■The customer carrier’s PE routers that connect to the provider’s VPN use LDP
to exchange labels for the internal routes between themselves and the provider
carrier’s PE router.
■The customer carrier’s PE routers that connect to the provider’s VPN learn
external routes through IBGP sessions among themselves.
Figure 107 on page 471 shows a sample carrier-of-carriers environment in which the
customer carrier provides Internet connectivity services to its customers. The figure
shows how the labels are added and removed as the traffic traverses the network.
The label-signaling protocol is assumed to be LDP.
Figure 107: Carrier-of-Carriers Internet Service
Configuration Steps
You must complete the following configuration process when the customer carrier
provides Internet connectivity for its customers.
On the provider carrier’s PE router:
Carrier-of-Carriers IPv4 VPNs â– 471
Chapter 5: Configuring BGP-MPLS Applications