perfSONAR User Q&A and Other Discussion

[Alan Whinery <>]

On 3/11/2015 8:27 AM, Pol Llovet wrote:
> I have a laptop that I am using to do point in time tests of bandwidth and
> latency in various labs around our campus.  This is mostly to have an
> "apples to apples" test (or at least the closest thing to it I can get).
>
> However, my bandwidth tests are coming up at close to the theoretical
> maximum for TCP/IP over the switch port speed. This isn't really what the
> users are seeing.  Does anyone know of flags I could send to bwctl or owamp
> to more accurately represent different types of traffic (video streams,
> loading a GIS file, rsyncing a giant image or tgz, I/O on lots of small
> files, etc).
>
> Thanks for your help,
>
> Pol Llovet
>

If you want to emulate what users are seeing, you're probably better off
doing what the users are doing, than trying to emulate it with iperf or
nuttcp, etc. I keep a 2 GB file on a well-connected server, with a
fairly fast disk. For a more "real world" test, I tell people to
download that file, which will be subject to more of the pressures and
influences that "real" traffic is subject to.

Or alternately, if you want to match users, have users do iperf or
nuttcp tests. but memory-to-memory throughput tester tests are most
often not going to compare easily with user activity. Iperf/nuttcp show
you what the network can do without the other constraints you
mentioned.  Users have slow disks, constrained network stacks, other
challenges.