Dell FCX624-I Laptop User Manual


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PowerConnect B-Series FCX Configuration Guide 591
53-1002266-01
Chapter
17
Configuring Quality of Service
Table 93 lists the individual Dell PowerConnect switches and the Quality of Service (QoS) features
they support.
8802.1
Classification
Quality of Service (QoS) features are used to prioritize the use of bandwidth in a switch. When QoS
features are enabled, traffic is classified as it arrives at the switch, and processed through on the
basis of configured priorities. Traffic can be dropped, prioritized for guaranteed delivery, or subject
to limited delivery options as configured by a number of different mechanisms.
This chapter describes how QoS is implemented and configured in PowerConnect devices.
Classification is the process of selecting packets on which to perform QoS, reading the QoS
information and assigning a priority to the packets. The classification process assigns a priority to
packets as they enter the switch. These priorities can be determined on the basis of information
contained within the packet or assigned to the packet as it arrives at the switch. Once a packet or
traffic flow is classified, it is mapped to a forwarding priority queue.
Packets on Dell PowerConnect devices are classified in up to eight traffic classes with values
between 0 and 7. Packets with higher priority classifications are given a precedence for forwarding.
Processing of classified traffic
The trust level in effect on an interface determines the type of QoS information the device uses for
performing QoS. The Dell PowerConnect device establishes the trust level based on the
configuration of various features and whether the traffic is switched or routed. The trust level can
be one of the following:
Ingress port default priority
TABLE 93 Supported QoS features
Feature PowerConnect B-Series FCX
802.1p Quality of Service (QoS):
Strict Priority (SP)
Weighted Round Robin (WRR)
Combined SP and WRR
8 priority queues
Yes
802.1p priority override Yes
802.1p marking Yes
DiffServ support Yes
DSCP-based QoS Yes
QoS mappings Yes