Deployment Guide

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.
5 Queue the packet according to the DSCP marking. The DSCP to Queue mapping is as noted in Honoring dot1p Values on Ingress
Packets.
The behavior is similar for trust dot1p fallback in a Layer2 input policy map; the dot1p-to-queue mapping is noted in Honoring
dot1p Values on Ingress Packets.
To enable fall back to trust diserve or dot1p, use the following command.
• Classify packets according to their DSCP value as a secondary option in case no match occurs against the congured class maps.
POLICY-MAP-IN mode
trust {diffserve | dot1p} fallback
Mapping dot1p Values to Service Queues
All trac is by default mapped to the same queue, Queue 0.
If you honor dot1p on ingress, you can create service classes based the queueing strategy in Honoring dot1p Values on Ingress Packets. You
may apply this queuing strategy globally by entering the following command from CONFIGURATION mode.
• All dot1p trac is mapped to Queue 0 unless you enable service-class dynamic dot1p on an interface or globally.
• Layer 2 or Layer 3 service policies supersede dot1p service classes.
• Create service classes.
INTERFACE mode
service-class dynamic dot1p
Guaranteeing Bandwidth to dot1p-Based Service Queues
To guarantee bandwidth to dot1p-based service queues, use the following command.
Apply this command in the same way as the bandwidth-percentage command in an output QoS policy (refer to Allocating Bandwidth
to Queue
). The bandwidth-percentage command in QOS-POLICY-OUT mode supersedes the service-class bandwidth-
percentage command.
• Guarantee a minimum bandwidth to queues globally.
CONFIGURATION mode
service-class bandwidth-percentage
Applying an Input Policy Map to an Interface
To apply an input policy map to an interface, use the following command.
You can apply the same policy map to multiple interfaces, and you can modify a policy map after you apply it.
• You cannot apply an input Layer 2 QoS policy on an interface you also congure with the vlan-stack access command.
• If you apply a service policy that contains an ACL to more than one interface, the system uses ACL optimization to conserve CAM
space. The ACL optimization behavior detects when an ACL exists in the CAM rather than writing it to the CAM multiple times.
Quality of Service (QoS)
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