Traffic Engineering Within the USCom Network
As established earlier in the "QoS Design in the Core Network" section, one of the fundamental network design rules adopted by USCom is the overprovisioning of available network resources, hence ensuring bounded link utilization in the core. This implies the following:
- Sufficient bandwidth must be provisioned in the core optical network.
- The metrics used by IGP (IS-IS in the case of USCom) must be computed so as to efficiently balance the traffic load in the core. In other words, traffic engineering is achieved through manipulating the IGP metrics. To ensure that link utilization remains below 40 percent in the absence of failures at all times, USCom decided to develop an internal tool that computes a set of IS-IS metrics that are used to traffic-engineer the network. The tool is run on a regular basis (approximately every 6 months) to accommodate some traffic growth. It is triggered by the monitoring of link utilization in the network by the USCom management system.