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Catalyst2950 and Catalyst2955 Switch Software Configuration Guide
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Chapter30 Co nf iguring QoS
Standard QoS Configuration Examples
Figure30-5 QoS Configuration Example Network
QoS Configuration for the Existing Wiring Closet
Figure 30-5 shows an existing wiring closet with Catalyst 2900 XL and 3500 XL switches, for example.
These switches are running Cisco IOS Release 12.0(5)XP or later, which supports the QoS-based IEEE
802.1p CoS values. QoS classifies frames by assigning priority-indexed CoS values to them and gives
preference to higher-priority traffic.
Recall that on the Catalyst 2900 and 3500 XL switches, you can c lassif y u nta gge d (na tive) Ether net
frames at the ingress ports by setting a default CoS priority (switchport priority default
default-priority-id interface configuration command) for each port. For IEEE 802.1Q frames with tag
information, the priority value from the header frame is used. On the Catalyst 3524-PWR X L and3548
XL switches, you can override this priority with the default value by using the switchport priority
default override interface configuration command. For Catalyst 2950 and Catalyst 2900 XL switches
and other 3500 XL models that do not have the override feature, the Ca taly st 35 50-12T swi tch at the
distribution layer can override the 802.1p CoS value by using the mls qos cos override interface
configuration command.
Cisco router
Existing wiring closet Intelligent wiring closet
To Internet
Gigabit
Ethernet
0/2 Gigabit
Ethernet
0/1
Trunk
link Trunk
link
End
stations
Video server
172.20.10.16
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