MPLS-Enabled Applications: Emerging Developments and New Technologies

4.6. CONCLUSION

Differentiated Services (DiffServ) provides QoS by dividing traffic into a small number of classes and allocating network resources on a per-class basis. MPLS-TE enables resource reservation and optimization of transmission resources. MPLS DiffServ-TE combines the advantages of both DiffServ and TE, while at the same time benefiting from the fast-reroute mechanisms available for MPLS.

The result is the ability to set up traffic-engineered LSPs with pertraffic-class granularity and to guarantee resources for each particular type of traffic. Equipment vendors offer mechanisms to map traffic to the appropriate LSPs based on flexible policies, as well as tools for ensuring that traffic stays within the limits of the resources that were reserved for it. Thus, strict QoS guarantees are achieved both for the steady state and the failure cases. Based on the service guarantees that are achieved, service providers can offer services with high SLA requirements, such as voice or migration of ATM/FR on to an MPLS core.

However, as discussed so far, both TE and DiffServ-TE are limited in their scope to a single IGP area and a single AS. In the next chapter, we will see how this limitation can be overcome by Interdomain TE.