Planet WGSW-2840 [43/104] Security

4.7 Security

4.7.1 VLAN

4.7.1.1 Theory

Understanding IEEE 802.1p Priority

Priority tagging is a function defined by the IEEE 802.1p standard designed to provide a means of managing traffic

on a network where many different types of data may be transmitted simultaneously. It is intended to alleviate

problems associated with the delivery of time critical data over congested networks. The quality of applications

that are dependent on such time critical data, such as video conferencing, can be severely and adversely affected

by even very small delays in transmission.

Network devices that are in compliance with the IEEE 802.1p standard have the ability to recognize the priority

level of data packets. These devices can also assign a priority label or tag to packets. Compliant devices can also

strip priority tags from packets. This priority tag determines the packet's degree of expeditiousness and

determines the queue to which it will be assigned.

Priority tags are given values from 0 to 7 with 0 being assigned to the lowest priority data and 7 assigned to the

highest. The highest priority tag 7 is generally only used for data associated with video or audio applications,

which are sensitive to even slight delays, or for data from specified end users whose data transmissions warrant

special consideration.

The Switch allows you to further tailor how priority tagged data packets are handled on your network. Using

queues to manage priority tagged data allows you to specify its relative priority to suit the needs of your network.

There may be circumstances where it would be advantageous to group two or more differently tagged packets into