Posts Tagged ‘OSPF routing bit’

MPLS Layer 3 VPNs

September 10, 2012 21 comments

This post is the continuation of the previous post I made on Basic MPLS. In this post, I will talk about the different steps in order to configure MPLS Layer 3 VPNs which include the PE-CE routing protocols configuration with RIP, EIGRP and OSPF. I will also talk about the different loop prevention rules used when using OSPF as a PE-CE routing protocol. Finally I will conclude this post by talking about OSPF Sham-link.

 In this topic, I will use the following topology:

Platform/IOS: Cisco 2691/12.4(15)T11 Adv IP services


  • Customer A: VRF A | IGP: RIP
  • Customer B: VRF B | IGP: EIGRP
  • Customer C: VRF C | IGP: OSPF 2 Area 0
  • ISP: Core IGP: OSPF 1 Area 0 | MP-BGP AS 200

 Addressing: See topology. All the routers are configured with a Loopback IP and the format X.X.X.X /32 where X is the router number.

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