BGP routing in multi-homed

[gryffindor]

Hi,

I have two BGPs configured on my core router. One is with P2P link to another location (site B). Other is with MPLS circuit which connects all other sites. Now, my routes from site B are being learnt from P2P bgp while of other sites from MPLS. This seems to be a correct solution. 

I am being new here, couldn't understand how this is implemented. Could you please share some inputs which I could use to identify the routing implemented or if I could check the routes from site B through both BGPs. I tried show ip routes bgp to check if a route from site B is being learnt from MPLS but I guess, it is only showing the best/selected routes.

Thank You

[balaji.bandi · Accepted solution]

Is both the links terminated to the same Router or a different router?

One of the Good features of the BGP is Loop prevention, it automatically detects and not announce the routes back. so it prevents the loop.

yes it only selects the best path based on the BGP calculations. but you can do Traffic engineering if you like what Link to be preferred or you can do asymmetric routing however you like. (there is limitation if any FW involved), if this is directly connected you can do.

show ip bgp

To display entries in the Border Gateway Protocol (BGP) routing table, use the show ip bgp command in user EXEC or privileged EXEC mode.

show ip bgp [ip-address [mask [longer-prefixes [injected] | shorter-prefixes [length] | bestpath | multipaths | subnets] | bestpath | multipaths] | all | oer-paths | prefix-list name | pending-prefixes | route-map name]

Good explanation document :

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13762-40.html