3Com 4007, Руководство по внедрению, Страница: 201 / 684

Key Concepts 201
Key Concepts
Before you configure CoS options in a Layer 2 Switching Module, review
the following key concepts.
Basic Elements of
the Standard
The two basic elements of the IEEE 802.1p standard are:
■
Multiple processing queues in devices
The standard does not require a specific number of queues but rather
how different types of traffic could be allocated across up to eight
queues.
■
Priority levels carried in packets
Packets that include priority levels are processed through the device
queues in a way that is configured by the network administrator. The
standard identifies eight different priority levels using numbers 0
through 7.
Table 43 outlines the different types of traffic that the standards body
envisioned carrying different priority levels. However, you can apply
the eight numbers however you want to identify your network
application traffic.
Table 43 Priority Levels and Traffic Types Envisioned by Standards Committee
Priority Level Traffic Type
1 Background
2 (Spare)
0 (default) Best Effort
3 Excellent Effort
4 Controlled Load
5 Video, less than 100 milliseconds latency and jitter
6 Voice, less than 10 milliseconds latency and jitter
7 Network Control