Administrator Guide

Honoring DSCP Values on Ingress Packets
You can configure the ability to honor DSCP values on ingress packets by using the Trust DSCP feature.
The following table lists the standard DSCP definitions and indicates how DSCP values are mapped to queues. When you
configure trust DSCP, the matched packets and matched bytes counters are not incremented in the show qos statistics.
Table 79. Default DSCP to Queue Mapping
DSCP/CP bit range (in
hexadecimal)
DSCP Definition Traditional IP
Precedence
Internal Queue ID DSCP/CP decimal
range
111xxx Network Control 7 56–63
110xxx Internetwork Control 6 48–55
101xxx EF (Expedited
Forwarding)
CRITIC/ECP 5 40–47
100xxx AF4 (Assured
Forwarding)
Flash Override 4 32–39
011xxx AF3 Flash 3 24–31
010xxx AF2 Immediate 2 16–23
001xxx AF1 Priority 1 8–15
000xxx BE (Best Effort) Best Effort 0 0–7
● Enable the trust DSCP feature.
POLICY-MAP-IN mode
trust diffserv
Honoring dot1p Values on Ingress Packets
In an input QoS policy, you can configure the system to honor dot1p values on ingress packets using the Trust dot1p feature.
The following table specifies the queue to which the classified traffic is sent based on the dot1p value.
Table 80. Default dot1p to Queue Mapping
Packet dot1p on Ingress Packet Queue ID
0 1
1 0
2 2
3 3
4 4
5 5
6 6
7 7
The dot1p value is also honored for frames on the default VLAN. For more information, refer to Priority-Tagged Frames on the
Default VLAN.
● Enable the trust dot1p feature.
POLICY-MAP-IN mode
trust dot1p
Quality of Service (QoS)
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