The Cooperative Route Filtering feature allows the user to move the filtering function of a route-target import filter to a peer. In this situation, an Outbound Route Filter (ORF) is derived from the contents of all of the route-target import commands of BGP configured VRFs on a PE and shared with a peer PE. This ORF is then used to exclude any routes that are blocked by that ORF from being sent by the peer PE to the PE with the route-target import commands from which the ORF was derived. For example, in the diagram below the routes that are admitted into VPN1 and VPN2 have route targets of 1:1 and 2:2. The user can use the cooperative route filtering feature to send an ORF that is derived from the route-target import commands on PE 1 to PE 2 to only accept these routes.
The following example shows the commands required to configure VRF VPN1 on PE 1 in the diagram above with an import route-target of 1:1 and VRF VPN2 on PE 1 with an import route-target import of 2:2.
device(config)# vrf VPN1
device(config-vrf-VPN1)# route-target import 1:1
device(config-vrf-VPN1)# exit-vrf
device(config)# vrf VPN2
device(config-vrf-VPN2)# route-target import 2:2
device(config-vrf-VPN2)# exit-vrf
The following commands configure PE 1 to send the filter derived from the import route-target commands in VPN1 and VPN2 to PE 2.
device(config-bgp)# address-family vpnv4 unicast
device(config-bgp-vpnv4u)# neighbor 10.3.3.2 capability orf extended-community send-vrf-filter
The following commands configure PE 2 to receive the filter derived from the import route-target commands in VPN1 and VPN2 on PE 1.
device(config-bgp)# address-family vpnv4 unicast
device(config-bgp-ivpnv4u)# neighbor 10.3.3.1 capability orf extended-community receive