Configuring the Layer 2.5 VPN
Layer 2.5 VPNs use essentially the same configuration format as Layer 2 VPNs. You should already have experience configuring Layer 2 VPNs before you attempt to configure a Layer 2.5 VPN. The major steps required to create a Layer 2 VPN are:
Enable MPLS on interfaces pointing toward the core and the edge on your provider edge (PE) and provider core (P) routers.
Configure Label Distribution Protocol (LDP) on all P and PE routers for traffic traveling from the PEs, through the core, and to the remote PEs.
Establish an internal BGP (IBGP) Layer 2 VPN peering relationship between PE routers.
Set up policies on your PE routers that will set a private community tag on outbound BGP traffic heading to the remote PEs and accept incoming traffic that matches similar community traffic from the remote PEs.
Build VPN routing and forwarding (VRF) instances on your PE routers and apply the previously configured policies to deliver private traffic to the customer edge (CE) routers.
In addition to the above configurations procedures, you can specify a Layer 3 protocol family for a Layer 2.5 VPN on T Series and M320 routers.