L
AYER
3/4 P
RIORITY
S
ETTINGS
14-11
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 variou s
application types. ToS bits are defined in the following table.
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.
Table 14-3 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
4Flash Override0Routine