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BGP routing table is not showing all routes

I have a point-to-point connection between 5 cities and I am trying to run BGP between them.

Each city has these subnets associated with them

City 1 = 10.110.0.0

City 2 = 10.120.0.0

City 3 = 10.130.0.0

City 4 = 10.140.0.0

City 5 = 10.150.0.0

Router 1 is the main Point-to-Point router that has the connection to every router. If Router 2 wants to get to Router 4, it must go through Router 1.

On each router, i have a static route set for anything on that subnet to go back to the city's core router

for instance, Router 1 that has an ip address of 10.110.2.1 and has this static route.

ip route 10.110.0.0 255.255.0.0 10.110.2.2

the BGP configuration is like this on router 1

router bgp 64834

no synchronization

no auto-summary

network 10.110.0.0 mask 255.255.0.0

neighbor 10.120.2.1 remote-as 64834

neighbor 10.130.2.1 remote-as 64834

neighbor 10.140.2.1 remote-as 64834

neighbor 10.150.2.1 remote-as 64834

default-information originate

routers 2 through 5 have this type of configuration

router BGP 64834

no synchronization

no auto-summary

network 10.120.0.0 mask 255.255.0.0

neighbor 10.110.2.1 remote-as 64834

When i do a 'sh ip route' and a 'sh ip bgp' on Router 1 , it can see all the routes correctly.

When i do a 'sh ip route' on routers 2 through 5

it can only see its route and the route to router 1.

For instance.

a 'sh ip route' on router 2 can see its own network 10.120.0.0 and can see the neighbor routers network 10.110.0.0, but it cannot see router 3, 4 or 5s routes. It seems as if router 1 is not distributing the routes it receives from other cities.

Is there some type of configuration that I'm not setting up correctly?

TIA

2 REPLIES

Re: BGP routing table is not showing all routes

The problem is due to split horizon rule of BGP.

BGP does not forward an IBGP learned route to another IBGP peer by default. There are 2 ways to overcome this, either run a full mesh or use route-reflectors

On Router 1 add the following

router bgp 64834

neighbor 10.120.2.1 route-reflector-client

neighbor 10.130.2.1 route-reflector-client

neighbor 10.140.2.1 route-reflector-client

neighbor 10.150.2.1 route-reflector-client

Narayan

Community Member

Re: BGP routing table is not showing all routes

Narayan,

Thanks for the suggestion, I will try that tonight when I have time to take down the network.

I will report back with what I find.

Thanks!!

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