ZyXEL Communications P-660HN-F1A, User Manual

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Chapter 16 Quality of Service (QoS)
P-660HN-F1A User’s Guide
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The following table describes the labels in this screen.
16.10 QoS Technical Reference
This section provides some technical background information about the topics
covered in this chapter.
16.10.1 IEEE 802.1Q Tag
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).
Table 80 Advanced > QoS > Monitor
LABEL DESCRIPTION
Priority Queue This shows the priority queue number.
Traffic assigned to higher index queues gets through faster while
traffic in lower index queues is dropped if the network is congested.
Pass This shows how many packets mapped to this priority queue are
transmitted successfully.
Drop This shows how many packets mapped to this priority queue are
dropped.
Poll Interval(s) Enter the time interval for refreshing statistics in this field.
Set Interval Click this to apply the new poll interval you entered in the Poll
Interval(s) field.
Stop Click this to stop refreshing statistics.
Table 81 IEEE 802.1p Priority Level and Traffic Type
PRIORITY
LEVEL
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.