HP 5400ZL - Manual (Page 226)

Quality of Service: Managing Bandwidth More Effectively
Using Quality of Service Policies
Using Quality of Service Policies
A Quality of Service (QoS) network policy refers to the network-wide controls
you can implement to:
■ Ensure uniform and efficient traffic-handling throughout your network,
while keeping the most important traffic moving at an acceptable speed,
regardless of current bandwidth usage.
■ Exercise control over the priority settings of inbound traffic arriving in
and travelling through your network.
Adding bandwidth is often a good idea, but it is not always feasible and does
not completely eliminate the potential for network congestion. There will
always be points in the network where multiple traffic streams merge or where
network links change speed and capacity. The impact and number of these
congestion points will increase over time as more applications and devices
are added to the network.
When (not if) network congestion occurs, it is important to move traffic on
the basis of relative importance. However, without Quality of Service (QoS)
prioritization, less important traffic can consume network bandwidth and
slow down or halt the delivery of more important traffic. That is, without QoS,
most traffic received by the switch is forwarded with the same priority it had
upon entering the switch. In many cases, such traffic is “normal” priority and
competes for bandwidth with all other normal-priority traffic, regardless of
its relative importance to your organization’s mission.
Use QoS to classify and prioritize network traffic. Quality of Service is
used to classify and prioritize traffic throughout a network. QoS enables you
to establish an end-to-end traffic-priority policy to improve the control and
throughput of important data. You can manage available bandwidth so that
the most important traffic goes first. For example, you can use Quality of
Service to:
■ Upgrade or downgrade traffic from various servers.
■ Control the priority of traffic from dedicated VLANs or applications.
■ Change the priorities of traffic from various segments of your network as
your business needs change.
■ Set priority policies in edge switches in your network to enable traffic-
handling rules across the network.
6-4