Any Way To Block or Bypass Specific BGP Network Advertisements?

[RRatBB]

IP addresses have been cleaned (RFC 1918).

We have 5 locations on an MPLS network. All locations advertise their networks through BGP.

When we signed up with our phone service, we thought it would make sense to have them on our MPLS network as well. So now *they* also are advertising their BGP route to us.

B 192.168.128.38 [20/0] via 10.5.1.1, 7w0d

We want to try taking our phones off of MPLS and using straight internet. But as long as our phone provider is advertising their routes to use MPLS as the next hop, we cannot really do that.

To summarize: I want our routers to ignore the phone provider's BGP route and use our default route (internet) instead.

The only way I can think to do this is:

1. Work with our phone provider and ask them to stop advertising their route to us.
2. Maybe put in static routes on our routers?

ip route 192.168.128.38 255.255.255.255 10.11.11.1 (gateway of last resort)

Would #2 work? I'd rather not deal with our ISP just yet.

Any easier/cleaner options?

Thanks

[Harold Ritter · Accepted solution]

Hi @RRatBB ,

Using a static route as mentioned would work, but would not be ideal, as the next hop could go down and traffic would go back to the MPLS network. 

You could filter out this specific route by putting a BGP ingress route policy on the CE router.

Regards,

[paul driver]

Hello
You could policy base route your internal users to route via your internet breakout next-hop for the voice traffic however the return traffic would  most probably come back in via the mpls unless your voice SP changes the way it routes to you, I would say applying some static routing would have the same result.

In the long term it would be applicable to work with your SP.