Safe and easy test of managed Intrusion Detection Service

Safe and easy test of managed Intrusion Detection Service

I would like to periodically test the managed IDS solution for a client,
to make sure they detect and alert the client in a timely fashion. The IDS
company is only monitoring the perimeter firewalls and WAN communications
(site-to-site).
I am looking for some good ways to perform such a test without actually
introducing a real threat into the environment.
One thing I can think of is to do some port scans over the WAN links,
which I believe they should detect as long as I am not too low-and-slow. I
could also download the EICAR test virus, but it is not likely to generate
a security incident, since it is well known to be a test.
The environment is a mix of Windows and Linux.
Some good suggestions of other actions I could perform?