HQOS Order of Operation

[mpaul_vijay]

Hi All

I have series of question regarding the order of operation of the HQOS configured and shaping applied.

interface fa0/0

service-policy out level1

class level1

match <src-dest>

Policy-map level1

class level1

bandwith 2000

shape average 2000000

service-policy level2

class CLASS_A

match <src-dest(CLASSA)>

class CLASS_B

match <src-dest(CLASSB)>

policy-map level2_A

class CLASS_A

bandwith 1000

shape average 2000000

service-policy level3_A

policy-map level2_A

class CLASS_B

bandwith 1000

shape average 2000000

service-policy level3_A

class-map citrix

match application citrix 

policy-map level3_A

class citrix 

bandwidth 500

class-default

bandwidth 500

fair-queue

random-detect

policy-map level3_B

class citrix 

bandwidth 500

class-default

bandwidth 500

fair-queue

random-detect

With this configuration above for the below topo

                      --------------------SOHO1

HUB-----------

                     ---------------------SOHO2

With bandwidth configured at 2 Mbps at the level1 and shaped to average 2Mbps where the link bandwidth is 4Mbps we are seeing the counters increment the more than 2Mpbs when traffic is sent over 3Mbps, 

1. Wouldnt the traffic be shaped to 2Mbps and not more than 2 Mbps should be sent over the link when CIR is oversubcribed

2.I see all the hits happening at level1 default-class , so what is the order of operation for this configuration above.

3.Also the offered rate is higher than the shaped averag.

Thanks Everyone 

[Akash Agrawal]

Hi,

If all traffic is being classified under class class-default in policy-map level1 then no other action would be applied as shaping you have configured under class level1 and nested policy-maps as well.

Please check configuration of class level1 and if that match criteria is properly matching your traffic or not. In such queries , output of "show policy-map interface <int>" helps to understand it better.

--Pls be kind to rate helpful posts--

Regards,

Akash

[mpaul_vijay]

I had missed a match statement but still with that corrected , when bandwidth and shaped at level one is 2 Mbps and when the link is oversubscribed to 3Mbps , the offered rate is seen as 2600000 and drop rate at 400000.

[Akash Agrawal]

If i remember correctly "offered rate - drop rate" is actual traffic passing through that policy-map so if offered rate is 2600000 and drop rate is 400000 then traffic passing through that class is 2200000. Second thing drop rate is instantaneous while offered rate is average rate which could be average of 5 min (by default) or minimum 30 sec if configured.

Regards,

Akash

[jagannath.iob]

Hi Akash,

Hope you are doing good.

we are observing some huge drops on default qos class for output traffic only when there is high load . we have changed the queue limit till 2048 but no luck . i am attaching the config and sample outputs . please let us know what was the issue.

Thanks,

jagannath

[vamikhai]

Hello.

The drops are due to WRED configured in class -default.

You either may remove it or change min/max thresholds to some higher value (up to 1024 -eq hald of the queue-limit).

btw, what is the device and IOS release you are running?

[jagannath.iob]

The device is 3925 router with SPE 200 .

Can you please tell me how to change the min.max thresholds value becoz we cannot change the WRED as it is the standard template which we are using from long time.

Thank you.

[jagannath.iob]

please find the IOS version

System image file is "flash0:/c3900e-universalk9-mz.SPA.154-3.M3.bin