Dell Force10 S4810P Configuration Manual page 833

When using QoS service policies with multiple class maps, you can configure FTOS to use the incoming
DSCP or dot1p marking as a secondary option for packet queuing in the event that no match occurs in the
class maps.
When class-maps are used, traffic is matched against each class-map sequentially from first 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 configuration,
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 configuration, packets are classified to queues using the three class maps:
!
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
!
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 classification logic for the above configuration 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.
You can optionally classify packets using their DSCP marking, instead of placing packets in Queue 0, if no
match occurs. In the above example, if no match occurs against match-all qos-BE1, the classification logic
continues:
4. Queue the packet according to the DSCP marking. The DSCP to Queue mapping will be as per the
Table 39-5.
The behavior is similar for
according to Table 39-6.
in a Layer2 input policy map; the dot1p-to-queue mapping is
trust dot1p fallback
Quality of Service (QoS) | 833