Providing QoS for CTP Bundles by Using Service Type Overview
In IP networks, the IP flow is typically classified based on the Differentiated Services Code Point (DSCP) setting in the type of service (TOS) byte of the IP header. DSCP is a scalable solution for classifying flows in a large IP network based on the class of service desired on specific IP traffic flows.
With the CTP device, you can configure DSCP settings for each circuit’s IP flow. For example, some circuits could be configured for the expedited forwarding (EF) class. When the network routers receive this EF-marked flow from the CTP device, they place the marked traffic into a high-priority queue, enabling this traffic to be serviced before lower priority traffic. As an EF-marked flow traverses the IP network, routers can use its classification to provide the flow a more predictable level of performance across the network
When you configure the service type of a bundle, you specify the ToS byte to be used in IP headers of packets sent from the CTP device to the IP network. The ToS setting is applied to circuits created by the bundle for which the service type is configured.
Table 1 shows the mapping for each DSCP class and setting to the ToS setting that you configure as the service type for a bundle. The EF class (ToS setting 184) is commonly used for circuit traffic.
Table 1: DSCP Classes and Service Type
| DSCP Class | DSCP Setting | ToS Setting |
|---|---|---|
CS7 | 56 | 224 |
CS6 | 48 | 192 |
EF | 46 | 184 |
CS5 | 40 | 160 |
AF43 | 38 | 152 |
AF42 | 36 | 144 |
AF41 | 34 | 136 |
CS4 | 32 | 128 |
AF33 | 30 | 120 |
AF32 | 28 | 112 |
AF31 | 26 | 104 |
CS3 | 24 | 96 |
AF23 | 22 | 88 |
AF22 | 20 | 80 |
AF21 | 18 | 72 |
CS2 | 16 | 64 |
AF13 | 13 | 52 |
AF12 | 12 | 48 |
AF11 | 10 | 40 |
CS1 | 8 | 32 |