RFC 3346 (rfc3346) - Page 3 of 14
Applicability Statement for Traffic Engineering with MPLS
Alternative Format: Original Text Document
RFC 3346 Applicability Statement for Traffic Engineering August 2002 2. Technical Overview of ISP Traffic Engineering Traffic engineering (TE) is generally concerned with the performance optimization of operational networks [2]. In contemporary practice, TE means mapping IP traffic flows onto the existing physical network topology in the most effective way to accomplish desired operational objectives. Techniques currently used to accomplish this include, but are not limited to: 1. Manipulation of IGP cost (metrics) 2. Explicit routing using constrained virtual-circuit switching techniques such as ATM or Frame Relay SPVCs 3. Explicit routing using constrained path setup techniques such as MPLS This document is concerned primarily with MPLS techniques. Specifically, it deals with the ability to use paths other than the shortest paths selected by the IGP to achieve a more balanced network utilization, e.g., by moving traffic away from IGP-selected shortest paths onto alternate paths to avoid congestion in the network. This can be achieved by using explicitly signaled LSP-tunnels. The explicit routes to be used may be computed offline and subsequently downloaded and configured on the routers using an appropriate mechanism. Alternatively, the desired characteristics of an LSP (such as endpoints, bandwidth, affinities) may be configured on a router, which will then use an appropriate algorithm to compute a path through the network satisfying the desired characteristics, subject to various types of constraints. Generally, the characteristics associated with LSPs may include: o Ingress and egress nodes o Bandwidth required o Priority o Nodes to include or exclude in the path o Affinities to include or exclude in the path o Resilience requirements Affinities are arbitrary, provider-assigned, attributes applied to links and carried in the TE extensions for the IGPs. Affinities impose a class structure on links, which allow different links to be logically grouped together. They can be used to implement various types of policies, or route preferences that allow the inclusion or exclusion of groups of links from the path of LSPs. Affinities are unique to MPLS and the original requirement for them was documented in [2]. Boyle, et al. Informational
