Dell S50V Switch User Manual


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Quality of Service | 869
Specify an aggregate QoS policy
Specify an aggregate QoS policy using the command policy-aggregate from POLICY-MAP-OUT mode.
Apply an output policy map to an interface
Apply an input policy map to an interface using the command service-policy output 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, while rate limiting, 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, and no
qos-rate-adjust is listed in the running-configuration.
Task Command Syntax Command Mode
Include a specified number of bytes of packet overhead
to include in rate limiting, 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
C-Series and S-Series Range: 1-31
E-Series Range: 1-144
CONFIGURATION