System information

Configuring the Switch
3-100
Setting the Service Weight for Traffic Classes
This switch uses the Weighted Round Robin (WRR) algorithm to determine the
frequency at which it services each priority queue. As described in “Mapping CoS
Values to Egress Queues” on page 3-97, the traffic classes are mapped to one of the
four egress queues provided for each port. You can assign a weight to each of these
queues (and thereby to the corresponding traffic priorities). This weight sets the
frequency at which each queue will be polled for service, and subsequently affects
the response time for software applications assigned a specific priority value.
Command Attributes
•
WRR Setting Table* – Displays a list of weights for each traffic class
(i.e., queue).
•
Weight Value – Set a new weight for the selected traffic class. (Range: 1-255)
* CLI shows Queue ID.
Web – Click Priority, Queue Scheduling. Select the interface, highlight a traffic class
(i.e., output queue), enter a weight, then click Apply.
CLI – The following example shows how to assign WRR weights to each of the
priority queues.
Mapping Layer 3/4 Priorities to CoS Values
This 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 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.
Console(config)#queue bandwidth 2 8 16 128 4-147
Console(config)#exit
Console#show queue bandwidth 4-149
Queue ID Weight
-------- ------
0 2
1 8
2 16
3 128
Console#