perfSONAR User Q&A and Other Discussion

["Wefel, Paul" <>]

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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