Introduction
Overview
Traffic Classification
Traffic classification filters packets in a traffic stream into distinct classes (groups) based on the content of parts of the packet header. In the classification process, IP packets are matched against selectors of each filter to determine if the packet belongs in that filter class. Traffic classifiers separate and steer traffic classes to traffic conditioners for further processing.
Two types of classifiers are defined in the DiffServ model. The Behavior Aggregate (BA) Classifier selects packets based on the DSCP only. The
Traffic Conditioning
Traffic conditioning consists of one or more of the following actions:
Metering | Metering is part of the flow control strategy. Flow control measures traffic |
| flow for a class, then releases packets onto the network at a specified rate. |
| The metering component ensures conformance to configured flow rates. |
| Metering measures the traffic stream against a traffic profile specified via |
| policies in |
| |
| flow rates, and passes state information to other conditioning functions to |
| trigger a specific action for each packet. |
| With |
| bandwidth; you can also specify a maximum bandwidth. See “Policy |
| Attributes” on page 71 for more information. |
Marking | Marking marks packets with values that translate to forwarding behaviors. |
| Marking is the basis for potential differentiated treatment when the packet |
| reaches a resource that recognizes the marking, such as a |
| Forwarding behavior determines the priority and drop precedence of traffic |
| about to be forwarded on the network. This can involve marking or |
| |
| It can also involve marking or |
| frame header with a Class of Service (CoS) priority value. |
| After a value is placed in the packet header, the packet forwarding behavior |
| is determined by the forwarding scheme used by |
| network. For example, different traffic classes can be steered to use |
| different routes such as |
| links. The steering depends on forwarding rules set in the |
Chapter 1 | 21 |