Filters are sets of rules that contain parameters called selectors. Each filter must point to a class. IPQoS matches packets against the selectors of each filter to determine if the packet belongs to the filter's class. You can filter on a packet by using a variety of selectors, for example, the IPQoS 5-tuple and other common parameters:
Source address and destination addresses
Source port and destination port
Differentiated Services Codepoint (DSCP)
For example, a simple filter might include the destination port with the value of 80. The ipgpc classifier then selects all packets that are bound for destination port 80 (HTTP) and handles the packets as directed in the QoS policy.
For information on creating filters, see How to Define Filters in the QoS Policy.