Extreme Networks ExtremeWare 7.7, Command Reference Manual

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ExtremeWare 7.7 Command Reference Guide 431
7
QoS Commands
This chapter describes the following commands:
• Commands for configuring Quality of Service (QoS) profiles
• Commands creating traffic groupings and assigning the groups to QoS profiles
• Commands for configuring, enabling and disabling explicit class-of-service traffic groupings (802.1p
and DiffServ)
• Commands for configuring, enabling and disabling Random Early Detection (RED) (supported only
on “
i ” series switches)
• Commands for configuring traffic grouping priorities
• Commands for verifying configuration and performance
• Commands for enabling and disabling the Dynamic Link Context System (DLCS) (supported only on
“
i ” series switches)
This chapter does not describe the additional ingress and egress QoS capabilities available on the High
Density Gigabit Ethernet
“3”
series I/O modules for “i” series switches. For more information and a full
description of the
“3”
series I/O module command set, see Chapter 29.
Qualify of Service (QoS) is a feature of ExtremeWare that allows you to specify different service levels
for outbound and inbound traffic. QoS is an effective control mechanism for networks that have
heterogeneous traffic patterns. Using QoS, you can specify the service that a traffic type receives.
Policy-based QoS allows you to protect bandwidth for important categories of applications or
specifically limit the bandwidth associated with less critical traffic. The switch contains separate
hardware queues on every physical port. Each hardware queue is programmed by ExtremeWare with
bandwidth management and priority parameters, defined as a QoS profile. The bandwidth management
and priority parameters that modify the forwarding behavior of the switch affect how the switch
transmits traffic for a given hardware queue on a physical port. Up to eight physical queues per port
are available.
Policy-based QoS can be configured on the “ i ” series switches to perform per-port Random Early
Detection (RED). Using this capability, the switch detects when traffic is filling up in any of the eight
hardware queues, and performs a random discard on subsequent packets, based on the configured RED
drop-probability. Instead of dropping sessions during times when the queue depth is exceeded, RED
causes the switch to lower session throughput.