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increasing output drops in class-default

Unanswered Question
Oct 24th, 2014
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Hi guys

 

A cisco 1905 is experiencing output drops when I ping with tos0. If I ping with any other class, ip prec 3, 4 or 5 there are no packet drops. For ip prec 5 I have a LLQ configured, for IP 4 just CBWFQ as well as for ipp 3 and 0

For IPP3 and 0 I have WRED. Most traffic LAN goes to class default, in LAN interface there isnt a set precedence

policer, if I increase the WRED threshhold from 20 to 30, will it work?, should I do the same for class IPP3?

 

 

#sh int Serial0/0/0                 
Serial0/0/0 is up, line protocol is up
  Hardware is WIC MBRD Serial
  Description: INTERFACE WAN PAHO
  Internet address is 187.92.255.118/30
  MTU 1500 bytes, BW 1984 Kbit/sec, DLY 20000 usec,
     reliability 255/255, txload 173/255, rxload 37/255
  Encapsulation PPP, LCP Open
  REQsent: CDPCP
  Open: IPCP, loopback not set
  Keepalive set (10 sec)
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters 00:00:47
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 18
  Queueing strategy: Class-based queueing
  Output queue: 0/1000/0 (size/max total/drops)
  30 second input rate 292000 bits/sec, 199 packets/sec
  30 second output rate 1348000 bits/sec, 243 packets/sec
     9071 packets input, 1502698 bytes, 0 no buffer
     Received 0 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     11041 packets output, 7540138 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 unknown protocol drops
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up

#sh int Serial0/0/0
Serial0/0/0 is up, line protocol is up
  Hardware is WIC MBRD Serial
  Description: INTERFACE WAN PAHO
  Internet address is 187.92.255.118/30
  MTU 1500 bytes, BW 1984 Kbit/sec, DLY 20000 usec,
     reliability 255/255, txload 203/255, rxload 23/255
  Encapsulation PPP, LCP Open
  REQsent: CDPCP
  Open: IPCP, loopback not set
  Keepalive set (10 sec)
  Last input 00:00:00, output 00:00:00, output hang never
  Last clearing of "show interface" counters 00:16:17
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 106
  Queueing strategy: Class-based queueing
  Output queue: 3/1000/0 (size/max total/drops)
  30 second input rate 183000 bits/sec, 131 packets/sec
  30 second output rate 1581000 bits/sec, 198 packets/sec
     131712 packets input, 26795737 bytes, 0 no buffer
     Received 0 broadcasts (0 IP multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
     177099 packets output, 151447099 bytes, 0 underruns
     0 output errors, 0 collisions, 0 interface resets
     0 unknown protocol drops
     0 output buffer failures, 0 output buffers swapped out
     0 carrier transitions
     DCD=up  DSR=up  DTR=up  RTS=up  CTS=up

 

 

Show policy-map

 

 Class-map: class-default (match-any)
          183317 packets, 159085668 bytes
          30 second offered rate 1511000 bps, drop rate 3000 bps
          Match: any
          Queueing
          queue limit 64 packets
          (queue depth/total drops/no-buffer drops) 2/114/0
          (pkts output/bytes output) 183307/158995075
          bandwidth 656 kbps
            Exp-weight-constant: 9 (1/512)
            Mean queue depth: 3 packets
            class     Transmitted       Random drop      Tail drop          Minimum        Maximum     Mark
                      pkts/bytes     pkts/bytes       pkts/bytes          thresh         thresh     prob
            
            0          183307/158995075     114/103301         0/0                 20            40  1/10
            1               0/0               0/0              0/0                 22            40  1/10
            2               0/0               0/0              0/0                 24            40  1/10
            3               0/0               0/0              0/0                 26            40  1/10
            4               0/0               0/0              0/0                 28            40  1/10
            5               0/0               0/0              0/0                 30            40  1/10
            6               0/0               0/0              0/0                 32            40  1/10
            7               0/0               0/0              0/0                 34            40  1/10

 

 

policy-map QoS_Out
 class Mgmt_Out
  bandwidth 16
  set ip precedence 6
 class IPP5_Out
  priority 160
  police rate 160000  burst 30000  peak-burst 60000
   conform-action set-prec-transmit 5
   exceed-action drop
   violate-action drop
 class IPP4_Out
  bandwidth 640
  set ip precedence 4
 class IPP3_Out
  bandwidth 512
  random-detect
  set ip precedence 3
 class class-default
  bandwidth 656
  random-detect
  set ip precedence 0
policy-map Shaping_Datos
 class class-default
  shape average 1984000
  service-policy QoS_Out

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Joseph W. Doherty Fri, 10/24/2014 - 12:20
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Posting

"if I increase the WRED threshhold from 20 to 30, will it work?,"  Will what work, stopping the drops?

Well, your interface shows txload 203/255 for 30 seconds, so that's fairly busy.  WRED is doing what's it's supposed to, drop packets randomly before they tail drop; which appears to be true in your cases as WRED didn't registered any tail drops.

PS:

BTW, what's the serial interface's physical bandwidth?  I'm wondering whether you really need to shape.

Alejandro Manue... Mon, 10/27/2014 - 13:14
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the bandwidth set is 1984 Kbit/seg which is the CIR, shaping is of no use, isnt it?

 

h controllers serial 0/0/0
Interface Serial0/0/0
Hardware is SCC
DTE V.35
Clock Freq detected Rx clk/Tx clk 1902055/1902057 (+-10%)

 

Joseph W. Doherty Tue, 10/28/2014 - 04:47
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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

Correct.  There's little point shaping for the local interface's bandwidth.

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