Please help verify rate-limit command

Answered Question
Nov 3rd, 2009
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We have a partial DS3 circuit that is 18Mb. We have four facilities that connect through an IPSEC connection on this DS3. Three of these facilities just connect to us for green screen however yesterday our forth facility maxxed out the connection so I want to put a rate limit their connection.


I am looking to put a cap of 14Mb, this will keep 4Mb free while also triggering the 75% utilization alert should the main facility be maxing out their rate-limit. I believe this command should perform the actions that I require:


rate-limit input 10000 2000 4000 conform-action transmit exceed-action drop

rate-limit output 10000 2000 4000 conform-action transmit exceed-action drop


Should be ~10Mb normal bandwidth, burstable to ~12Mb and cap at ~14Mb. Does this command look correct?


Thank you for your time.

Correct Answer by Giuseppe Larosa about 7 years 4 months ago

Hello Eric,

be aware that rate is expressed in bps so 10000 means only 10 Kbps.


see command reference


http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_q1.html#wp1054922


you should use

rate-limit output 14000000 2625000 5250000 conform-action transmit exceed-action drop




the recommended rules to dimension buffers are:


normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds


extended burst = 2 * normal burst



see

http://www.cisco.com/en/US/docs/ios/qos/configuration/guide/polcing_shping_oview_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1000977

However, you could consider a less aggressive policy that is to use outbound shaping.


policy-map shape_all_14Mbps

class class-default

shape average 14000000


! here rate is in bps


see


http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_s1.html#wp1060033


Hope to help

Giuseppe





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Correct Answer
Giuseppe Larosa Tue, 11/03/2009 - 08:25
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Hello Eric,

be aware that rate is expressed in bps so 10000 means only 10 Kbps.


see command reference


http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_q1.html#wp1054922


you should use

rate-limit output 14000000 2625000 5250000 conform-action transmit exceed-action drop




the recommended rules to dimension buffers are:


normal burst = configured rate * (1 byte)/(8 bits) * 1.5 seconds


extended burst = 2 * normal burst



see

http://www.cisco.com/en/US/docs/ios/qos/configuration/guide/polcing_shping_oview_ps6350_TSD_Products_Configuration_Guide_Chapter.html#wp1000977

However, you could consider a less aggressive policy that is to use outbound shaping.


policy-map shape_all_14Mbps

class class-default

shape average 14000000


! here rate is in bps


see


http://www.cisco.com/en/US/docs/ios/qos/command/reference/qos_s1.html#wp1060033


Hope to help

Giuseppe





randhir.singgh1 Wed, 05/11/2016 - 19:04
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I configured outbound shaping:


DKG-NthSydney#sho policy-map
  Policy Map Corp-Shape
    Class class-default
      Average Rate Traffic Shaping
      cir 19000000 (bps)



*************************************************************************************************

DKG-NthSydney#sho policy-map interface fastEthernet 4
 FastEthernet4

  Service-policy output: default

    Class-map: default
      20639677 packets, 18379225189 bytes
      5 minute offered rate 1032000 bps, drop rate 0000 bps
      Match: any
      Queueing
      queue limit 64 packets
      (queue depth/total drops/no-buffer drops) 0/9013/0
      (pkts output/bytes output) 20630664/18366374824
      shape (average) cir 19000000, bc 76000, be 76000
      target shape rate 19000000

But there is still congestion in network. I check with ISP who advised that link is jumping upto 80 MBPS. Not sure why policy-map not working.

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