BGP route not learned

Routing & Switching BGP
1

Hi I have a quick question I was checking my BGP config to see why my peer router wasn’t learning a particular route. On my router I can see that I am advertising it and that the route is valid and active

se7wancsw20140ha2#sh ip bgp neigh 10.125.7.22 adver
BGP routing table information for VRF default
Router identifier 172.17.7.2, local AS number 65470
Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
                    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
Origin codes: i - IGP, e - EGP, ? - incomplete
AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop

         Network                Next Hop            Metric  LocPref Weight  Path
 * >     162.68.200.0/25        10.125.7.21           -       -       -       65470 65480 ?
 * >     162.68.200.128/25      10.125.7.21           -       -       -       65470 65480 ?

When I go to the peer router and double check all the routes that I am receiving I do not see it.

se7dcicsw10442at#sh ip bgp neigh 10.250.7.21 received-routes 
BGP routing table information for VRF default
Router identifier 172.17.7.3, local AS number 65480
Route status codes: s - suppressed, * - valid, > - active, # - not installed, E - ECMP head, e - ECMP
                    S - Stale, c - Contributing to ECMP, b - backup, L - labeled-unicast
Origin codes: i - IGP, e - EGP, ? - incomplete
AS Path Attributes: Or-ID - Originator ID, C-LST - Cluster List, LL Nexthop - Link Local Nexthop

         Network                Next Hop            Metric  LocPref Weight  Path
 * >     162.68.176.0/22        10.125.7.21           -       -       -       65470 i
 * >     162.68.180.0/22        10.125.7.21           -       -       -       65470 i
 *       162.68.233.0/25        10.125.7.21           -       -       -       65470 ?

I checked for access-list on both routers and the only one I see an access-list for is my router se7wancsw20140ha2. The peer router, se7dcicsw10442at, has none. So I am thinking the reason why that is is because both peer are configured for

neighbor SE-755-201-7150S-WAN maximum-routes 12000
neighbor SE-755-201-7150S-TCWANB maximum-routes 12000

and I am reaching the max route that is why the route for
162.68.200.0/25
162.68.200.128/25
isn’t installed in the peer router se7dcicsw10442at. Is my assumption correct and if so how do I verify that?

Thank you

Warren

2

Hello Warren

There are several reasons why a BGP route may not be installed on a BGP router. This could be due to a route-map blocking specific routes from being shared, an unreachable next hop IP, or iBGP split horizon to name a few. Take a look at the following two lessons that will help you to troubleshoot the specific situation:

It is unlikely that the maximum-routes command is blocking the installation of the routes. I suggest you also examine the state of the BGP peering between the two routers to ensure it is up and running.

Let us know how you get along and if we can be of any further help.

I hope this has been helpful!

Laz

3

Yes I check for a route map but let me double check again perhaps I am blind, will let you know.

Thank you!!

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