A traffic control strategy for a DQDB-type MAN

Abstract

The joint problem of admission control of isochronous traffic and bandwidth sharing between isochronous and asynchronous traffic is addressed, in a MAN environment of the DQDB type. Local access controllers at the users' sites independently decide on the acceptance of each new isochronous call be applying a randomized decision rule. A central controller periodically reassigns bandwidth partitions (in slots/frame) between isochronous and asynchronous traffic, as well as upper bounds on the isochronous slots assigned on a per-user basis. This assignment is obtained by means of a parametric optimization that acts on a number of parameters characterizing the local decision rules, in order to minimize a suitable cost function, and depends on the overall system's state at the intervention time. The problem is formalized, and the application of a gradient projection method is considered, with cost functions spanning a finite or even infinite future time horizon.<>