TABLE OF CONTENTS A typical application includes the traffic management elements illustrated in Figure 13.1 and described in the following sections.
Classifiers classify packets based on fields in the packet header. While applications also use classifiers for packet filtering, the goal of classification in the traffic management scenario is to identify the flow and the class for the packet. In addition, the classifier may also return the incoming drop precedence or color of the packet. The difference between flow and class is granularity. Flows usually reflect fine-grain classification for example, all packets belonging to the same TCP connection or all packets belonging to the same MPLS label switched path (LSP). The class identifier, on the other hand, is coarse-grained and reflects the aggregation of multiple flows for example, all packets with the same TOS/DSCP field. Applications typically use fine-grain flow classification for packet filtering and policing, while the class identifiers along with the color determine the queuing and buffer management policy applied to the packet.
Chapter 12 describes the implementation of different types of classifiers on processors in the IXP2XXX Product Line.
Meters or policers measure the arrival rate of packets or cells on an incoming flow and check it for conformance to a configured traffic profile. For out-of-profile packets, the meter either demotes the packet by lowering its drop precedence or discards it. In addition, a marker block may also update the packet header based...
