3 Configuring the Switch

Mapping IP Precedence

The Type of Service (ToS) octet in the IPv4 header includes three precedence bits defining eight different priority levels ranging from highest priority for network control packets to lowest priority for routine traffic. The default IP Precedence values are mapped one-to-one to Class of Service values (i.e., Precedence value 0 maps to CoS value 0, and so forth). Bits 6 and 7 are used for network control, and the other bits for various application types. ToS bits are defined in the following table.

Table 3-14 Mapping IP Precedence

Priority Level

Traffic Type

Priority Level

Traffic Type

 

 

 

 

7

Network Control

3

Flash

 

 

 

 

6

Internetwork Control

2

Immediate

 

 

 

 

5

Critical

1

Priority

 

 

 

 

4

Flash Override

0

Routine

 

 

 

 

Command Attributes

•IP Precedence Priority Table – Shows the IP Precedence to CoS map.

•Class of Service Value – Maps a CoS value to the selected IP Precedence value. Note that “0” represents low priority and “7” represent high priority.

Web – Click Priority, IP Precedence Priority. Select an entry from the IP Precedence Priority Table, enter a value in the Class of Service Value field, and then click Apply.

Figure 3-90 IP Precedence Priority

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