Reference Guide

Quality of Service | 813
The behavior is similar for trust dot1p fallback in a Layer2 input policy map; the dot1p-to-queue mapping
is according to Table 44-6, "Default dot1p to Queue Mapping," in Quality of Service.
To enable Fall Back to trust diffserve or dot1p:
Mapping dot1p values to service queues
Mapping dot1p values to service queues is available only on platforms: c s
On the C-Series and S-Series all traffic is by default mapped to the same queue, Queue 0. If you honor
dot1p on ingress, then you can create service classes based the queueing strategy in Table 44-6, "Default
dot1p to Queue Mapping," in Quality of Service using the command
service-class dynamic dot1p from
INTERFACE mode. You may apply this queuing strategy globally by entering this command from
CONFIGURATION mode.
• All dot1p traffic is mapped to Queue 0 unless
service-class dynamic dot1p is enabled on an interface
or globally.
• Layer 2 or Layer 3 service policies supersede dot1p service classes.
Guaranteeing bandwidth to dot1p-based service queues
Guarantee a minimum bandwidth to queues globally from CONFIGURATION mode with the command
service-class bandwidth-weight. The command is applied in the same way as the bandwidth-weight
command in an output QoS policy (refer to Allocate bandwidth to queue). The
bandwidth-weight command
in QOS-POLICY-OUT mode supersedes the
service-class bandwidth-weight command.
Apply an input policy map to an interface
Apply an input policy map to an interface using the command service-policy input from INTERFACE
mode. Specify the keyword
layer2 if the policy map you are applying a Layer 2 policy map; in this case,
the INTERFACE must be in switchport mode. You can apply the same policy map to multiple interfaces,
and you can modify a policy map after you apply it.
• You cannot apply a class-map and QoS policies to the same interface.
• You cannot apply an input Layer 2 QoS policy on an interface you also configure with
vlan-stack
access.
• If you apply a service policy that contains an ACL to more than one interface, FTOS uses ACL
optimization to conserves CAM space. The ACL Optimization behavior detects when an ACL already
exists in the CAM and rather than writing it to the CAM multiple times.
Task Command Syntax Command Mode
Classify packets according to their DSCP value as a secondary option in
case no match occurs against the configured class maps.
trust {diffserve |
dot1p} fallback
POLICY-MAP-IN