Rate limit download traffic...

Unanswered Question
Aug 6th, 2010

Which is best way to allocate bandwidth for download traffic.I have four different applications which will be used by the users.Users used to download the files from each applications.

I want to rate limit this download traffic for each application with different bandwidth rate.I need to perform this at my local router.What is the best way of doing it.

CBWFQ is applied as out put to the interface.Is there any way to control the download traffic.

I have this problem too.
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Tharak Abraham Fri, 08/06/2010 - 20:55


If you know the port number of these applications, then you could define extended access list to match the source-port (reffering to the appln)

eg: access-list 100 permit udp/tcp any any eq .

After this you could use the normal MQC to create 4 Class maps to match the traffic from the corresponding appln

Then create Policers based on your bandwidth under the respective classes created and slap it inbound in interface facing the DMZ or Internet.

uthayaman Mon, 08/09/2010 - 22:47

Abraham!!! Thx for the suggestion.

I had gone through CAR documentations.I think percentage based policing will help me.But i stuck with bc and be parameters.My total link rate is 2MB out of which i need to assign 50% to one application and 10 % to other application.Rest can used by other traffic download.

How shall i calculate be and bc in

police cir percent percentage [burst-in-ms] [bc conform-burst-in-msec ms] [be peak-burst-in-msec ms] [ pir percent percent]


uthayaman Tue, 08/10/2010 - 09:50

Hi i tried rate limit with police feature.But then only i realized(Correct me if i am wrong) that this will always rate limit my traffic to the allocated bandwidth even though link is not fully utilized.My requirement is , users can download to the maximum link capcity when there is no other applications traffic.

Rate limit should be available only when there is a congestion.

Becasue during the non business hours users used to download the files from the application.During this time also they are not able to download the file and my policy map out put shows drop action.

Class-map: prod_app_class (match-all)
      663605 packets, 100448811 bytes
      30 second offered rate 484000 bps, drop rate 145000 bps
      Match: access-group name prod_app
          cir 350000 bps, bc 65625 bytes
        conformed 82955 packets, 11804980 bytes; actions:
        exceeded 52849 packets, 5287728 bytes; actions:
        conformed 341000 bps, exceed 145000 bps

During this time my bandwidth utlization was only 550 kbps.

show inter fas 0/0
FastEthernet0/0 is up, line protocol is up
  Hardware is Gt96k FE, address is 0024.977d.5cce (bia 0024.977d.5cce)
  Description: $2MB$
  Internet address is
  MTU 1500 bytes, BW 2000 Kbit/sec, DLY 100 usec,
     reliability 255/255, txload 14/255, rxload 71/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, 100BaseTX/FX
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:04, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  30 second input rate 557000 bits/sec, 442 packets/sec
  30 second output rate 114000 bits/sec, 188 packets/sec
     11924794 packets input, 624637893 bytes
     Received 10 broadcasts, 0 runts, 0 giants, 0 throttles

Please suggest which way i can have control on the download traffic.

mlund Fri, 09/03/2010 - 04:26


Here is a suggestion You can try. It is not recomended by cisco and I haven't done it myself, also the percentage will probably not be so precice You want.

The idea is to do a MQC on the outgoing interface towards the clients, also the shape value is set a little bit lower than the incoming rate, so, if the incoming rate is higher than 1,9M then the router starts to shape the traffic and as a result of shaping it also starts to queue traffic and drop traffic in the classes that is sending more than there respective percent. As a result of dropping , tcp flows will slow down. This will not work with udp based traffic, and also it's not so precise in the percentage count, but it may be worth trying it.

policy-map test

class nr1

  bandwidth percent 50

class nr2

  bandwidth percenet 10


policy-map shaping

class class-default

  shape average 1900000

  service-police test


interfrace < outgoing interface >

service-policy output shaping



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