Fremgangsmåde til tildeling af prioritet til trafik mellem lokalnet, der er indbyrdes forbundne via et hovednet

PCT No. PCT/FI93/00393 Sec. 371 Date Apr. 4, 1995 Sec. 102(e) Date Apr. 4, 1995 PCT Filed Oct. 1, 1993 PCT Pub. No. WO94/08411 PCT Pub. Date Apr. 14, 1994A method for assigning priority to traffic between LANs interconnected via a backbone network and connected to the backbone network over a transmission line. To be able to control the maximum delays, especially with traffic having a high interactivity requirement, (a) the length of a frame received from the LAN 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 the received frame, or frames which have been in the queue during a predetermined preceding period of time (Tp); (c) frames to be forwarded are applied to at least two different transmission queues 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) the marking is checked at a buffering point, and the frames are forwarded in accordance with the marked priority status.