MPLS-Enabled Applications: Emerging Developments and New Technologies

14.3. MODELS FOR MPLS DEPLOYMENT IN ACCESS NETWORKS

Let us now examine the way in which the MPLS deployed in the access network relates to the way MPLS is deployed in the core network. Two main options are possible, called Option 1 and Option 2. They differ in terms of where the Service Delivery Point (SDP) is located. SDP is a generic term to describe the various types of network equipment on which the specifics of the service relating to each individual customer are located. Examples of an SDP are as follows:

1. In the case of DSL, the SDP can be a Broadband Services Router (BSR). This is the point at which the subscriber is identified, authenticated and where policies such as the access rate are applied. As we shall see later, in some DSL architectures an additional SDP may be used, for example a Video Services Router (VSR) for video services.

2. In the case of MPLS VPN services offered to enterprise customers, the SDP is the PE router. For example, in the L3VPN case, the VRFs containing the customers' routes are here, and inbound policing and outbound shaping and queuing are applied here.

In the case of Option 1, the SDPs are located in the same location as they were before the MPLS metro network was built. Hence, the MPLS metro network is being used as a backhaul method to transport traffic from the edge to the SDPs, as a direct replacement for the previous access schemes. This is illustrated in Figure 14.2.

Figure 14.2. Separate MPLS access and MPLS core network

The advantage ...