Web Management Guide-R04

Table Of Contents
Chapter 9
| Class of Service
Layer 3/4 Priority Settings
– 264 –
Mapping IP
Precedence Values to
Internal DSCP Values
Use the Traffic > Priority > IP Precedence to DSCP page to map IP precedence
values in incoming packets to per-hop behavior and drop precedence values for
priority processing.
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 map one-to-one to the Class of Service values (that is, Precedence value 0
maps to PHB value 0, and so forth). Bits 6 and 7 are used for network control, and
the other bits for various application types. The ToS bits are defined in Table 19.
Command Usage
Enter per-hop behavior and drop precedence for any of the IP Precedence
values 0 - 7.
If the priority mapping mode is set the IP Precedence and the ingress packet
type is IPv4, then the IP Precedence-to-PHB/Drop Precedence mapping table is
used to generate priority and drop precedence values for internal processing.
Parameters
These parameters are displayed in the web interface:
Port – Port identifier.
IP Precedence – IP Precedence value in ingress packets. (Range: 0-7)
PHB – Per-hop behavior, or the priority used for this router hop. (Range: 0-7)
Table 19: Mapping IP Precedence
Priority Level Traffic Type
7Network Control
6 Internetwork Control
5Critical
4Flash Override
3Flash
2 Immediate
1Priority
0Routine