R2511-HP MSR Router Series MPLS Configuration Guide(V5)

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Configuring L2VPN access to L3VPN or IP
backbone
MPLS L2VPN that provides point-to-point connections supports the L2VPN access to L3VPN or IP
backbone feature. For more information about MPLS L2VPN and MPLS L3VPN, see "Configuring MPLS
L2VPN" and "Configuring MPLS L3VPN."
Unless otherwise specified, the term "MPLS L2VPN" in this chapter refers to MPLS L2VPN that provides
point-to-point connections.
Overview
MPLS L2VPN provides Layer 2 VPN services on an MPLS network. An MPLS L2VPN transparently
transfers Layer 2 user data across an MPLS network. For users, the MPLS L2VPN network is transparent,
and an MPLS L2VPN tunnel is a physical link for connecting users directly.
An MPLS L2VPN can serve as an access network to connect users to the MPLS L3VPN or IP backbone.
An MPLS L2VPN access network has the following advantages:
• Transparency—An MPLS L2VPN is transparent to users and can be regarded as a physical link that
directly connects users to the backbone.
• Lower networking cost—On an MPLS L2VPN access network, only PEs need to identify users and
user services. The P devices only forward packets based on labels and therefore can be low-end
devices. Deploying an MPLS L2VPN as the access network helps reduce your networking cost.
• Flexible networking—MPLS L2VPN supports various user access modes, such as Ethernet, ATM,
and frame relay. It also supports the interworking function.
The L2VPN access to L3VPN or IP backbone feature can be implemented in two modes: conventional
and improved mode.
Conventional L2VPN access to L3VPN or IP backbone
Figure 103 Network diagram for conventional L2VPN access to L3VPN or IP backbone
CE 2
MPLS L3VPN/
IP backbone
CE in MPLS L2VPN/
PE 3 in MPLS L3VPN
PE 4
MPLS L2VPN
access network
PE 1 PE 2
CE 1
VPN 1
Site 1
VPN 1
Site 2
Access Int
Terminating Int