perfSONAR User Q&A and Other Discussion

["Niederberger, Ralph" <>]

Dear all,

yesterday I did some tests with bwctl software.

I am using

- MonPC-A as host initiating measurements between MonPC-B and MonPC-C.
- MonPC-B as Sendhost for iperf
- MonPC-C as Recvhost for iperf


Starting at MonPC-A the command

  /usr/local/bin/bwctl -s MonPC-B -c MonPC-C

I see with wireshark on host MonPC-A connections from high ports to port
4823 at hosts MonPC-B and MonPC-C.
So this is for initiating the measurement.

On MonPC-B I see, that MonPC-B and MonPC-C are starting communications on
high ports on both sides.
I assume they are  exchanging parameters for the later iperf measurement?
After this they are doing the iperf measurement using port 5001 on both
sides.

After the measurement has been done, the communications on the already
existing connections to host MonPC-A are used again to provide the
measurement output to this host. This communications use the high ports on
MonPC-A and the port 4823 on hosts MonPC-B and MonPC-C again.

So my questions:

A.) Is this the normal behavior.
B.) Can the communication be changed in the way that parameter exchanges
between MonPC-B and MonPC-C use predefined well known ports and not arbitray
high ports?

If this is normal behavior this would imply that MonPC-B and MonPC-C have to
trust each other. Opening of arbitrary ports between both hosts. From a
security point of view this very annoying.

Furthermore this would imply that measurements between administratively
separated domains, i.e. Multi Domain Monitoring would not be possible,
without mutual trust relationships.

Any comments, suggestions, feedback?

Best regards

Ralph
   

***************************************************
 Ralph Niederberger
 Juelich Supercomputing Centre
 Institute for Advanced Simulation

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 Fax:    +49 2461 61-6656
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 JSC is the coordinator of the
 John von Neumann Institute for Computing
 and member of the
 Gauss Centre for Supercomputing
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