as 200
neighbor 190.19.15.177 update-source Loopback0
neighbor 190.19.15.177 send-community
neighbor 190.19.15.177 route-map setcom out
neighbor 210.10.10.5 remote-as 300
neighbor 210.10.10.5 weight 450
no auto-summary
!
ip classless
!
dialer-list 1 protocol ip permit
route-map setcom permit 10
set community no-export
R3:
router bgp 200
bgp router-id 190.19.15.161
redistribute eigrp 200 route-map localnet
neighbor 190.19.15.177 remote-as 200
neighbor 190.19.15.177 update-source Loopback0
neighbor 190.19.15.177 send-community
neighbor 190.19.15.177 route-map setcom out
neighbor 210.10.10.1 remote-as 300
no auto-summary
!
ip classless
!
dialer-list 1 protocol ip permit
route-map setcom permit 10
set community no-export
R4:
router bgp 200
bgp router-id 190.19.15.177
bgp log-neighbor-changes
redistribute eigrp 200 route-map localnet
neighbor 190.19.15.145 remote-as 200
neighbor 190.19.15.145 update-source Loopback0
neighbor 190.19.15.145 route-reflector-client
neighbor 190.19.15.161 remote-as 200
neighbor 190.19.15.161 update-source Loopback0
neighbor 190.19.15.161 route-reflector-client
neighbor 192.19.15.1 remote-as 100
neighbor 192.19.15.1 route-map weight250 in
no auto-summary
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