3Com 3C17203 - SuperStack 3 Switch 4400, Implementation Manual

Page: 63 / 153

How Traffic Prioritization Works 63
For a look at a 3Com white paper on how to gain control of the network,
please refer to the PDF format article at this link:
http://www.3com.com/other/pdfs/products/en_US/getcontrolofth
enetwork.pdf
(correct at time of publication)
How Traffic
Prioritization Works
Traffic prioritization uses the four traffic queues that are present in your
Switch to ensure that high priority traffic is forwarded on a different
queue from lower priority traffic. This is what provides Quality of Service
(QoS) to your network.
Traffic prioritization in your Switch may be applied dependent upon two
factors:
■
The level of service requested by an end-station — the
transmitting end-station sets the priority of each stream of traffic.
Received traffic at the Switch is forwarded through the appropriate
queue depending on its priority level for onward transmission across
the network.
or
■
The level of service configured at the Switch for incoming
traffic
— the network administrator configures the Switch to
prioritize or discard traffic from applications or devices. For example,
converged network applications such as voice or video conferencing
or business critical software such as Oracle may require a high level of
service from the network.
A QoS network can differentiate between time critical data, business
critical data and opportunistic data (such as email, File Transfer Protocol
(FTP) and Web traffic). A QoS network also has the ability to stop
unauthorized usage of the network, such as online gaming.
To achieve this level of intelligence, a QoS network incorporates five
processes:
■
Traffic Classification — a QoS network examines the traffic to
identify which application or device generated the traffic.
■
Traffic Marking — after traffic is identified, it is Marked so that other
network devices can identify the data and give it the correct level of
service.