Other MPLS Applications

The MPLS architecture, as discussed so far, enables the smooth integration of traditional routers and ATM switches in a unified IP backbone (IP+ATM architecture). The real power of MPLS, however, lies in other applications that were made possible, ranging from traffic engineering to peer-to-peer Virtual Private Networks. All MPLS applications use control-plane functionality similar to the IP routing control plane shown in Figure 1-6 to set up the label switching database. Figure 1-7 outlines the interaction between these applications and the label-switching matrix.

Every MPLS application has the same set of components as the IP routing application:

• A database defining the Forward Equivalence Classes (FECs) table for the application (the IP routing table in an IP routing application)

• Control protocols that exchange the contents of the FEC table between the LSRs (IP routing protocols or static routing in an IP routing application)

• Control process that performs label binding to FECs and a protocol to exchange label bindings between LSRs (TDP or LDP in an IP routing application)

• Optionally, an internal database of FEC-to-label mapping (Label Information Base in an IP routing application)

Each application uses its own set of protocols to exchange FEC table or FEC-to-label mapping between nodes. Table 1-2 summarizes the protocols and the data structures.

The next few chapters cover the use of MPLS in IP routing; Part II, "MPLS-based Virtual Private Networks," covers the Virtual Private Networking application.