UDP Testing Procedures

I'm writing a suite of application components which will eventually be a part of a game engine. I just finished working on my threading system and am switching over to testing multithreaded network functionality with an emphasis on UDP.

If I was making a TCP server the first thing I would test is HTTP: Send a HTTP request to www.google.com, echo the reply to stdout, hooray.

What's a common UDP protocol that I can test UDP internet connectivity with? I can't think of any off the top 开发者_Python百科of my head. DNS?

Wikipedia list of established TCP and UDP ports and protocols

NTP (Network Time Protocol, port 123) might be something to test.

http://www.netfor2.com/dns.htm

This is kind of what I am looking for.

Are there any other protocols over UDP which are even more simple (focus on structure of request packet)?