Full Version: BGP Question NF78 ip route command (typo - please read)
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I don't understand why installing a static route to would help RouterA advertise prefix and if RouterA is running OSPF why wouldn't it have in its routing table already anyway?

AS 65500 is not advertising prefix to its provider. AS 65500 is running OSPF as its IGP. Which of the following additions to the config is most likely to solve the problem?

Correct Answer: RouterA(config)#ip route null0

Thanks, Gary


BGP is very picky when it comes to taking network statements and advertising them.  The network statement must EXACTLY match the routes as they appear in the routing table propagated by the IGP (unless synchronization is turned off).  Perhaps Router B is not advertising a summary route but many different singular routes within the range of,  If this is the case then you would either need network statements for each one or you would need to create a summary on Router A.

We already have a network statement which should inject a route into BGP and advertise it out to the neighbor if it can be found in the routing table propagated by an IGP or a static route.  That is why this is the correct answer.  Without seeing the routing table I can't tell you why the OSPF routes are not being picked up by BGP but its most likely because Router B is not sending them as a summary but instead individual subnets within that range.  If that were true and you didn't want to create the static summary route then you would have to create network statements for each subnet as it appears in the routing table propagated by OSPF.


Thanks for your reply.  Understood about the picky network statement part.  I hadn't thought about the possibility of RouterA receiving a different prefix from RouterB.  Duh, on my part.

I'll assume though that the ip route null0 command is a typo then and should read ip route null0 since we are attempting to advertise not


Yes for sure that is a typo.  You may want to change the subject of the topic to "typo please correct: BGP Question NF78 ip route command" so that it will get the attention of the forum Admin.