MPLS Fundamentals

Packet Forwarding

This section, illustrated with a specific example, looks at the life of an IP packet as it traverses the MPLS VPN backbone from one customer site to another. The basic building blocks of MPLS VPN need to be in place first. Multiprotocol iBGP needs to run between the PE routers that are distributing the vpnv4 routes and their associated VPN label. A label distribution protocol needs to exist between all the PE and P routers. This example assumes that the label distribution protocol is LDP. Between the PE and the CE routers, a routing protocol needs to run and put the customer routes into the VRF routing table on the PE routers. Finally, those routes need to be distributed into MP-iBGP and vice versa. Look at Figures 7-17 and ...