ZyXEL Communications AMG1202-T10A, User Manual

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Chapter 14 Quality of Service (QoS)
AMG1202-T10A User’s Guide
164
14.3 QoS Technical Reference
This section provides some technical background information about the topics covered in this
chapter.
14.3.1 IEEE 802.1p
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).
14.3.2 IP Precedence
Similar to IEEE 802.1p prioritization at layer-2, you can use IP precedence to prioritize packets in a
layer-3 network. IP precedence uses three bits of the eight-bit ToS (Type of Service) field in the IP
header. There are eight classes of services (ranging from zero to seven) in IP precedence. Zero is
the lowest priority level and seven is the highest.
14.3.3 Automatic Priority Queue Assignment
If you enable QoS on the ZyXEL Device, the ZyXEL Device can automatically base on the IEEE
802.1p priority level, IP precedence and/or packet length to assign priority to traffic which does not
match a class.
802.1p Remarking The ZyXEL Device re-assigns the priority levels specified in this field to
matched traffic.
Queue # The ZyXEL Device assigns the queue level specified in this field to matched
traffic.
Table 59
Advanced Setup > QoS > QoS Settings Summary (continued)
LABEL DESCRIPTION
Table 60
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.
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.