04-24-2015 03:14 PM - edited 03-05-2019 01:19 AM
I am having issues with BGP seeing the advertised routes. I am trying to find an alternate to AS-Path prepend and trying to use bgp instead for a redundant path.
Setup:-
We have 3 mpls sites. (in reality its more than 20 but for simplicity we will call that 3). The 3 sites are SiteA , SiteB and siteC. I have simplified the issue below.
SiteA - Has MPLS link running eBGP with AS 300.
SiteB - Has MPLS link running eBGP with AS 200
SiteC- Has MPLS link running eBGP with AS 100
Site B and C has a local LAN connection between each other. Site A and B and C are on BGP network. Site A can see B and C and so on.
Issue:
I have established eBGP neighbor relationship between B and C using multihop using the private link between two private interface ip address. I can see them as neighbors.
When i advertise the network of site B at site C i see that in the advertised routes on site C when i run sh ip bgp nei x.x.x.x advertised-routes but i don't see that at site A when i run "show ip bgp"
From Site A:
When i run show ip bgp : I was expecting to see...
20.20.20.20 - is reachable as As200 -i
Also..
20.20.20.20 - As100 - 200 - i (i don't see this)
That way it will be a backup path instead of using as-path prepend.
Can you throw some ldeas as to what i am missing. If i am not clear enough let me know and i will provide more details.
04-25-2015 04:16 AM
Hello
when you say "advertise network from site B at site C"
how are you doing this.?
For a route to be advertised in bgp it's need to be in the rib of the advertising router
so if you have just applied a network statement (bgp table) for site B at site C and site C route doesn't have a valid prefix in its routing table it won't get advertised to site A
Site C router
Sh ip route x.x.x.x
sh ip bgp x.x.x.x
res
Paul
04-25-2015 05:57 PM
Thanks for responding. i have added a prefix list for filtering outbound. I was hoping that it will learn that route through the bgp network statement.
ie.. I have added network B at C and network C at B. They both are neighbors and when i see advertised routes and received routes i can see the routes.
How should i proceed or any guidance would help..
From site C i want to see below when i do show ip bgp for 20.20.20.20.
20.20.20.20 - is reachable as As200 -i
20.20.20.20 - As100 - 200 - i (i don't see this)
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