Enterprise QoS Solution Reference Network Design Guide

Catalyst 2970/3560/3750—QoS Considerations and Design
Figure 2-16 Access Layer Catalyst 2970/3560/3750 QoS Design Options
Enable QoS
Globally
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Figure 2-17 Distribution Layer Catalyst 3750 QoS Design
Enterprise QoS Solution Reference Network Design Guide
Chapter 2 Campus QoS Design
Since the QoS features and configuration syntax are identical for the Catalyst 2970, 3560 and 3750, from
a QoS design recommendation perspective, they are subsequently addressed as a single switch.
As with the Catalyst 3550, QoS is globally disabled by default on the Catalyst 2970/3560/3750. While
QoS is disabled, all frames/packets are passed-through the switch unaltered (which is equivalent to a
trust CoS and trust DSCP state on all ports). When QoS is globally enabled, however, all DSCP and CoS
values are (by default) set to 0 (which is equivalent to an untrusted state on all ports).
QoS must be enabled globally for configured policies to become effective. The example below shows
how to verify if QoS has been enabled or not and also how it can be globally enabled.
Example 2-26 Enabling QoS Globally on the Catalyst 2970/3560/3750
CAT2970#show mls qos
QoS is disabled
CAT2970#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
CAT2970(config)#mls qos
CAT2970(config)#end
CAT2970#
CAT2970#show mls qos
QoS is enabled
CAT2970#
Trusted-Endpoint
Model
AutoQoS–VoIP
Model
PC + SoftPhone +
Scavenger Model
Untrusted Server +
Scavenger Model
IP Phone + PC +
Scavenger (Basic) Model
IP Phone + PC +
Scavenger (Adv) Model
Enable QoS
Globally
Access-Edges
Trust-DSCP
1P3Q3T
Queuing + WTD
1P3Q3T
Queuing + WTD
1P3Q3T
Queuing + WTD
1P3Q3T
Queuing + WTD
1P3Q3T
Queuing + WTD
1P3Q3T
Queuing + WTD
Interswitch Links
1P3Q3T
Queuing + WTD
Trust-DSCP
Uplinks to
Distribution Layer
1P3Q3T Queuing +
WTD
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