ZyXEL Communications Corporation VSG1435B101 Manual De Usuario

Chapter 10 Quality of Service (QoS)

VSG1435-B101 Series User’s Guide

The following section contains additional technical information about the ZyXEL 
Device features described in this chapter.

The IEEE 802.1Q standard defines an explicit VLAN tag in the MAC header to 
identify the VLAN membership of a frame across bridges. A VLAN tag includes the 
12-bit VLAN ID and 3-bit user priority. The VLAN ID associates a frame with a 
specific VLAN and provides the information that devices need to process the frame 
across the network. 

IEEE 802.1p specifies the user priority field and defines up to eight separate traffic 
types. The following table describes the traffic types defined in the IEEE 802.1d 
standard (which incorporates the 802.1p).  

Pass Rate

This shows how many packets assigned to this queue are transmitted 
successfully.

Drop Rate

This shows how many packets assigned to this queue are dropped.

Table 37   Network Settings > QoS > Monitor (continued)

Table 38   IEEE 802.1p Priority Level and Traffic Type

Level 7

Typically used for network control traffic such as router configuration 
messages.

Level 6

Typically used for voice traffic that is especially sensitive to jitter (jitter is the 
variations in delay).

Level 5

Typically used for video that consumes high bandwidth and is sensitive to 
jitter.

Level 4

Typically used for controlled load, latency-sensitive traffic such as SNA 
(Systems Network Architecture) transactions.

Level 3

Typically used for “excellent effort” or better than best effort and would 
include important business traffic that can tolerate some delay.

Level 2

This is for “spare bandwidth”. 

Level 1

This is typically used for non-critical “background” traffic such as bulk 
transfers that are allowed but that should not affect other applications and 
users. 

Level 0

Typically used for best-effort traffic.