perfSONAR User Q&A and Other Discussion

[Alan Whinery <>]

You might also reveal something useful by using periodic reports in your
bwctl invocations (like " -i 1 ") you may find that the per second
reports show burstiness, or the lack of it.

On 10/16/2013 6:26 AM, Wefel, Paul wrote:
> Couple ideas
> 
> Run owamp between these two hosts looking for packet loss in only one
> direction.
> Check the switch interface that Dst is connected to looking for queue
> drops and pause frames being sent.
> 
> I have also seen strange issues with some NICS when offloading is enabled
> on them.
> 
> good luck, let us know what you find.
> 
> -paul
> NCSA @ UIUC
> 
> -----Original Message-----
> From: Roderick Mooi 
> <>
> Date: Wednesday, October 16, 2013 5:07 AM
> To: 
> ""
> <>,
>  
> ""
> <>
> Subject: [perfsonar-user] Help with inconsistent bwctl measurements
> 
>> Hi
>>
>> I have been trying to locate the cause of inconsistent measurements
>> between two nodes for a few weeks now without success. The pattern I'm
>> seeing is available at:
>>
>> https://192.96.2.247/serviceTest/bandwidthGraph.cgi?url=http://localhost:8
>> 085/perfSONAR_PS/services/pSB&key=d9013ce7df20b8bbe45defeaeae785d6&keyR=0a
>> 0ed6c928edf28976414a2cc7e87d6f&dstIP=192.96.2.247&srcIP=196.21.48.249&dst=
>> 192.96.2.247&src=perfsonara.sanren.ac.za&type=TCP&length=2592000
>>
>> Src-Dst is consistent but Dst-Src is not.
>>
>> Manual tests (attached) show the same behaviour without any indication of
>> cause - measures 941 Mbps then drops to 189 Mbps (end) and back to 941
>> (nothing different in the logs between "good" measurements and "bad"
>> ones). The only time I've seen something similar is when I was testing
>>from a 10 G interface to a 1 G interface which was subsequently being
>> flooded. In this case both interfaces are 1 G. I'm also not seeing any
>> problems with measurements along the path or between these nodes and any
>> other nodes. Additionally, there is very little (< 50 Mbps) real traffic
>> between these 2 nodes.
>>
>> Any ideas?
>>
>> Thanks!
>>
>> Roderick
>>
>> -- 
>> Roderick Mooi      | SANREN Engineer
>> -- 
>> 
>>  | +27 12 841 4111 | www.sanren.ac.za
>>
>>
>>
>>
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