HP Network Direr Software Products manual User Priority

652CHAPTER 15: PRIORITIZING NETWORK TRAFFIC

Useful Information The following section provides useful information and references when

and References using 3Com Network Director.

User Priority Field The user priority field (and the tagged header that it is present in) allows information about the priority level of a packet to be carried with the packet as it traverses the network. The field is defined within the IEEE (Institute of Electrical and Electronics Engineers) 802.1D standard, which is available from the IEEE website:

http://www.ieee.org/

This standard defines the use of the eight values that the field may take.

These definitions are shown in Table 101.

Table 101 User Priority

User Priority	Use
1	Background
2	Spare
0 (Default)	Best Effort
3	Excellent Effort
4	Controlled Load
5	“Video,” < 100 ms latency and jitter
6	“Voice,” < 10 ms latency and jitter
7	Network Control

As the table shows, the default value is 0. This allows some traffic to be marked as less important than normal traffic.

The tagged header that the user priority field relies upon can be used in any packet in place of the normal 802.1D header. However, the tagged header is only normally used for packets if VLANs are being used within the network. This means that if VLANs are not being used then the information about the importance of traffic cannot be conveyed from a complex classification device to a simple classification device using this marking mechanism. See “Vlan Management” on page 623 for more information on configuring VLANs using 3Com Network Director.