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Qos and network throttling

andrewburridge
Level 1
Level 1

Hi guys,

I have a 3560 with a pretty standard autoqos setup, listed below:

mls qos map cos-dscp 0 8 16 26 32 46 48 56

mls qos srr-queue input bandwidth 90 10

mls qos srr-queue input threshold 1 8 16

mls qos srr-queue input threshold 2 34 66

mls qos srr-queue input buffers 67 33

mls qos srr-queue input cos-map queue 1 threshold 2  1

mls qos srr-queue input cos-map queue 1 threshold 3  0

mls qos srr-queue input cos-map queue 2 threshold 1  2

mls qos srr-queue input cos-map queue 2 threshold 2  4 6 7

mls qos srr-queue input cos-map queue 2 threshold 3  3 5

mls qos srr-queue input dscp-map queue 1 threshold 2  9 10 11 12 13 14 15

mls qos srr-queue input dscp-map queue 1 threshold 3  0 1 2 3 4 5 6 7

mls qos srr-queue input dscp-map queue 1 threshold 3  32

mls qos srr-queue input dscp-map queue 2 threshold 1  16 17 18 19 20 21 22 23

mls qos srr-queue input dscp-map queue 2 threshold 2  33 34 35 36 37 38 39 48

mls qos srr-queue input dscp-map queue 2 threshold 2  49 50 51 52 53 54 55 56

mls qos srr-queue input dscp-map queue 2 threshold 2  57 58 59 60 61 62 63

mls qos srr-queue input dscp-map queue 2 threshold 3  24 25 26 27 28 29 30 31

mls qos srr-queue input dscp-map queue 2 threshold 3  40 41 42 43 44 45 46 47

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 srr-queue output dscp-map queue 1 threshold 3  40 41 42 43 44 45 46 47

mls qos srr-queue output dscp-map queue 2 threshold 3  24 25 26 27 28 29 30 31

mls qos srr-queue output dscp-map queue 2 threshold 3  48 49 50 51 52 53 54 55

mls qos srr-queue output dscp-map queue 2 threshold 3  56 57 58 59 60 61 62 63

mls qos srr-queue output dscp-map queue 3 threshold 3  16 17 18 19 20 21 22 23

mls qos srr-queue output dscp-map queue 3 threshold 3  32 33 34 35 36 37 38 39

mls qos srr-queue output dscp-map queue 4 threshold 1  8

mls qos srr-queue output dscp-map queue 4 threshold 2  9 10 11 12 13 14 15

mls qos srr-queue output dscp-map queue 4 threshold 3  0 1 2 3 4 5 6 7

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 2 threshold 1 149 149 100 149

mls qos queue-set output 2 threshold 2 118 118 100 235

mls qos queue-set output 2 threshold 3 41 68 100 272

mls qos queue-set output 2 threshold 4 42 72 100 242

mls qos queue-set output 1 buffers 10 10 26 54

mls qos queue-set output 2 buffers 16 6 17 61

mls qos

We have this config on a few switches operating as L3 switches in spoke LANs, linking back to a central location.  Backups run from the spokes to the main office over these switches at night, and the data transfer rates are inexplicably slow.  Looking at the WAN links out from the switches, I can see that there is only about 5% utilization over the night period, and the backup software is not throttling.

Would this QoS setup throttle traffic on a link that is otherwise not being utilized?  As I understand, that's not how it should work at all, higher priority queues should be served first, but if there's no traffic in them, the lower priority ones should be fine.  I'm open to suggestions however!

Thanks for any help!

2 Replies 2

Shashank Singh
Cisco Employee
Cisco Employee

Hi Andrew,

Capture the output of "show platform port-asic stat drop" multiple times and see if you see TxQueue drop counters incrementing for any port. If you do, traffic would be getting dropped because of QoS configuration.

If you know the interfaces on this switch which could be dropping packets, perform "show platform pm if-num" and find out the internal port associated with that physical interface. Once you know the internal port, "sh platform port-asic stat drop port " will tell you if traffic is being dropped in its queues.

Hope this helps.

Cheers,

Shashank

Please rate this answer if you found the content useful

Hey, thanks for your reply!

I'll get checking the output from those counters and get back to you.

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