Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Community Member

QOS- Police

I have applied below police configuration into interface and below is the traffic statistic. I don't understand why  1011000 bps as shown as exceeded whereas normal traffic has not reached the set limit(100000000 bps). 

rate-limit input 100000000 3125000 3125000 conform-action transmit exceed-action transmit

CHN-ABS-MPLS-RTR-01#sh int GigabitEthernet0/1.701 rate-limit

GigabitEthernet0/1.701 ******Hub-HUb VRF********

  Input

    matches: all traffic

      params:  100000000 bps, 3125000 limit, 3125000 extended limit

      conformed 408163914 packets, 262578M bytes; action: transmit

      exceeded 14748451 packets, 10785M bytes; action: transmit

      last packet: 0ms ago, current burst: 478 bytes

      last cleared 23:42:04 ago, conformed 24619000 bps, exceeded 1011000 bps

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

QOS- Police

Hi,

You seems to have bursty traffic. QoS is using concept of time slots and it check the particular number of traffic on that time slot. If for a single time slot you get a lot of traffic which will be over your CIR (100MB) then all traffic above that will be consiedred as exceeded. In the rest time slots you can have low rates - thus total rate can be lower than your CIR even if on particular time slot you had a burst.

So bursty nature of traffic can explain why you have exceeded traffic - those occured during the traffic spike.

Hope this helps,

Nik

3 REPLIES
Cisco Employee

QOS- Police

Hi,

You seems to have bursty traffic. QoS is using concept of time slots and it check the particular number of traffic on that time slot. If for a single time slot you get a lot of traffic which will be over your CIR (100MB) then all traffic above that will be consiedred as exceeded. In the rest time slots you can have low rates - thus total rate can be lower than your CIR even if on particular time slot you had a burst.

So bursty nature of traffic can explain why you have exceeded traffic - those occured during the traffic spike.

Hope this helps,

Nik

Community Member

QOS- Police

Your reply is quite helpful .But still I have some more doubts. What is the time period taken in this case to calculate average speed 24619000 bps. Is it since the police applied into the interface or 1 sec or 1/4 sec ? I have defined 4 slots(bc 3125000 bytes) for token fill up. If no traffic is passed through this interface in 1st one second, then will 12500000 additional bytes be allowed in next second ?

Super Bronze

QOS- Police

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

 

This is very common with policers for the reason Nik has described; for example, TCP during slow start.

What you can do is configure the policer to work across a longer time interval and/or use peak policing rather than average policing.

360
Views
0
Helpful
3
Replies
CreatePlease to create content