Users Guide

Applying an Output Policy Map to an Interface
To apply an output policy map to an interface, use the following command.
• Apply an input policy map to an interface.
INTERFACE mode
service-policy output
You can apply the same policy map to multiple interfaces, and you can modify a policy map after you apply it.
Enabling QoS Rate Adjustment
By default while rate limiting, policing, and shaping, Dell Networking OS does not include the Preamble, SFD, or the IFG elds. These elds
are overhead; only the elds from MAC destination address to the CRC are used for forwarding and are included in these rate metering
calculations.
The Ethernet packet format consists of:
• Preamble: 7 bytes Preamble
• Start frame delimiter (SFD): 1 byte
• Destination MAC address: 6 bytes
• Source MAC address: 6 bytes
• Ethernet Type/Length: 2 bytes
• Payload: (variable)
• Cyclic redundancy check (CRC): 4 bytes
• Inter-frame gap (IFG): (variable)
You can optionally include overhead elds in rate metering calculations by enabling QoS rate adjustment.
QoS rate adjustment is disabled by default.
• Specify the number of bytes of packet overhead to include in rate limiting, policing, and shaping calculations.
CONFIGURATION mode
qos-rate-adjust overhead-bytes
For example, to include the Preamble and SFD, type qos-rate-adjust 8. For variable length overhead elds, know the number of
bytes you want to include.
The default is disabled.
Enabling Strict-Priority Queueing
In strict-priority queuing, the system de-queues all packets from the assigned queue before servicing any other queues. You can assign
strict-priority to one unicast queue, using the strict-priority command.
• Policy-based per-queue rate shaping is not supported on the queue congured for strict-priority queuing. To use queue-based rate-
shaping as well as strict-priority queuing at the same time on a queue, use the Scheduler Strict feature as described in Scheduler
Strict .
• The strict-priority supersedes bandwidth-percentage conguration.
• A queue with strict priority can starve other queues in the same port-pipe.
• Assign strict priority to one unicast queue.
CONFIGURATION mode
strict-priority
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Quality of Service (QoS)