METHOD FOR ASSIGNING PRIORITY TO TRAFFIC BETWEEN LOCAL AREA NETWORKS INTERCONNECTED VIA A BACKBONE NETWORK

摘要

The invention relates to a method for assigning piority to traffic between LANs (11) interconnected via a backbone network (12) and connected to the backbone network (12) over a transmission line (14a-14e). To be able to control the maximum delays especially with traffic having a high interactivity requirement, (a) the length of a frame (38) received from the LAN (11) is determined with a predetermined accuracy, thus obtaining at least two length categories having a respective priority status; (b) at least one address of a pair of addresses formed by the source and destination address of the received frame is compared with the corresponding addresses of frames currently waiting for transmission in a queue of frames with a lower priority status than the priority status corresponding to the length of said received frame, or frames which have been in said queue during a predetermined preceding period of time (Tp); (c) frames (39) to be forwarded are applied to at least two different transmission queues (33a, 33b) with different priority status on the basis of the classification into length categories and the address checking; (d) at least some of the frames to be transmitted are marked so as to distinguish the priority frames from the other frames; and (e) said marking is checked at a buffering point (P) and the frames are forwarded in accordance with the marked priority status.