l BGP (MP-BGP) sessions established between them to communicate VPN information. The provider edge routers store the routing updates from each customer's customer edge router in what is termed a virtual routing forwarding (VRF) instance; simply put, it is a routing table populated with VPN routes. Because there may be a great number of provider edge routers in a network, car- riers might also need to configure BGP route reflectors to simplify the internal BGP mesh. Route reflectors reduce the size of the internal BGP mesh. Route reflector Chapter 9 IP Services PE Device MP-BGP Control Session Route Reflector PE Device VRF I VRF 2 Provider Backbone VRF 3 PE Device MPLS LSP CE-PE Link PE = Provider Edge CE = Customer Edge Figure 9.23 The RFC 2547bis model clients propagate routes up to the route reflectors, which, in turn, send the routes to other route reflector clients. Route reflectors are useful in partitioning total routing table space across multiple devices. This allows the route reflector clients to receive only routes they need-not all the routes. Each customer edge router has its own VRF on the provider edge. The cus- tomer advertises all routes associated with that location to the provider edge. When all the provider edge routers that connect to a particular customer have the customer's routing information in a VRF, the provider edge routers exchange infor- mation by using MP-BGP. These routes and the corresponding VRFs make up the customer VPN. To the customer, from a routing perspective, the customer edge routers appear as if they are connected via a traditional VPN. The customer can view the routing table on the customer edge router and see routes to remote sites, just as it would with a traditional VPN. The routing adjacencies formed are between the customer edge and the provider edge, not the customer edge and the customer edge. The customer edge has one interface to the MPLS cloud, and the MPLS provides full or partial meshing with the customer edge router attached to the network. One of the benefi