1. A method of forwarding external packets onto connections at a medium access control layer between two communicating entities at the wireless interface of a broadband wireless access system, comprising: classifying the external packets at the medium access control layer to obtain a classification result by using a set of classification rules identified by a rule index and associated with a priority index determining an order of application of different classification rules to the external packets relating to a same service, the set of classification rules including both protocol-specific classification rules, containing one or more protocol-specific parameters to be matched by corresponding fields in a packet being classified, and a pass-through classification rule only containing a priority index and a rule index, but no protocol-specific matching parameter; and forwarding the external packets based on the classification result.