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New Member

Packs drop on a non-congest link (for Voice)

Hi Everyone

I have a question regarding QOS packs drop on a non-congest link

My router Gi0/0 connects to ISP and here's the QOS configuration under this port:

--------------------------------------------------------------------------------------

QOS:

class-map match-any h_out

match ip precedence 4

class-map match-any l_out

match ip precedence 2

class-map match-any Voice_out

match ip precedence 5

!

!

policy-map Traffice-priority

class Voice_out

    priority 320

class h_out

    bandwidth percent 24

class l_out

    bandwidth percent 16

class class-default

    bandwidth percent 38

policy-map SHAPER-WAN

class class-default

    shape average 1500000

  service-policy Traffice-priority

interface GigabitEthernet0/0

description "CE e1"

bandwidth 1544

ip address X.X.X.X Y.Y.Y.Y

load-interval 30

duplex full

speed 10

!

service-policy output SHAPER-WAN

--------------------------------------------------------------------------------------

Show Output:

Router#show policy-map interface gigabitEthernet 0/0

GigabitEthernet0/0

  Service-policy output: SHAPER-WAN

    Class-map: class-default (match-any)

      19559 packets, 7543324 bytes

      30 second offered rate 251000 bps, drop rate 47000 bps

      Match: any

      Queueing

      queue limit 64 packets

      (queue depth/total drops/no-buffer drops) 0/1110/0

      (pkts output/bytes output) 18468/6056654

      shape (average) cir 1500000, bc 6000, be 6000

      target shape rate 1500000

      Service-policy : Traffice-priority

        queue stats for all priority classes:

          queue limit 64 packets

          (queue depth/total drops/no-buffer drops) 0/0/0

          (pkts output/bytes output) 15623/4935338

        Class-map: Voice_out (match-any)

          16733 packets, 6335376 bytes

          30 second offered rate 207000 bps, drop rate 47000 bps  ------------------------------->you can see that 30 second offered rate is 207000bps which is less than priority 320 kbps, why there are some drop from this class?

          Match: ip precedence 5

            16733 packets, 6335376 bytes

            30 second rate 207000 bps

          Match: ip dscp ef (46)

            0 packets, 0 bytes

            30 second rate 0 bps

          Priority: 320 kbps, burst bytes 8000, b/w exceed drops: 1110

        Class-map: h_out (match-any)

          0 packets, 0 bytes

          30 second offered rate 0 bps, drop rate 0 bps

          Match: ip precedence 4

            0 packets, 0 bytes

            30 second rate 0 bps

          Queueing

          queue limit 64 packets

          (queue depth/total drops/no-buffer drops) 0/0/0

          (pkts output/bytes output) 0/0

          bandwidth 24% (360 kbps)

        Class-map: l_out (match-any)

          0 packets, 0 bytes

          30 second offered rate 0 bps, drop rate 0 bps

          Match: ip precedence 2

            0 packets, 0 bytes

            30 second rate 0 bps

          Queueing

          queue limit 64 packets

          (queue depth/total drops/no-buffer drops) 0/0/0

          (pkts output/bytes output) 0/0

          bandwidth 16% (240 kbps)

        Class-map: class-default (match-any)

          2826 packets, 1207948 bytes

          30 second offered rate 46000 bps, drop rate 0 bps

          Match: any

          Queueing

          queue limit 64 packets

          (queue depth/total drops/no-buffer drops) 0/0/0

          (pkts output/bytes output) 2845/1121316

          bandwidth 38% (570 kbps)

My question is marked as Red, could anyone share some thought about that ?

Thanks a lot

4 REPLIES
New Member

Packs drop on a non-congest link (for Voice)

Hmm - the configuration is good, the only thing I can think of is you are exhausting the shaper token buckets because of bursty traffic.

Is there any TCP traffic getting marked as Prec 5 that could be entering this queue?

Please try doubling the bucket sizes and seeing if that resolves - and then investigate what traffic might be causing this if that works.

Super Bronze

Re: Packs drop on a non-congest link (for Voice)

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

You're looking at a 30 average rate, but policing happens in milliseconds.  I.e. your traffic goes overrate within a millisecond time window (looks like 200ms) it will be dropped.

New Member

Re: Packs drop on a non-congest link (for Voice)

May I know where you find my  traffic goes overrate within a millisecond time window? Thanks

Super Bronze

Re: Packs drop on a non-congest link (for Voice)

Disclaimer

The    Author of this posting offers the information contained within this    posting without consideration and with the reader's understanding that    there's no implied or expressed suitability or fitness for any  purpose.   Information provided is for informational purposes only and  should not   be construed as rendering professional advice of any kind.  Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In    no event shall Author be liable for any damages whatsoever  (including,   without limitation, damages for loss of use, data or  profit) arising  out  of the use or inability to use the posting's  information even if  Author  has been advised of the possibility of such  damage.

Posting

May I know where you find my  traffic goes overrate within a millisecond time window? Thanks

You infer that from knowing how it works and the fact it's recording drops, but also:

Class-map: Voice_out (match-any)

          16733 packets, 6335376 bytes

          30 second offered rate 207000 bps, drop rate 47000 bps  ------------------------------->you  can see that 30 second offered rate is 207000bps which is less than  priority 320 kbps, why there are some drop from this class?

          Match: ip precedence 5

            16733 packets, 6335376 bytes

            30 second rate 207000 bps

          Match: ip dscp ef (46)

            0 packets, 0 bytes

            30 second rate 0 bps

          Priority: 320 kbps, burst bytes 8000, b/w exceed drops: 1110

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