One of the most immediate benefits of MPLS is the ability to perform traffic engineering. Traditionally, the only mechanism for redirecting traffic has been to change the link metrics in the Interior Gateway Protocol (IGP, responsible for routing within a site), but this can potentially change the paths of all the packets traversing that link. With MPLS there is a finer granularity because it does not operate on a link basis and therefore it is possible to shift individual LSPs from congested paths to an alternate path. This also simplifies the operation of the network operator since the network operator can assign global optimization algorithms that provide mapping from the traffic demand to the physical link that could not be done using local optimization. Constraint-based routing (or its variant Explicit Routing ER) allows for traffic engineering. What is important, however, is that ER can allow for distributed routing of the same type as the routing and wavelength assignment in the optical adaptation layer. Furthermore, constraint-based routing use topology/resources updates to perform distributed LSP route computations, which can be used to deploy distributed shortest-path lightpath routing. A detailed comparison between distributed path routing strategies based on traffic parameters and fix path routing schemes is presented in this paper and it is shown that a distributed path routing scheme based on traffic correlation parameter is superior than fix path routing schemes.

Date Published: 25 October 2004
PDF: 12 pages
Proc. SPIE 5598, Performance, Quality of Service, and Control of Next-Generation Communication Networks II, (25 October 2004); doi: 10.1117/12.571712

Published in SPIE Proceedings Vol. 5598:
Performance, Quality of Service, and Control of Next-Generation Communication Networks II
Frank Huebner; Robert D. van der Mei, Editor(s)