R3303-HP HSR6800 Routers MPLS Configuration Guide

154
Figure 39 CCC MPLS L2VPN network diagram
After you complete the configurations as shown in Figure 39, a static LSP from PE 1 to PE 2 and a static
LSP from PE 2 to PE 1 are established. Bind the two LSPs to Interface A on PE 1 and to Interface B on PE
2. A CCC connection is successfully established.
The following describes how a packet is forwarded from CE 1 to CE 2:
1. After PE 1 receives a packet from CE 1 on Interface A, it adds label 300 (corresponding to the
static LSP from PE 1 to PE 2) into the packet.
2. After the P device receives the packet, it looks up the label forwarding table, and swaps label 300
with label 310.
3. After receiving the packet, PE 2 deletes the label from the packet, and then forwards the packet out
of the bound interface Interface B to CE 2.
Unlike other MPLS L2VPN modes, CCC employs only one level of label to transfer user packets. A static
LSP forwards only packets from the AC bound to the static LSP. Therefore, CCC uses LSPs exclusively. LSPs
used by a CCC connection transfers only CCC connection data. They cannot be used by other
connections or MPLS L3VPN.
SVC MPLS L2VPN
SVC implements MPLS L2VPN by static configuration. It uses two levels of labels to transfer user packets.
The inner label is statically configured on PEs. No signaling protocol is used.
Martini MPLS L2VPN
Martini MPLS L2VPN employs two levels of labels to transfer user packets, and uses LDP as the signaling
protocol to distribute the inner VC label.
To exchange VC labels between PEs, Martini extended LDP by adding the VC FEC. The VC FEC contains
the following information:
• VC type—Encapsulation type of the VC. For more information, see "VC types."
• VC
ID—Identifier of a VC on a PE.
The VC type and the VC ID uniquely identify a VC. On a PE, the VC ID uniquely identifies a VC among
the VCs of the same type.
As shown in Figure 40, the P
Es send the VC FEC and VC label in a label mapping message to each other.
After the VC labels are distributed, a VC is set up between the PEs.