ProCurve 2610-PWR Technical Information download pdf (Page 195)

Quality of Service (QoS): Managing Bandwidth More Effectively

Introduction

QoS is implemented in the form of rules or policies that are configured on the

switch. While you can use QoS to prioritize only the outbound traffic while it

is moving through the switch, you derive the maximum benefit by using QoS

in an 802.1Q VLAN environment (with 802.1p priority tags) or in an untagged

VLAN environment (with DSCP policies) where QoS can set priorities that

downstream devices can support without re-classifying the traffic.

By prioritizing traffic, QoS supports traffic growth on the network while

optimizing the use of existing resources—and delaying the need for further

investments in equipment and services. That is, QoS enables you to:

■ Specify which traffic has higher or lower priority, regardless of current

network bandwidth or the relative priority setting of the traffic when it is

received on the switch.

■ Change (upgrade or downgrade) the priority of outbound traffic.

■ Override “illegal” packet priorities set by upstream devices or applications

that use 802.1Q VLAN tagging with 802.1p priority tags.

■ Avoid or delay the need to add higher-cost NICs (network interface cards)

to implement prioritizing. (Instead, control priority through network

policy.)

QoS on the switches covered by this guide supports these types of traffic

marking:

■ 802.1p prioritization: Controls the outbound port queue priority for

traffic leaving the switch, and (if traffic exits through a VLAN-tagged port)

sends the priority setting with the individual packets to the downstream

devices.

■ IP Type-of-Service (ToS): Enables the switch to set, change, and honor

prioritization policies by using the Differentiated Services (diffserv) bits

in the ToS byte of IPv4 packet headers.

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ProCurve 2610-PWR Technical Information Page 195