QoS on Router 2921 not working

pablo.poskal · ‎07-01-2015

In our Cisco 2921 router we have a QoS configured, the router have IOS Version 15.1(4)M10.

The problem is that we have in a subinterface a QoS configured to use 13 Mbps to download and upload from Internet, and we notice that some times the QoS allow more traffic than the 13 Mbps configured.

The configuration on that subinterface is:

!
policy-map limit-13Mbps-New
class class-default
police cir 13000000
conform-action transmit
exceed-action drop
violate-action drop
!
interface GigabitEthernet0/0.38
bandwidth 13000
service-policy input limit-13Mbps-New
service-policy output limit-13Mbps-New
!

when we consult the QoS performance have the next result:

Service-policy input: limit-13Mbps-New

Class-map: class-default (match-any)
119429922 packets, 14124877914 bytes
30 second offered rate 221000 bps, drop rate 0 bps
Match: any
police:
cir 13000000 bps, bc 406250 bytes, be 406250 bytes
conformed 119429857 packets, 14124793385 bytes; actions:
transmit
exceeded 66 packets, 84599 bytes; actions:
drop
violated 0 packets, 0 bytes; actions:
drop
conformed 221000 bps, exceed 0 bps, violate 0 bps

Service-policy output: limit-13Mbps-New

Class-map: class-default (match-any)
196373825 packets, 271226024337 bytes
30 second offered rate 44730000 bps, drop rate 32439000 bps
Match: any
police:
cir 13000000 bps, bc 406250 bytes, be 406250 bytes
conformed 187366362 packets, 257771248739 bytes; actions:
transmit
exceeded 4570708 packets, 6852468990 bytes; actions:
drop
violated 4417762 packets, 6601090992 bytes; actions:
drop
conformed 12296000 bps, exceed 32000 bps, violate 32401000 bps

Notice in the output policy 30 second offered rate 44730000 bps and that is more that the 13 Mbps configured and more use than we expected in the Internet link.

Our monitoring system also shows some traffic that use more than the 13 Mbps.

There is any problem with the implementation of the QoS? with the router? or were is the problem?

Thanks in advance

Joseph W. Doherty · ‎07-01-2015

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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.

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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

Notice in the output policy 30 second offered rate 44730000 bps and that is more that the 13 Mbps configured and more use than we expected in the Internet link.

Yes, but further notice:

30 second offered rate 44730000 bps, drop rate 32439000 bps

or

44730000

32439000 -

========

12291000

pablo.poskal · ‎07-01-2015

Another thing, in spite of the diference that you are pointing, we notice in our monitoring system, that frecuenly some burst over 13 Mbps happens, sometimes that burst reach 18 and 25 Mbps, is that a normal thing?

Thanks in advance

Joseph W. Doherty · ‎07-01-2015

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

Are you sure you monitoring is looking at the correct variable?

What does the interface's RX/TX stats show?

pablo.poskal · ‎07-01-2015

i'm looking the OID by default that my snmp based tool use. When the interface that i'm talking you about use full 13 Mbps and the show policy-map shows more bps used than the configured one, the grapich on the tool shows some burst over the 13 Mbps, reaching 16 and 25 Mbps.

Thanks in advance for your help.

pablo.poskal · ‎07-01-2015

Hi Joseph, i notice the thing that you are pointing, but i have a question, if that interface have configured 13 Mbps in output and input why the output reach the 44,7 Mbps?

The question is because, we notice that the internet link (is in other interface on the same router) is affected by that 44,7 Mbps, so that interface that is setup to 13 Mbps use 44,7 Mbps on our Internet link. how can we control this?

Thanks in advance

Joseph W. Doherty · ‎07-01-2015

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

Well, since your high value policer is showing on egress, another interface on the same device could show the 44 Mbps ingress. Is that what you're seeing?

pablo.poskal · ‎07-01-2015

Yes, that router have several interfaces, one with the internet link and other subinterfaces.

In sometimes this interface that i am talking you about was using full 13 Mbps, the other interfaces was using like 1Mbps, if we add the other subinterfaces don't reach more than 10 Mbps, and when we saw the Internet link, had all the 60 Mbps full downloading and our monitoring system confirmed. That why i'm worry about this case, is consuming more internet bandwith than i'm expected.

Thanks in advance for your help