Administrator Guide

dot1p Queue ID
4 2
5 3
6 3
7 3
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
Enabling Fall Back to Trust Diserve or dot1p
When using QoS service policies with multiple class maps, you can congure the Dell Networking OS to use the incoming DSCP or
dot1p marking as a secondary option for packet queuing if no match occurs in the class maps.
When you use class-maps, trac is matched against each class-map sequentially from rst to last. The sequence is based on the
priority of the rules, as follows:
1. Rules with lowest priority, or in the absence of a priority conguration.
2. Rules of the next numerically higher queue.
By default, if no match occurs, the packet is queued to the default queue, Queue 0.
In the following conguration, packets are classied to queues using three class maps:
Example of Viewing Packet Classes Based on DSCP Value
!
policy-map-input input-policy
service-queue 1 class-map qos-BE1
service-queue 3 class-map qos-AF3
service-queue 4 class-map qos-AF4
trust diffserv fallback
!
class-map match-any qos-AF3
match ip dscp 24
match ip access-group qos-AF3-ACL
!
class-map match-any qos-AF4
match ip dscp 32
match ip access-group qos-AF4-ACL
!
class-map match-all qos-BE1
match ip dscp 0
match ip access-group qos-BE1-ACL
The packet classication logic for the conguration shown is as follows:
1. Match packets against match-any qos-AF4. If a match exists, queue the packet as AF4 in Queue 4, and if no match exists,
go to the next class map.
2. Match packets against match-any qos-AF3. If a match exists, queue the packet as AF3 in Queue 3, and if no match exists,
go to the next class map.
3. Match packets against match-all qos-BE1. If a match exists, queue the packet as BE1, and if no match exists, queue the
packets to the default queue, Queue 0.
4. You can optionally classify packets using their DSCP marking, instead of placing packets in Queue 0, if no match occurs. In the
above conguration, if no match occurs against match-all qos-BE1, the classication logic continues.
Quality of Service (QoS)
643