Qos Pass-Through Mode; General Operation - HP ProCurve 2810 Series Management And Configuration Manual

QoS Pass-Through Mode

QoS Pass-Through mode is designed to enhance the performance of line-rate
traffic transfers through the switches covered in this guide. This feature
should only be used in environments where Quality of Service (QoS) is not of
major importance, but where lossless data transfers are key. This command
disables any discrimination of QoS queues for traffic, consolidating packet
buffer memory to provide line-rate flows with no loss of data.

General Operation

The port buffering design for the switch has been optimized for gigabit-to­
gigabit traffic flows. For this reason, some flows from Gigabit-to-100Base or
even 100Base-to-10Base may not perform as well as would be expected. The
QoS Pass-Through mode enhancement can provide a significant performance
improvement for high-bandwidth traffic flows through the switch, particularly
when running traffic flows from 1000Base to either 100Base or 10Base connec­
tions.
QoS Pass-Through mode is enabled by default. If it has been disabled, you can
re-enable it via the "config" context of the CLI by entering the CLI command
qos-passthrough-mode, followed by write memory and rebooting the switch.
QoS Pass-Through mode, when enabled, results in the following general
changes to switch operation:
■ Alters the switch's default outbound priority queue scheme from four
queues (low, normal, medium, and high), to two queues (normal &
high).
■ Optimizes outbound port buffers for a two-queue scheme.
All packets received with an 802.1p priority tag of 0 to 5 (low, normal,
■
or medium priorities), or tagged by the switch's QOS feature, will be
serviced by the (now larger) "normal" priority queue.
All packets received with an 802.1p priority tag of 6 or 7 (high priority),
■
or tagged by the switch's QoS feature, will be serviced by the "high"
priority queue.
High priority packets sourced by the switch itself, such as Spanning
■
Tree packets, will be serviced in the "high" priority queue.
Port Status and Basic Configuration
QoS Pass-Through Mode
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