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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