perfSONAR User Q&A and Other Discussion

[Brian Tierney <>]

Very strange indeed.

I'd start by doing a tcpdump capture of a good run vs a bad run, and look at 
the tcptrace output.

See:

http://fasterdata.es.net/performance-testing/network-troubleshooting-tools/tcpdump-tcptrace/


On Oct 16, 2013, at 3:07 AM, Roderick Mooi 
<>
 wrote:

> 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:8085/perfSONAR_PS/services/pSB&key=d9013ce7df20b8bbe45defeaeae785d6&keyR=0a0ed6c928edf28976414a2cc7e87d6f&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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