Cisco Catalyst 2950 Software Guide

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Catalyst 2950 Desktop Switch Software Configuration Guide
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Chapter 13 Configuring QoS
Configuring QoS
Configuration Guidelines
Note These guidelines are applicable only if your switch is running the enhanced software image.
Before beginning the QoS configuration, you should be aware of this information:
• If you have EtherChannel ports configured on your switch, you must configure QoS classification,
policing, mapping, and queueing on the individual physical ports that comprise the EtherChannel.
You must decide whether the QoS configuration should match on all ports in the EtherChannel.
• It is not possible to match IP fragments against configured IP extended ACLs to enforce QoS. IP
fragments are transmitted as best-effort. IP fragments are denoted by fields in the IP header.
• Control traffic (such as spanning-tree Bridge Protocol Data Units (BPDUs) and routing update
packets) received by the switch are subject to all ingress QoS processing.
• Only one ACL per class map and only one match command per class map are supported. The ACL
can have multiple access control entries, which are commands that match fields against the contents
of the packet.
• Policy maps with ACL classification in the egress direction are not supported and cannot be attached
to an interface by using the service-policy input policy-map-name interface configuration
command.
• In a policy map, the class named class-default is not supported. The switch does not filter traffic
based on the policy map defined by the class class-default policy-map configuration command.
• For more information on guidelines for configuring ACLs, see the “Classification Based on QoS
ACLs” sectiononpage13-5.
Configuring Classification Using Port Trust States
This section describes how to classify incoming traffic by using port trust states:
• Configuring the Trust State on Ports within the QoS Domain, page 13-11
• Configuring the CoS Value for an Interface, page 13-13
The default CoS-to-DSCP map is shown inTable 13-3.
1
The default DSCP-to-CoS map is shown in Table 13-4.
1
For default QoS and WRR values, see the “Configuring CoS and WRR” section on page 13-23.
1. Available only on a switch running the enhanced software image.
Table 13-2 Default QoS Configuration (continued)
The default port CoS value is 0.

Cisco Catalyst 2950 Specifications

General

Forwarding Bandwidth	8.8 Gbps
Switching Capacity	13.6 Gbps
Forwarding Rate	6.6 Mpps
Weight	3.6 kg
RAM	16 MB
Flash Memory	8 MB
Operating Humidity	10% to 85% non-condensing
Uplink Ports	2 x 10/100/1000Base-T
Dimensions	4.4 cm x 44.5 cm x 24.2 cm
Remote Management Protocol	SNMP, Telnet, HTTP
Features	Quality of Service (QoS), VLAN support
Compliant Standards	IEEE 802.3, IEEE 802.3u, IEEE 802.1D, IEEE 802.1Q, IEEE 802.1p
Status Indicators	system
Operating Temperature	0 to 45°C
Ports	24 x 10/100 Ethernet ports
MAC Address Table Size	8, 192 entries
Power Supply	Internal 100-240V AC, 50-60Hz