area sham-link

Use this command to configure an OSPF sham link between two PE routers.

Syntax

area area-id sham-link source-ip-address destination-ip-address
no area area-id sham-link source-ip-address destination-ip-address

Parameters

area-id Specifies the OSPF area the two PE routers belong to.
source-ip-address Specifies the source IPv4 address for this sham link.
destination-ip-address Specifies the destination IPv4 address for this sham link.

Defaults

None.

Mode

VRF configuration, OSPF router configuration.

Usage

If a VRF contains both an OSPF-distributed route and a VPN-IPv4 route for the same IPv4 prefix, then the backdoor OSPF-distributed route is preferred over the VPN backbone route, unless the next hop interface for an installed (OSPF distributed) route is the sham link, in which case, the VPN backbone VPN-IPv4 route is used.

If it is desired to have OSPF prefer the routes through the VPN backbone over the routes through the OSPF backdoor link, then the routes through the backbone must appear to be intra-area routes. The sham link provides this appearance of an intra-area link connecting the two PE routers.

The “no” form of this command deletes the configured sham link.

Example

This example shows how to configure a sham link between two PE routers with a source address of 172.16.1.10 and a destination address of 172.16.2.20 on OSPF router instance 10, VRF doc:

System(su)->router doc
System(su-doc)->configure
System(su-doc-config)->router ospf 10
System(su-doc-config-ospf-10)->enable-pe-ce
System(su-doc-config-ospf-10)->area 10 sham-link 172.16.1.10 172.16.2.20