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New Member

Output Dropps


i have a 3750 with 12.2.55SE7 and he has some output queue 3 dropps at threashold 3. As far as i remember the threshold three is a static parameter on the switch. In fact that there is only a telephone located at this port it is not easy to explain those dropps. We also noticed some retransmissions at the telephone so i need to find out if they match the dropps.

Here are some outputs:

Q1/Q0 ist a Prio queue, Q2 for Best Efford, Q3 for signalling in this case

  output queues enqueued:

queue:    threshold1   threshold2   threshold3


queue 0:           0           0           388077

queue 1:      147456      123815     2572166

queue 2:           0           0           333504

queue 3:           0           0           176711

  output queues dropped:

queue:    threshold1   threshold2   threshold3


queue 0:           0           0           0

queue 1:           0           0           0

queue 2:           0           0          13

queue 3:           0           0           0

#sh mls qos int gi x/x/x queueing


Egress Priority Queue : enabled

Shaped queue weights (absolute) :  25 0 0 0

Shared queue weights  :  1 30 35 5

The port bandwidth limit : 100  (Operational Bandwidth:100.0)

The port is mapped to qset : 1

So the mapping of the dscp to queues is not relevant here because we talk only of a phone - so someone have any suggestion what causes this T3 @ Q3 (q2 in the output) causing to dropp packets on a phoneport ?

Many Thanks !

Everyone's tags (3)

Output Dropps

I would say that 13 drops is not very many at all.  I do notice they are on Q2, whereas you say that your voice is on Q1 and your signalling on Q3.  I would therefore be searching for bursty background traffic, possibly on the access VLAN rather than the voice VLAN.  Do all the phone ports show these drops?  How is the access port configured ... do you have access VLAN and voice VLAN?

Kevin Dorrell


New Member

Re: Output Dropps


right, but i cleared those counters

In this case the show command is starting with counting on 0 -> Q2 (is Q3 in reallive) so were hitting here the signalling queue not the data-queue.

The telephone is located in the normal VLAN - so broadcasts and stuff reach the phone (but in Q2)..