perfSONAR User Q&A and Other Discussion

[Dale Smith <>]

On 3/11/15 1:58 PM, Brian McNally wrote:
> I'm attempting to locate perfSONAR/bwctl endpoints in the US that are
> open for public UDP tests. It seems like most sites allow TCP tests but
> deny UDP tests. Why is this? Could someone recommend some UDP endpoints
> I might be able to connect to?

I might point out that the reason that people don't offer public UDP
tests is that unlike TCP, UDP is not a "good citizen" and doesn't back
off in the face of congestion.  There was a poster earlier today that
talked about bwctl tests that would oversubscribe a link.  He was using
TCP-based tests, and since it is TCP-based, the TCP bwctl tests will be
a "good citizen" and will back off in the face of congestion and will
play nice with existing utilization of an over-subscribed link.  UDP
will not and will absolutely over-run your infrastructure and be very
disruptive to normal usage of your network.  You need to be very
cautious in using UDP-based testing or you will have very unhappy users.

 -Dale