HP 3500 Series Advanced Traffic Management Manual page 221

Preserve QoS in outbound traffic in a VLAN. QoS is implemented in the
form of rules or policies that are configured on the switch. Although you can
use QoS to prioritize traffic only while it moves 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
in which QoS sets priorities that downstream devices can support without re-
classifying the traffic).
Use QoS to optimize existing network resources. By prioritizing traf-
fic, QoS supports traffic growth on the network while optimizing the use of
existing resources—and delaying the need for further investments in equip-
ment and services. 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.
Use classifier-based QoS to provide additional policy actions and aid
migration in networks with legacy and OEM devices.
Starting in software release K.14.01, HP QoS configuration supports a classi-
fier-based model that provides added functionality to create and manage QoS
policies across a network consisting of HP switches as well as OEM and legacy
devices.
The classifier-based configuration model is a single, simplified procedure and
command syntax for cross-feature usage, which offers:
Finer granularity than globally-configured QoS for classifying IPv4 and
■
IPv6 traffic
■ Additional actions for managing selected traffic, such as rate-limiting and
IP precedence marking
The application of QoS policies to inbound traffic flows on specific port
■
and VLAN interfaces (instead of using only globally-configured, switch-
wide QoS settings)
■ The use of configured traffic classes by different software features, such
as QoS or port mirroring
Classifier-based QoS is designed to work with existing globally-configured,
switch-wide QoS policies by allowing you to zoom in on a subset of port or
VLAN traffic to further manage it. Classifier-based policies take precedence
over and may override globally-configured, switch-wide QoS settings.
Quality of Service: Managing Bandwidth More Effectively
Using Quality of Service Policies
5-3