MPLS L3VPN PE Router That Don't want to receive other routes

CCIE
1

Hi @KB-KBITS , Kbits Community,

Is there documentation or related forums available or if you guys know this scenario. Just curious on this, let’s say we have typical MPLS SP setup with PE edge routers (PE-1 and PE-2 + PE-X with P routers in the core) configured PE-1 with exporting the routes using “export RT” from multiple VRF into MP-BGP, what if for example I did not “import RT” this on the other PE-2 - while I still need this to be imported in other PE-X, in theory and from my understanding it should still send the BGP update from PE-1 to PE-2 and that’s not only imported to the proper VRF. My point is, what if we have overwhelming number of routes and multiple VRFs from PE-1 and I’m not having “import RT” for all VRFs on PE-2, the BGP updates are still being sent towards the other end. With this, is this a problem (CPU, memory ,etc) or if yes, what solution should be taken? Because let’s say this particular PE-2 has low end specs compared to other PE routers in SP domain, and I only need to import for some VRFs and not all. Just curious on this.

Thanks,
Cheers!

2

When a PE receives prefixes it doesn’t have an import policy for, the PE will drop them. To limit the updates to just prefixes that you do have an import policy for, you can use SAFI 132 (Route Target Constrain, RFC4684)). I believe it’s “address-family rtfilter unicast” on XE and “address-family ipv4 rtfilter” on XR.