[Contents] [Prev] [Next] [Index] [Report an Error]

Enabling VRF–to–VR Peering

In some circumstances you might want a CE router, which connects to the PE router by means of a VRF, to be able to establish an EBGP peering session directly with the parent VR in which the VRF has been configured. The global instance of BGP for the PE router runs in the parent VR to exchange VPN routes with its peers by means of internal or external MP-BGP. BGP could also be learning IPv4 unicast Internet routes from one or more of its core-facing, internal or external BGP peers.

In the context of the VRF, you can use the ip route parent-router command to add a static host route to a stable interface (typically a loopback interface) in the parent VR by way of a hidden VRF-internal interface.



host1(config)#virtual-router PE1 

host1:PE1(config)#interface loopback 1 

host1:PE1(config-if)#ip address 10.20.20.2
255.255.255.255 

host1:PE1(config-if)#exit 

host1:PE1(config)#virtual-router :PE11 

host1:PE1:PE11(config)#ip route parent-router
loopback 1

In this example, assume that the global instance of BGP for the PE router runs in the parent VR, PE 1, to exchange VPN routes with its peers by means of internal or external MP-BGP. BGP can also be learning IPv4 unicast Internet routes from one or more of its core-facing, internal or external BGP peers.

By virtue of the static route configured in VRF PE 11, a CE router that connects to that VRF can establish an EBGP session directly to loopback 1 (10.20.20.2) in the parent VR, PE 1. The same PE router can therefore provide both VPN and Internet access to any attached CE routers.

You can display the static route to the parent VR with the show ip route and show ip static commands, as in the following examples:

host1:PE1:PE11#show ip route
Prefix/Length      Type    Next Hop           Dist/Met     Intf
------------------ ------- -----------------  ------------- ---------------
10.20.20.2/32     Static  0.0.0.0[V:PE1]   1/0          vrf-internal3        

host1:PE1:PE11#show ip static
Prefix/Length      Next Hop   Met   Dist    Tag   Intf
10.20.20.2/32      0.0.0.0    0     1       0     vrf-internal3

ip route

Use to establish a static route in a VRF to a remote interface in the parent VR.
The specified interface must be preexisting and have an alias assigned with the description command.
The route points to a next-hop interface that is internal to the VRF and created automatically when the VR comes up. This interface is hidden and cannot be displayed with the show ip interface command. You must use the show ip route or show ip static commands to display the interface.
If the interface in the parent VR goes down or is deleted, the static route added in the VRF will continue to exist.
Examplehost1(config-vrf)#ip route parent-router vr1stat
Use the no version to remove the static route.
See ip route.

[Contents] [Prev] [Next] [Index] [Report an Error]