Traffic Classification - 3Com 3824 Implementation Manual

Traffic Classification

Traffic prioritization in your Switch may be applied dependent upon
following factor:
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.
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 quality of service the Switch will use four 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.
Traffic Re-marking — if a traffic packet enters the Switch with a
priority marking requesting an unacceptable level of service, the
Switch can Re-mark it with a different priority value to downgrade its
level of service.
Traffic Prioritization — once the network can differentiate types of
traffic, for example, a telephone conversation from Web surfing,
prioritization can ensure that a large download from the Internet does
not disrupt the telephone conversation.
The Switch is configured to handle priority tagged packets and NBX
phone traffic.
To determine the service level to be applied to each incoming traffic type,
each packet or frame must first be classified. Traffic classification is the
means of identifying which application, device or user generated the
traffic.
The Switch employs several methods of classifying (identifying) traffic.
These can be based on any combination of fields in the first 64 bytes of
the packet, and at different levels of the 7 layer OSI model as shown in
Table 5.
How Traffic Prioritization Works 49