How Mpls L3Vpn Works; Major Components Of Mpls L3Vpn - Cisco NCS 540 Series Configuration Manual

How MPLS L3VPN Works

• Provider (P) router—Router in the core of the provider network. P routers run MPLS switching and do
• PE router—Router that attaches the VPN label to incoming packets based on the interface or sub-interface
• Customer (C) router—Router in the Internet service provider (ISP) or enterprise network.
• Customer edge (CE) router—Edge router on the network of the ISP that connects to the PE router on the
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How MPLS L3VPN Works
MPLS VPN functionality is enabled at the edge of an MPLS network. The PE router performs the following
tasks:
• Exchanges routing updates with the CE router
• Translates the CE routing information into VPN version 4 (VPNv4) routes
• Exchanges VPNv4 routes with other PE routers through the Multiprotocol Border Gateway Protocol

Major Components of MPLS L3VPN

An MPLS-based VPN network has three major components:
• VPN route target communities—A VPN route target community is a list of all members of a VPN
• Multiprotocol BGP (MP-BGP) peering of the VPN community PE routers—MP-BGP propagates VRF
• MPLS forwarding—MPLS transports all traffic between all VPN community members across a VPN
A one-to-one relationship does not necessarily exist between customer sites and VPNs. A given site can be a
member of multiple VPNs. However, a site can associate with only one VRF. A customer-site VRF contains
all the routes available to the site from the VPNs of which it is a member.
Read more at
L3VPN Configuration Guide for Cisco NCS 540 Series Routers, IOS XR Release 6.3.x
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not attach VPN labels to routed packets. VPN labels are used to direct data packets to the correct private
network or customer edge router.
on which they are received, and also attaches the MPLS core labels. A PE router attaches directly to a
CE router.
network. A CE router must interface with a PE router.
How MPLS L3VPN Works, on page 2
How to Implement MPLS Layer 3 VPNs, on page 8
VRF-lite, on page 43
MPLS L3VPN Services using Segment Routing, on page 47
Implementing MPLS L3VPNs - References, on page 52
(MP-BGP)
community. VPN route targets need to be configured for each VPN community member.
reachability information to all members of a VPN community. MP-BGP peering needs to be configured
in all PE routers within a VPN community.
service-provider network.
Major Components of MPLS L3VPN—Details, on page
MPLS L3VPN Overview
52.