Technical Documentation

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. See the Option: Configuring ISO or MPLS Traffic on T Series, M320, and MX Series Routers section for configuration information.

Published: 2010-04-15