L3 VPN over SPBV

Using SPBV, the PE router is directly connected to its BGP peers, so an IGP (OSPF) is not needed. The required fully integrated services on the PE router for an SPBV network to establish are:

• VRF instance – Virtual Routing and Forwarding (VRF) provides for partitioning a router into segregated domains for the routed forwarding of packets.
• Route distinguisher (RD) – A 64 bit identifier prepended to the IP address making the address globally unique across the L3 VPN network and when stored in the MP-iBGP route table.
• Route target – An identifier that determines which routes are advertised by a VRF and inserted into a VRF.
• SPBV – A L2 protocol that assures data traffic transits a shortest cost path between any two switches in the SPBV region. SPBV is configured on all devices in the SPBV cloud including PE routers, and is enabled on all PE Global router ports.
• MP-iBGP – An internal multi-protocol border gateway routing protocol that carries the VPN routes and labels within a single autonomous system

There are two router types in a typical L3 VPN over SPBV network:

• Provider Edge (PE) router – These routers are the endpoints of the public network that:
  • Are configured for a VRF for each L3 VPN
  • Interconnect with other PE routers using SPBV configured in the global VRF
  • Directly connect and redistribute learned BGP L3 VPN routes to private customer routers over L2 and L3 links.
• Customer Edge (CE) router – These routers reside in the private customer network. When routes are learned on the PE from local CEs, they are redistributed to other PEs using IBGP.

  Imported L3 VPN routes learned on the PE router VRFs are redistributed to the customer edge routers using BGP.

Layer 3 VPN over SPBv Overview provides an overview of a L3 VPN over SPBV network. There are two L3 VPNs: Customer A on base-VLAN 100 and Customer B on base-VLAN 200.

Each PE router is configured for two VRFs, one for each L3 VPN. The L3 VPN for Customer A uses VRFs VRF1 and VRF3. The L3 VPN for Customer B uses VRF2 and VRF4. For a L3 VPN to operate, each VRF must be configured with an RD. Each VRF must be configured with at least one route target that imports or exports L3 VPN routes, or both imports and exports L3 VPN routes. Each PE must be configured for SPBV with SPBV enabled on all Global router ports. All devices within the SPBV cloud must be configured for SPBV. On each PE router, BGP must be configured at the global VRF to redistribute routes from each VRF to the linked CE router. The appropriate IPv4 or IPv6 BGP L3 VPN address family must be enabled. Within the appropriate BGP L3 VPN address family, activate each BGP neighbor.