Figure 52: Distribution of Routes from PE Routers to CE Routers
Understanding Layer 3 VPN Forwarding Through the Core
The PE routers in the provider’s core network are the only routers that are configured to
support VPNs and hence are the only routers to have information about the VPNs. From
the point of view of VPN functionality, the provider (P) routers in the core—those P routers
that are not directly connected to CE routers—are merely routers along the tunnel between
the ingress and egress PE routers.
The tunnels can be either LDP or MPLS. Any P routers along the tunnel must support the
protocol used for the tunnel, either LDP or MPLS.
When PE-router-to-PE router forwarding is tunneled over MPLS label-switched paths
(LSPs), the MPLS packets have a two-level label stack (see Figure 53 on page 827):
•
Outer label—Label assigned to the address of the BGP next hop by the IGP next hop
•
Inner label—Label that the BGP next hop assigned for the packet’s destination address
Copyright © 2017, Juniper Networks, Inc.826
ACX Series Universal Access Router Configuration Guide
To Next Page
Loading...
Need help?
General
