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Webcast-Catalyst9k
New Member

QoS on 3750/3560

Hello chaps, 

I am re-designing the QoS in an Enterprise network, which currently uses SRND4 Auto QoS for buffer/threshold/queues and queue-set configurations. However, this does not seem to be much useful for this kind of network, where we got only two types of traffic - Data and VoIP. 

 

SRND4 QoS though configures buffers and thresholds like that:

mls qos srr-queue output cos-map queue 1 threshold 3 5
mls qos srr-queue output cos-map queue 2 threshold 3 3 6 7
mls qos srr-queue output cos-map queue 3 threshold 3 2 4
mls qos srr-queue output cos-map queue 4 threshold 2 1
mls qos srr-queue output cos-map queue 4 threshold 3 0
mls qos queue-set output 1 threshold 1 138 138 92 138
mls qos queue-set output 1 threshold 2 138 138 92 400
mls qos queue-set output 1 threshold 3 36 77 100 318
mls qos queue-set output 1 threshold 4 20 50 67 400
 
mls qos queue-set output 1 buffers 10 10 26 54

 

 

So basically I am only interested for traffic in Q1 (cos 5) and Q4T3 (cos 0). At the moment, there are some buffers "wasted" for Q2 & Q3, which I'd like to re-locate to Q4 instead. I was thinking for something like that:

mls qos queue-set output 1 threshold 1 150 150 100 400
mls qos queue-set output 1 threshold 2 100 100 50 100
mls qos queue-set output 1 threshold 3
100 100 50 100
mls qos queue-set output 1 threshold 4 80 95 100 3200
!
mls qos queue-set output 1 buffers 10 5 5 80

!And then, on per-interface basis, to have this one:

interface fastethernet0/3

 srr-queue bandwidth share 10 5 5 100

 

Which should look like that:

 

Q1 - 10 buffers (each 256 bytes) with 400% borrowing from the common pool. Priority queue, 100% guaranteed. Weights for this queue are 10/(10+5+5+100) = 0.083% (which should be more than enough for user ports and single phone attached to it)

Q2 & Q3 - 5 buffers, 50% guaranteed. Weights are 0.04% for each queue.

Q4 - 80 buffers, maximum usage of common pool (3200) with weights 0.83%

 

What is your opinion about that? How does it look and do you reckon it's a good "design"? 

Many thanks in advance for your prompt response!

 

 

 

2 REPLIES

If you only have voice and

If you only have voice and data and auto-qos is enabled, why the redesign?
New Member

Because I see loads of

Because I see loads of packets being discarded in Q4.

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