Overview

This chapter describes the architectural models that can be applied to GMPLS networks. These architectures are not only useful for driving the ways in which networking equipment is deployed, but they are equally important in determining how the protocols themselves are constructed, and the responsibilities of the various protocol components.

Several distinct protocol models have been advanced and the choice between them is far from simple. To some extent, the architectures reflect the backgrounds of their proponents: GMPLS sits uncomfortably between the world of the Internet Protocol and the sphere of influence of more traditional telecommunications companies. As a result, some of the architectures are heavily influenced by the Internet, while others have their roots in SONET/SDH, ATM, and even the telephone system (POTS).

The supporters of the different architectures tend to be polarized and fairly dogmatic. Even though there are many similarities between the models, the proponents will often fail to recognize the overlaps and focus on what is different, making bold and forceful statements about the inadequacy of the other approaches. This chapter does not attempt to anoint any architecture as the best, nor does it even try to draw direct comparisons. Instead, each architecture is presented in its own right, and the reader is left to make up her own mind.

Also introduced in this chapter is the end-to-end principle that underlies the IETF's Internet architecture and then describes three different GMPLS architectural models. The peer and overlay models are simple views of the network and...