Enabling Qos Globally - Cisco Catalyst 3550 series Software Configuration Manual

Configuring Standard QoS
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Enabling QoS Globally

By default, QoS is disabled on the switch, which means that the switch offers best-effort service to each
packet regardless of the packet contents or size. All CoS values map to egress queue 1 with both tail-drop
thresholds set to 100 percent of the total queue size for Gigabit-capable Ethernet ports. On 10/100
Ethernet ports, all CoS values map to egress queue 1, which uses minimum-reserve level 1 and can hold
up to 100 packets. When the buffer is full, packets are dropped.
Beginning in privileged EXEC mode, follow these steps to enable QoS:
Command
Step 1 configure terminal
Step 2
interface range port-range
Step 3
flowcontrol receive off
flowcontrol send off
Step 4
exit
Step 5 mls qos
Step 6
end
Step 7
show mls qos
Step 8 copy running-config startup-config
After QoS is enabled, the default settings are as shown in
To disable QoS, use the no mls qos global configuration command.
Catalyst 3550 Multilayer Switch Software Configuration Guide
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Layer 3 QoS ACLs and other QoS features related to Layer 3 information are not supported on tunnel
ports. MAC-based QoS is supported on tunnel ports. When applied to trunk ports, Layer 3 QoS ACLs do
not work for VLANs that include tunnel ports.
Do not use the show policy-map interface privileged EXEC command to display classification
information for incoming traffic. The interface keyword is not supported, and you should ignore the
statistics shown in the display. Instead, you should specify the DSCPs to be monitored by using the mls
qos monitor dscp dscp1 ... dscp8 interface configuration command, and then you should use the show
mls qos interface interface-id statistics privileged EXEC command. For more information about these
commands, refer to the command reference for this release.
Purpose
Enter global configuration mode.
Enter interface configuration mode, and execute a command
on multiple interfaces.
You can define up to five interface ranges with a single
command, with each range separated by a comma.
All interfaces in a range must be the same type; that is, all Fast
Ethernet ports or all Gigabit Ethernet ports.
Disable flowcontrol on all interfaces.
Return to global configuration mode.
Enable QoS globally.
Return to privileged EXEC mode.
Verify your entries.
(Optional) Save your entries in the configuration file.
Table 29-4 on page
Chapter 29 Configuring QoS
29-25.
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