Link layer multi-priority frame forwarding

Abstract

With increasing demand for multimedia and real-time applications, local area network (LAN) technologies are rapidly being upgraded to support Quality-of-Service (QoS). Many QoS-enabled LANs are making use of resource allocation mechanisms that can discriminate among traffic classes of different priorities. When such LANs are interconnected by bridges to form an extended LAN, it is necessary to upgrade the bridges so that they are QoS-enabled as well. For example, the IEEE 802.1p standard defines a framework for priority queuing in bridges. Alternatively, frame forwarding decisions at the link layer may be modified to recognize frame priorities and alternate paths may be used for differentiating QoS. In this paper, we describe a novel bridge protocol that can forward frames of different priorities using different paths. Our protocol ensures that the forwarding path of a higher priority frame is never longer than the forwarding path of a lower priority frame.