MPLS-Enabled Applications: Emerging Developments and New Technologies

6.5. COUPLING TRAFFIC INTO A P2MP LSP

The previous sections described how a P2MP LSP is created. Let us now examine how traffic can be coupled into a P2MP LSP at the ingress node. We consider three categories of traffic: Layer 2 traffic, IP traffic having a unicast destination address and IP traffic having a multicast destination address. All three categories apply to video applications, because for each there exist examples of commercially available video equipment that encapsulate video flows into packets of that format.

6.5.1. Coupling Layer 2 traffic into a P2MP LSP

One application for P2MP LSPs is to carry Layer 2 traffic such as ATM. For example, some encoders encapsulate digital TV signals into ATM AAL1 frames. With a native ATM network, point-to-multipoint VCs are often used to distribute the traffic to multiple destinations. When using an MPLS network, P2MP LSPs provide the analogous function, allowing the Layer 2 traffic to be distributed to multiple receivers in a bandwidth-efficient manner.

An existing implementation achieves this by using a point-to-multipoint version of the Circuit Cross Connect (CCC) [CCC] scheme described in the Layer 2 Transport chapter (Chapter 10). In this scheme, a binding is created, through configuration, between an incoming Layer 2 logical interface (e.g. an ATM VC or an Ethernet VLAN), known as an attachment circuit, and a P2MP LSP at the ingress router. Similarly, at the egress routers, a binding is created between the P2MP LSP and the ...