MPLS traffic engineering in OSPF networks—A combined approach

Abstract

One of the main reasons for the development of MPLS was the need for flexible Traffic Engineering (TE) in IP networks ([8], [1]). Additionally a lot of IP service providers have found that TE of their networks can have a tactical and strategic value [2]. The first part of the paper introduces a linear optimization approach for TE in MPLS networks. Most remarkable on the presented approach in comparison to other linear approaches is the additive objective function, which optimizes both the maximum utilization as well as the average utilization. In practice, most of the existing OSPF or IS-IS networks will have a transition phase between the pure IGP routing and the MPLS driven approach. Thus, we extend our optimization approach from a regular IGP network to a mixed IGP-MPLS environment. To avoid configuration complexity and state space explosion in MPLS devices, it could also make sense to start with a MPLS environment and take advantage of the configuration simplicity and the state space reduction capability of IGP protocols. In addition the paper includes a performance comparison between default configured OSPF, weight optimized OSPF and pure MPLS networks and shows the benefit of OSPF optimization and MPLS TE. Based on this comparison we can offer some valuable clues to decide in favor of a local or global TE system.