BGP Conditional Route Injection doesn't work, need help.

Answered Question
Aug 3rd, 2007
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Hi, forum


Based on the following link:


http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guide09186a008056c866.html


I was doing a lab test for this new feature. The lab senario is very simple, R1 send 10.1.1.0/24 to R2, R2 will conditional injects 10.1.1.0/25 and 10.1.1.128/25 to the BGP table. Unfortunately, I failed to make this happen. Below is the show ip bgp command output:


r2#sh ip bgp 10.1.1.0

BGP routing table entry for 10.1.1.0/24, version 2

Paths: (1 available, best #1, table Default-IP-Routing-Table)

Not advertised to any peer

100

10.0.0.1 from 10.0.0.1 (10.2.1.1)

Origin IGP, metric 0, localpref 100, valid, external, best

r2#

r2#

r2#

r2#sh ip bgp inj

r2#sh ip bgp injected-paths


r2#


As you can see, there is no routes to be injected which should be there. I 've tried it over and over but no luck. Could anybody help me figure out this issue. What have I missed?


Attached is the configuration of r1 and r2.


Thanks for your helps.


SSLIN






Attachment: 
Correct Answer by Harold Ritter about 9 years 9 months ago

SSLIN,


The issue is with the ROUTE_SOURCE prefix-list. You are matching against the BGP RID, when the route source should be the BGP next hop (10.0.0.1). Just change the prefix-list and it should work.


Hope this helps,

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royalblues Sat, 08/04/2007 - 04:58
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Can you post the output of sh ip bgp on R2 & R1


Narayan

CSCO10892433 Tue, 08/07/2007 - 04:42
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Hi, Narayan


Thanks for your reply.Problem has been solved by using Harold's method. If you are still interering in seeing the show ip bgp output, please let me know.


Best Regards

SSLIN

Correct Answer
Harold Ritter Sat, 08/04/2007 - 07:25
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SSLIN,


The issue is with the ROUTE_SOURCE prefix-list. You are matching against the BGP RID, when the route source should be the BGP next hop (10.0.0.1). Just change the prefix-list and it should work.


Hope this helps,

CSCO10892433 Tue, 08/07/2007 - 04:32
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Hi, Narayan,HAROLD,Pavlo


Thanks for all the replies to my question. Problem have been solved by using Harold's method. Besides that,I have to add another peer to R2 so that the injeted routes have a way to advertise out.


Harold, do you agree that the link

http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guide09186a008056c866.html

is kind of misleading? It's the link says using 10.1.2.1/32 for route source and it looks just like a loopback address to me. And also, if there is a diagram on this link, it would be easier for us to correctly set up a lab senario and quickly verified this BGP feature. Thanks for you help.


Best Regards

SSLIN

Harold Ritter Tue, 08/07/2007 - 05:24
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SSLIN,


I agree that the example provided in this document is not very clear. I will work with the documentation team to rectify this situation.


Thanks for the comment,

Pavel Bykov Mon, 08/06/2007 - 10:18
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I agree with Harold.

Also, i had bad experience using PREFIX lists to match route-source. Try using standard ACL instead.

like:

access-list 10 permit host 10.0.0.1

route-map LEARNED_PATH permit 10

no match ip route-source

match ip route-source 10

CSCO10892433 Tue, 08/07/2007 - 04:39
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Hi, pavlo


Thanks for your interesting suggestion, but prefix-list is not an issues for this case.


Thank you

SSLIN

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