IMPROVED FLOW CONTROL AND QUALITY OF SERVICE PROVISION FOR FRAME RELAY PROTOCOLS

摘要

Apparatus and method for providing controlled Quality of Service over Ethernet-like links. Prioritised frames are allocated to transmission queues responsivetotheir priorities. Each queue has an associated subsidiary Ethernet MAC whichtransmits frames from its queue subject to a scheduler which selects from thesetof MAC's according to a pre-determined algorithm. The multiple logical pathsbetween corresponding pairs of transmitter and receiver subsidiary MAC's arepreferably multiplexed over a single physical channel. If congestion occurs atthe receiver, then Ethernet PAUSE frames may be sent back to the transmitter,directed to specific subsidiary MAC's - typically those with lower priority -tosuspend transmission from the corresponding queue for a time period indicatedin the PAUSE frame. In this way back pressure flow control may be appliedselectively to so that large amounts of low priority traffic do not causeunnecessary delays to higher priority traffic.