Friday, November 14, 2008

MPLS VPNs with RIPv2 Complete

Wow, I actually am getting better at this MPLS stuff. When moving from static routes to RIP, the complexity increases greatly. It's a good thing RIP itself is such a simple protocol.

So the main difference here is that address-families must be created under global RIP process. All the configuration is then applied under each RIP address-family. I found it very interesting at first that none of the redistribution in BGP or RIP requires the naming of the address-family. The router is smart enough to keep track of all this based on the address-family it is under, and the vrf assigned to the interface.

For example, when I first configured RIP, I was concerned about the network statement. Being that multiple interfaces fell under 10.0.0.0, I thought all of the interfaces would be advertised into the particular address-family of RIP and that I'd have to use passive-interface or filtering to block them. Nope. The router only advertises the interfaces that have the vrf of the applicable address-family. Makes perfect sense, and makes my life a lot easier.

I also got stuck for a bit because I couldn't find the RIP routes getting distributed into BGP. Turns out I needed to use sh ip bgp vpnv4 vrf instead of sh ip bgp. Makes sense, as I needed to see the routing table of the vrf instance, not the global bgp table.

I'm feeling a lot better about MPLS VPNs today, and have a better understanding the significance of route descriptors as well.

1 comment:

US VPN said...

I also have this problem with my VPN but I'll be sure to try this over the weekend. Thanks