Interdomain Traffic Engineering
In the Traffic Engineering chapter (Chapter 2), we have seen how to compute and signal traffic-engineered paths that comply with a set of user-defined constraints. A key step in this process is acquiring the information regarding the constraints for all the links in the network. This information is distributed by a link-state IGP and is therefore confined within the same boundaries as the link-state advertisements. Because the visibility of the topology and of the constraints is limited to a single IGP area, TE LSPs dynamically computed by the head end are also limited in the same way. This becomes a problem in large networks that deploy several IGP areas for scalability or in the case of services spanning across several service providers.
In this chapter we will see how RSVP-signaled TE LSPs can extend across IGP areas and across AS boundaries. These solutions are known as interarea TE and inter-AS TE respectively and are referred to collectively as interdomain TE. They apply equally to classic TE and to Diff-Serv Aware TE (described in the DiffServ-TE chapter, Chapter 4). In this chapter the term ‘domain’ is used to denote either an IGP area or an AS.
5.2 THE BUSINESS DRIVERS
The benefits of traffic engineering were discussed in the Traffic Engineering chapter (Chapter 2). Providers use traffic-engineered paths for optimization of network resources, support of services with QoS guarantees, fast reroute and the measurement of ...