PLANET XGS3-24042 - Manual (Page 672)

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Chapter 81 MPLS VPN
81.1 BGP/MPLS VPN Introduction
81.1.1 BGP/MPLS VPN Network Structure
BGP/MPLS VPN is a PE-based L3VPN technology in the VPN solutions provide by providers, using BGP to
advertise VPN routes and MPLS to forward VPN messages in the provider backbone network.
The BGP/MPLS VPN networking is flexible, extendible, and can support MPLS QoS and MPLS TE
conveniently, resulting in its increasingly popular application.
BGP/MPLS VPN model consists of three parts: CE, PE and P.
 P router: Provide Router. It locates in the MPLS domain, and is able to switch fast-forwarding MPLS
data flow based on labels. P router receives MPLS messages, switch labels and then output them.
 PE router: Provide Edge Router. It locates at the edge of the MPLS domain, for converting IP
messages and MPLS messages. PE router receives IP messages, pushes MPLSU labels, and
output MPLS messages; or receives MPLS messages, pop labels, and output IP messages. On PE
routers, the ports connected with other P routers or PE routers are “public network port”, configured
with public network IP address; those connected with CE routers are “private network port”,
configured with private network address.
 CE router: Customer Edge Router. It locates at the edge of the customer IP domain, connected
directly to PE route, for aggregating customer data and forwarding route information of the customer
IP domain to PE router.
The next figure demonstrates a BGP/MPLS VPN networking:
Figure 81-1 BGP/MPLS VPN Networking
The division of CE and PE is based on the management areas of SP and customers, since CE and PE are the
edge between the two areas.
CE is usually a router. When the adjacency between it and the PE directly connected to it, CE will advertise
VPN 1
site 1
2
CE
VPN 2
CE
PE
PE
VPN 2
2
CE
VPN 1
site 1
CE
PE
P P
P P
Provider MPLS Backbone
site site