perfSONAR User Q&A and Other Discussion

["Roderick Mooi" <>]

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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$ bwctl -f m -t 20 -s 192.96.2.247 -c 196.21.48.249 -I 150

bwctl[30717]: FILE=bwctl.c, LINE=2648, 33 seconds until test results available

RECEIVER START
bwctl: exec_line: iperf -B 196.21.48.249 -s -f m -m -p 5215 -t 20
bwctl: start_tool: 3590904379.537243
------------------------------------------------------------
Server listening on TCP port 5215
Binding to local address 196.21.48.249
TCP window size: 0.08 MByte (default)
------------------------------------------------------------
[ 14] local 196.21.48.249 port 5215 connected with 192.96.2.247 port 5215
[ ID] Interval       Transfer     Bandwidth
[ 14]  0.0-20.4 sec  2290 MBytes   941 Mbits/sec
[ 14] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
bwctl: stop_exec: 3590904404.550286

RECEIVER END
bwctl[30717]: FILE=bwctl.c, LINE=2046, 108 seconds until next testing period
bwctl[30717]: FILE=bwctl.c, LINE=2648, 33 seconds until test results available

RECEIVER START
bwctl: exec_line: iperf -B 196.21.48.249 -s -f m -m -p 5216 -t 20
bwctl: start_tool: 3590904523.028798
------------------------------------------------------------
Server listening on TCP port 5216
Binding to local address 196.21.48.249
TCP window size: 0.08 MByte (default)
------------------------------------------------------------
[ 14] local 196.21.48.249 port 5216 connected with 192.96.2.247 port 5216
[ ID] Interval       Transfer     Bandwidth
[ 14]  0.0-20.5 sec  2304 MBytes   941 Mbits/sec
[ 14] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
bwctl: stop_exec: 3590904547.764843

RECEIVER END
bwctl[30717]: FILE=bwctl.c, LINE=2046, 115 seconds until next testing period
bwctl[30717]: FILE=bwctl.c, LINE=2648, 33 seconds until test results available

RECEIVER START
bwctl: exec_line: iperf -B 196.21.48.249 -s -f m -m -p 5217 -t 20
bwctl: start_tool: 3590904679.252752
------------------------------------------------------------
Server listening on TCP port 5217
Binding to local address 196.21.48.249
TCP window size: 0.08 MByte (default)
------------------------------------------------------------
[ 14] local 196.21.48.249 port 5217 connected with 192.96.2.247 port 5217
[ ID] Interval       Transfer     Bandwidth
[ 14]  0.0-20.5 sec  2304 MBytes   941 Mbits/sec
[ 14] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
bwctl: stop_exec: 3590904704.140797

RECEIVER END
bwctl[30717]: FILE=bwctl.c, LINE=2046, 109 seconds until next testing period
bwctl[30717]: FILE=bwctl.c, LINE=2648, 31 seconds until test results available

RECEIVER START
bwctl: exec_line: iperf -B 196.21.48.249 -s -f m -m -p 5218 -t 20
bwctl: start_tool: 3590904822.323230
------------------------------------------------------------
Server listening on TCP port 5218
Binding to local address 196.21.48.249
TCP window size: 0.08 MByte (default)
------------------------------------------------------------
[ 14] local 196.21.48.249 port 5218 connected with 192.96.2.247 port 5218
[ ID] Interval       Transfer     Bandwidth
[ 14]  0.0-20.0 sec   452 MBytes   189 Mbits/sec
[ 14] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
bwctl: stop_exec: 3590904845.185349

RECEIVER END
bwctl[30717]: FILE=bwctl.c, LINE=2046, 118 seconds until next testing period
bwctl[30717]: FILE=bwctl.c, LINE=2648, 32 seconds until test results available

RECEIVER START
bwctl: exec_line: iperf -B 196.21.48.249 -s -f m -m -p 5219 -t 20
bwctl: start_tool: 3590904978.542190
------------------------------------------------------------
Server listening on TCP port 5219
Binding to local address 196.21.48.249
TCP window size: 0.08 MByte (default)
------------------------------------------------------------
[ 14] local 196.21.48.249 port 5219 connected with 192.96.2.247 port 5219
[ ID] Interval       Transfer     Bandwidth
[ 14]  0.0-20.4 sec  2285 MBytes   941 Mbits/sec
[ 14] MSS size 1448 bytes (MTU 1500 bytes, ethernet)
bwctl: stop_exec: 3590905001.558298

RECEIVER END