Dell Force10 S4820T S4820T Configuration Guide - Page 775

2. Once you create an output policy map, do one or more of the following: • Apply an output QoS policy to a queue • Specify an aggregate QoS policy • Apply an output policy map to an interface 3. Apply the policy map to an interface. See page 61. Apply an output QoS policy to a queue Apply an output QoS policy to queues using the command service-queue from INTERFACE mode. 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. Quality of Service (QoS) | 775