| cyscoguru 2002-07-30, 3:33 pm |
| ok you ccie junkies out there i have a problem. please help.
http://www.cisco.com/univercd/cc/td...gp.htm#xtocid10
please click on that link and click on Community Attribute link. look at figure 39-7. i am doing a lab that is similiar to that. my task is to:
1. anything originating from AS1 should not propagate past AS2.
ok so i have to use the community attribute no-export. easy as that. well here it is. Router B see's the 172.16.1.0/24 network with a community attribute of no-export if i do a sh ip bgp 172.16.1.0 on router C it don't see a community attribute. it don't even see the community attribute that is supposedly to be attached to 172.16.1.0/24.
ok so here is sh ip bgp output for the ex:
on my r4 (routerb in the example):
BGP routing table entry for 196.1.1.0/24, version 39
Paths: (1 available, best #1, table Default-IP-Routing-Table, not advertised to EBGP peer)
Advertised to non peer-group peers:
145.1.63.3
999
145.1.14.1 from 145.1.14.1 (196.1.1.1)
Origin IGP, metric 0, localpref 100, valid, external, best
Community: no-export
on my r3 (routerc in the example):
BGP routing table entry for 196.1.1.0/24, version 40
Paths: (1 available, best #1, table Default-IP-Routing-Table)
Not advertised to any peer
999
145.1.14.1 (metric 20) from 145.1.111.4 (145.1.4.4)
Origin IGP, metric 0, localpref 100, valid, internal, best
on my r4 and r3 example are iBGP peers. as you can see by default iBGP routes are a localpref of 100. but what is not happening is r4 is not attachting the no-export community when its being sent to any iBGPs. R3 is also a stub router for the AS. so it only has a iBGP connection to R4. and R4 is connected to my R1 via eBGP. and R1 setting the community attribute on the 196.1.1.0/24 network.
i have read many examples of no ex-port. and as far as i am understanding you only have to set the community attribute on one router. for me to get the community to get attached to the route i have to put a nieghbor [ip-ad] send-community on r4. but the community is set on an different AS.
i tried to make this as detailed as possible. i am running ios ver 12.1(12b). and has anybody run into this problem.
Thanks in advance. |