3Com 3C13636 Configuration Manual page 964

3Com Router 3000 Ethernet Family
Configuration Guide
draft-martini-l2circuit-trans-mpls-08.txt
draft-kompella-ppvpn-l2vpn-01.txt
The Martini draft provisions the point-to-point link implementation of L2VPN. As LDP is
used as the signaling protocol for the VC label transmission between the participating
parties, this implementation is called LDP/MPLS L2VPN.
Kompella draft provisions how to establish L2VPN end to end (CE-CE) over an MPLS
network. So far, it adopts BGP as the signaling protocol to advertise the L2-reachable
information and VC labels. Therefore, this implementation is always mentioned as
BGP/MPLS L2VPN.
In addition, L2VPN service can be provided by configuring static VC labels rather than
signaling. CCC is one approach for statically configuring L2VPN.
I. Introduction to CCC
Circuit Cross Connect (CCC) implements L2VPN through static configuration.
Compared with the conventional MPLS L2VPN, CCC uses one tier of label for user
data transmission. Therefore, its use of LSP is exclusive, and a user must manually
configure two LSPs for each CCC connection, with one for each direction. These two
LSPs can only be used for transmitting the data on this CCC connection and cannot be
used on other L2VPN connections. Besides, they cannot be used on BGP/MPLS VPN
or for carrying IP packets.
The major benefit for CCC mode is no special signaling is require to transmit L2 VPN
information as long as MPLS forwarding is available. In addition, QoS is guaranteed for
the LSP is privately leased.
II. MPLS L2VPN in SVC mode
Static Virtual Circuit (SVC) mode is in essence a static implementation of Martini mode.
The difference is that in SVC mode the VC labels are configured manually, while LDP is
not used as the signaling to transmit L2VC and link information.
III. MPLS L2VPN in Martini mode
Martini mode uses extended LDP (Martini draft extends LDP and adds VC FEC) as the
signaling to transmit VC information. This mode identify a VC using VC-TYPE+VC-ID,
where VC-TYPE stands for link-layer encapsulation type and VC-ID must be unique in
a PE. A PE connecting two PEs uses LDP to exchange VC labels and binds together
the corresponding CEs via the VC-ID. After established, a VC can transmit L2 data for
two CEs.
Unlike CCC mode, Martini mode does not support local switching function. Besides, it
also owns no privately leased LSP, but a LSP shared by many VCs.
In comparison with Kompella mode, it detects faults in a faster way, for it is not based on
regular refreshing mechanism.
3Com Corporation
4-4
Chapter 4 MPLS L2VPN Configuration