Re: BGP configuration problem

julxu · ‎10-27-2010

Greeting

I have a bgp router, and it has more than one connections. they looks all can send whole routing table to the neibour without problem. However, I have just configure a new one with private ip address 10.10.10.248/30. the porpose is to send a class B address route to another end.

unfortunately, I have no any route-map and prefix list, but it only advice the default route 0.0.0.0 out, not public addrese route.

the configuration just simple at:

another end (the related configure)

router bgp 64500

no synchronization

bgp log-neighbor-changes

neighbor 10.10.10.249 remote-as 64500

neighbor 10.10.10.249 next-hop-self

neighbor 10.10.10.249 soft-reconfiguration inbound

no auto-summary

my end (the related configure)

route bgp 64500

no synchronization

bgp log-neighbor-changes

bgp bestpath med missing-as-worst

network 10.10.10.248 mask 255.255.255.252

neighbor 10.10.10.250 remote-as 64500

neighbor 10.10.10.250 transport path-mtu-discovery

neighbor 10.10.10.250 next-hop-self

neighbor 10.10.10.250 soft-reconfiguration inbound

if I do ip bgp neighbor 10.10.10.250 advertised-routes, it give me only 0.0.0.0 and 10.10.10.248. the rest routes all can not be advertised.

It realy confuses me. I have a list of public addresses, but, for some reason they can no be send to another end without no reason.

Any comments will be appreciated

Thanks in advance

julxu

Atif Awan · ‎10-27-2010

I see that you have an iBGP connection with this neighbor. Are the BGP routes that should be advertised to this new neighbor learnt from other iBGP neighbors?

Atif

julxu · ‎10-27-2010

Atif

great thanks for your reply.

yes, you are right, it is learned from other ibgp router. basically, I want private 10.0.0.0/8 and my public address route to pass to another router. not default 0.0.0.0.

is it possible?

julxu

Atif Awan · ‎10-27-2010

julxu wrote:
Atif
great thanks for your reply.
yes, you are right, it is learned from other ibgp router. basically, I want private 10.0.0.0/8 and my public address route to pass to another router. not default 0.0.0.0.
is it possible?
julxu

You need to understand that a BGP speaker will not advertise any route it learnt from an iBGP neighbor to another iBGP neighbor. This is as per design and is done to prevent loops. Proper way of addressing this is to have a full iBGP mesh or use scaling approaches like route reflectors / confeds. If this is the behavior you are seeing then this is normal and you need to consider that in your BGP design. If there is additional complexity to what you are seeing then please elaborate the problem and provide as much detail as possible so someone can assist you.

Atif