8.1.6. qos trust

Syntax

qos trust (cos | cos-dscp | dscp | precedence)

Parameter

cos Specify the device to trust CoS

cos-dscp Specify the device to trust DSCP for IP packets, and trust CoS for non-IP packets.

dscp Specify the device to trust DSCP

precedence Specify the device to trust IP Precedence

Default

Default QoS trust type is cos.

Mode

Global Configuration

Usage

In QoS basic mode, there are 4 trust types for device to judge the appropriate queue of the packets. This command is able to switch between these trust types.

CoS:

IEEE 802.1p defined 3bits priority value in vlan tag. Trust this value in packets and assign queue according to cos-queue map.

DSCP:

IETF RFC2474 defined 6bits priority value in IP packet (highest 6bits in ToS field). Trust this value in packets and assign queue according to dscp-queue map.

IP Precedence:

The highest 3bits priority value in IP packet ToS field. Trust this value in packets and assign queue according to precedence-queue map.

CoS-DSCP:

Trust DSCP for IP packets and assign queue according to dscp-queue map. Trust CoS for non-IP packets and assign queue according to cos-queue map.

Example

This example shows how to change qos basic mode trust types.

Switch(config)# qos trust cos
Switch(config)# qos trust cos-dscp
Switch(config)# qos trust dscp
Switch(config)# qos trust precedence

This example shows how to check current qos trust type.

Switch# show qos
QoS Mode: basic
Basic trust: ip-precedence