Cisco Catalyst 3550

2-240
Catalyst 3550 Multilayer Switch Command Reference
OL-8566-02
Chapter 2 Catalyst 3550 Switch Cisco IOS Commands
mls qos
mls qos
Use the mls qos global configuration command to enable quality of service (QoS) for the entire switch.
When the mls qos command is entered, QoS is enabled with the default parameters on all ports in the
system. Use the no form of this command to reset all the QoS-related statistics and to disable the QoS
features for the entire switch.
mls qos
no mls qos
Syntax Description This command has no arguments or keywords.
Defaults QoS is disabled. Table 2-5 shows the default QoS settings when QoS is disabled.
When QoS is disabled, there is no concept of trusted or untrusted ports because the packets are not
modified (the CoS, DSCP, and IP precedence values in the packet are not changed).
Ta b l e 2-5 Default QoS Configuration when QoS is Disabled
Port
Type
QoS
State
Egress traffic
(DSCP
1
and CoS
2
Value)
1. Differentiated Services Code Point
2. Class of service
Queue
Queue
Weights
Tail-drop
Thresholds
CoS Mapping
to Queue
Gigabit-capable
Ethernet ports
Disabled Pass through. All the queue RAM
is allocated to queue
1 (no expedite
queue).
– 100%, 100%
WRED
3
is
disabled.
3. Weighted Random Early Detection
All CoS values
map to queue 1.
10/100 Ethernet
ports
Disabled Pass through. Each of the eight
minimum-reserve
levels have a buffer
size of 100 packets.
The queue selects
the level.
– – All CoS values
map to queue 1.