Classification and Marking
The goal of classification and marking tools is to simplify the classification process of other QoS
tools by performing complicated classification steps as few times as possible. For instance, a
classification and marking tool might examine the source IP address of packets, incoming Class
of Service (CoS) settings, and possibly TCP or UDP port numbers. Packets matching all those
fields may have their IP Precedence (IPP) or DiffServ Code Points (DSCPs) field marked with
a particular value. Later, other QoS tools—on the same router/switch or a different one—can
simply look for the marked field when making a QoS decision, rather than having to perform
the detailed classification again before taking the desired QoS action.