Configuring OSPF Sham Link

This section describes how to configure the routes that traverse the MPLS VPN backbone network to be the routes of the OSPF area. After the configuration, traffic between sites of the same VPN in the same OSPF area need not be forwarded through routes of the OSPF area.

Setting the Loopback Address of the Sham Link: The end address of a sham link is the IP address (with the 32-bit mask) of a loopback interface. The loopback interface must be bound to the VPN instance. The end addresses of sham links of the same OSPF process can be the same. The end addresses of sham links of different OSPF processes must be different.

Advertising Routes Destined for the End Address of the Sham Link: The route destined for the end address of the sham link cannot be advertised to the remote PE through the OSPF process of the VPN. The end address of the sham link is advertised to the remote PE by BGP as a VPNv4 address.

Creating a Sham Link: Creating a sham link is to establish a virtual link that connects the two end addresses of the sham link.