AMX NXA-ENET8-POE+, Instruction Manual, Page: 121 / 283

Class of Service
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Instruction Manual - NXA-ENET8-POE+
Layer 3/4 Priority Settings
The switch supports several common methods of prioritizing layer 3/4 traffic to meet application requirements. Traffic priorities
can be specified in the IP header of a frame, using the priority bits in the Type of Service (ToS) octet, or the number of the TCP/
UDP port. If priority bits are used, the ToS octet may contain three bits for IP Precedence or six bits for Differentiated Services Code
Point (DSCP) service.
When these services are enabled, the priorities are mapped to a Class of Service value by the switch, and the traffic then sent to the
corresponding output queue.
Because different priority information may be contained in the traffic, this switch maps priority values to the output queues in the
following manner - The precedence for priority mapping is DSCP Priority and then Default Port Priority.
NOTE: The default settings used for mapping priority values from ingress traffic to internal DSCP values are used to determine the
hardware queues used for egress traffic, not to replace the priority values. These defaults are designed to optimize priority services
for the majority of network applications. It should not be necessary to modify any of the default settings, unless a queuing problem
occurs with a particular application.
Setting Priority Processing to DSCP or CoS
The switch allows a choice between using DSCP or CoS priority processing methods. Use the Priority > Trust Mode page to select
the required processing method.
Command Usage

If the QoS mapping mode is set to DSCP, and the ingress packet type is IPv4, then priority processing will be based on the
DSCP value in the ingress packet.

If the QoS mapping mode is set to DSCP, and a non-IP packet is received, the packet's CoS and CFI (Canonical Format
Indicator) values are used for priority processing if the packet is tagged. For an untagged packet, the default port priority
(see the Setting the Default Priority for Interfaces section on page 119) is used for priority processing.

If the QoS mapping mode is set to CoS, and the ingress packet type is IPv4, then priority processing will be based on the
CoS and CFI values in the ingress packet.
For an untagged packet, the default port priority (see the
Setting the Default Priority for Interfaces section on page 119) is
used for priority processing.
The following table lists the options on this page:
FIG. 133
Setting the Queue Mode (WRR)
FIG. 134
Setting the Queue Mode (Strict and WRR)
Traffic - Priority (Trust Mode) Options
Port Port identifier. (Range: 1-10/28)
Trust Mode • CoS - Maps layer 3/4 priorities using Class of Service values. (This is the default setting.)
• DSCP - Maps layer 3/4 priorities using Differentiated Services Code Point values.