Principles of Broadband Switching and Networking

8

NETWORK TRAFFIC CONTROL AND BANDWIDTH ALLOCATION

A broadband integrated network carries a large volume of traffic, and the traffic may be from many different types of sources and have diverse characteristics. It is necessary to allocate network resources and control this traffic to achieve two fundamental goals:

• Satisfy the QoS (quality of service) requirements of network users.
• Maximize network usage.

Controls at different timescales are exercised to achieve these two goals. Recall that many logical networks can be set up on the same physical network by VP networking. Control can be exercised on the VPs in logical networks. Each logical network can be used by many end users who establish VCs over it, so we also have control at the VC connection level. Finally, the delivery of cells over a VC must also be controlled to meet certain QoS objectives, such as delay and cell loss probability.

In a virtual-path (VP) network, the virtual paths and the bandwidths on them may be reconfigured dynamically over time. For instance, if VPs are used to segregate services, different services may demand different amount of network resources at different times of the day. To maximize network usage and service quality, bandwidths can be reallocated once in a while (say, every half hour or so) among the different logical networks according to their usage. In addition, new VPs may be set up and old VPs may be torn down in a logical network dynamically to reflect the change in traffic demands within ...