190
Configuring MPLS L2VPN
This chapter describes how to configure MPLS L2VPN.
MPLS L2VPN overview
MPLS L2VPN is an MPLS-based Layer 2 VPN technology. It uses MPLS to establish Layer 2 connections
between network nodes.
Using MPLS L2VPN, carriers can transparently transport Layer 2 data of different data link layer
protocols (including ATM, FR, VLAN, Ethernet, and PPP) over a single MPLS or IP backbone.
For the perspective of users, the MPLS or IP backbone network is a Layer 2 switched network. For example,
when two Ethernet networks are connected through MPLS L2VPN over an MPLS or IP backbone, Ethernet
users cannot sense the existence of the MPLS or IP backbone. They feel like they are connected directly
through an Ethernet.
MPLS L2VPN can provide both point-to-point connections and point-to-multipoint connections. This
chapter describes only the MPLS L2VPN technologies that provide point-to-point connections. For
information about the MPLS L2VPN technologies that provide point-to-multipoint connections, see
"Configuring VPLS."
MPLS L2VPN has the following advantages:
• High scalability—MPLS L2VPN establishes only Layer 2 connections. It does not maintain the
routing information of users. This greatly reduces the load of provider edge (PE) devices and even
the load of the whole service provider network, enabling carriers to support more VPNs and to
service more users.
• Guaranteed reliability and VPN routing security—MPLS L2VPN neither tries to obtain nor
processes the routing information of users, guaranteeing the security of user VPN routing
information.
• Support for multiple network layer protocols—Such as IP, IPX, and SNA.
Basic concepts
• Customer edge device—A CE device is a customer network device directly connected to the service
provider network. It can be a netowork device (such as a router or a switch) or a host. It cannot
"sense" the existence of any VPN, neither does it need to support MPLS.
• Provider edge device—A PE device is a service provider network device connected to one or more
CEs. It provides VPN access by mapping and forwarding packets from user networks to public
network tunnels and from public network tunnels to user networks.
On an MPLS network, all VPN processing occurs on PEs.
• Attachment circuit—An AC is a link between a CE and a PE.
• Virtual circuit—A VC is also called a Pseudowire (PW). It is a virtual bidirectional connection that
connects the ACs on two PEs. An MPLS VC comprises a pair of LSPs in opposite directions.
• Tunnel—A tunnel (or public tunnel) is a connection that carries a VC across the MPLS or IP
backbone. It can be an LSP tunnel, MPLS TE tunnel, or a GRE tunnel.
To Next Page
Loading...
Need help?
General
