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Understanding "mls qos queue-set output"


     I've been  working on breaking down and understanding the default auto qos  configuration on a Cisco 3750 in the hopes of putting together a QoS  strategy that will fit our environment.  I'm having some difficulty  understanding how the "mls qos queue-set output" syntax works.

     From another post, at , the author offers the following example and explanation;

mls qos queue-set output <1/2> threshold 2 400 400 100 400

thresshold 1: 400%

thresshold 2: 400%

thresshold 3: 100% (implicit, not configurable)

reserved: 100%

max: 400%

     However, I'm having trouble understanding what is meant.  Here, it looks like it's saying, for example;

mls qos queue-set output 1 threshold 2 400 400 100 400

How  come there is syntax stating "threshold 2" when in the succeeding part  the 400 refers to thresshold 1 and threshold 2 again?  The syntax 400 400 is, apparently, already referring to thresshold 1 and 2, no?

Cisco Employee

Understanding "mls qos queue-set output"


The number after threshold identify the hardware queue. So the later numbers are specifications for this particular queue (threshold1, threshold2, reserved, maximum). So you basically configuring QoS template number X for queue Y with specific values with command:

mls qos queue-set output X threshold Y 400 400 100 400

X is either 1 or 2, Y 1-4 (though may vary based on HW specifics)

You can go through this document for more info:


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