Traditional bridges treated all frames the same way—first come, first served. But the importance of user traffic varies. Some carries mission-critical inter-active data. Some consists of background file transfers that can tolerate delays.
The capability to prioritize traffic has been high on the customer wish list for quite a long time. Each vendor has met this need in a different way. Some products allow customers to give a type of traffic either high or low priority. Some support many priority classes. Depending on the product, customers may be able to assign traffic to a priority class according to the following:
Protocol (such as IP, IPX, TCP, UDP, DECnet, or SNA)
Application (as defined by a TCP or UDP ...