ZyXEL XGS4700-48F User Guide - Page 352

Chapter 39 Differentiated Services kinds of traffic can be marked for different priorities of forwarding. Resources can then be allocated according to the DSCP values and the configured policies. 39.1.2 DiffServ Network Example The following figure depicts a DiffServ network consisting of a group of directly connected DiffServ-compliant network devices. The boundary node (A in Figure 182) in a DiffServ network classifies (marks with a DSCP value) the incoming packets into different traffic flows (Platinum, Gold, Silver, Bronze) based on the configured marking rules. A network administrator can then apply various traffic policies to the traffic flows. For example, one traffic policy would be to give higher drop precedence to one traffic flow over others. In our example packets in the Bronze traffic flow are more likely to be dropped when congestion occurs than the packets in the Platinum traffic flow as they move across the DiffServ network. Figure 182 DiffServ Network A PGS B P - Platinum G - Gold S - Silver B - Bronze SGP P S B B S GP P 39.2 Two Rate Three Color Marker Traffic Policing Traffic policing is the limiting of the input or output transmission rate of a class of traffic on the basis of user-defined criteria. Traffic policing methods measure traffic flows against user-defined criteria and identify it as either conforming, exceeding or violating the criteria. Two Rate Three Color Marker (TRTCM, defined in RFC 2698) is a type of traffic policing that identifies packets by comparing them to two user-defined rates: the Committed Information Rate (CIR) and the Peak Information Rate (PIR). The CIR 352 XGS4700-48F User's Guide