Reference Guide

430 | Quality of Service (QoS)
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Apply an Output Policy Map to an Interface
To apply an output policy map to an interface, use the service-policy output command from INTERFACE
mode. You can apply the same policy map to multiple interfaces, and you can modify a policy map after
you apply it.
QoS Rate Adjustment
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)
By default, for rate policing and shaping, FTOS does not include the Preamble, SFD, or the IFG fields.
These fields are overhead; only the fields from MAC Destination Address to the CRC are used for
forwarding and are included in these rate metering calculations. You can optionally include overhead
fields in rate metering calculations by enabling QoS Rate Adjustment.
QoS rate adjustment is disabled by default with the
no qos-rate-adjust parameter listed in the
running-configuration.
Task Command Syntax Command Mode
Include a specified number of bytes of packet overhead
to include in rate policing and shaping calculations. For
example, to include the Preamble and SFD, enter
qos-rate-adjust 8.
For variable length overhead fields, you must know the
number of bytes you want to include.
qos-rate-adjust overhead-bytes
Default: Disabled
Range: 1-31
CONFIGURATION