Enterprise QoS Solution Reference Network Design Guide

Chapter 2 Campus QoS Design
Catalyst 2950—QoS Considerations and Design
Version 3.3
This section includes the following topics:
Catalyst 2950—Trusted Endpoint Model
Catalyst 2950—AutoQoS VoIP Model
Catalyst 2950—QoS Considerations and Design
Catalyst 2950—Untrusted PC + SoftPhone with Scavenger-Class QoS Model
Catalyst 2950—Untrusted Server with Scavenger-Class QoS Model
Catalyst 2950—Conditionally-Trusted IP Phone + PC with Scavenger-Class QoS (Basic) Model
Catalyst 2950—Conditionally-Trusted IP Phone + PC with Scavenger-Class QoS (Advanced)
Model
Catalyst 2950—Queuing
The Catalyst 2950 does not support Layer 3 forwarding, and as such is only applicable as a low-end
access layer switch. The QoS design options for a Catalyst 2950 are shown in Figure 2-10.
Figure 2-10 Access Layer Catalyst 2950 QoS Design Options
Cisco recommends using the Enhanced Image (EI) versions of IOS software on these platforms because
these offer additional QoS features such as MQC/ACL classification options, policing and markdown
functions, mapping tables and AutoQoS.
Catalyst 2950—Trusted Endpoint Model
Configuration
Access-Edges
Trusted-Endpoint
Model
AutoQoS–VoIP
Model
Untrusted Server +
Scavenger Model
IP Phone + PC +
Scavenger (Basic) Model
This section includes the following topics:
Configuration
Catalyst MLS QoS Verification Command
Trust-DSCP
Uplinks to
Distribution Layer
Global1P3Q1T
Queuing
Configuring a Catalyst 2950 to trust an endpoint is fairly straightforward, as shown below. The trusted
endpoint should be assigned either the voice VLAN (VVLAN) or the data VLAN (DVLAN) with the
appropriate switchport commands.
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