"A pun of X" or "a pun based upon X"?

In the following phrase, I am unsure of my usage of the word "of".

The protocol name µDP (pronounced mew-dee-pee) is a pun of multicast UDP.

Is it said that something is a pun of something else, or is it perhaps instead the case that a pun is based upon something else?

Interesting comments aside, the answer to your question as to how to mark the relationship between the pun and the punned seems to be clearly "pun on". Here is an ngram analysis comparing the usage of "pun of", "pun on" and "pun based on" and "pun on" is the clearly dominant phraseology.

So:

µDP is a pun on UDP.

Of course any of the three would be readily understood, but I think this analysis clearly shows the idiom.

And, as my dear departed father used to say, jokes based on one word sounding like another are very punny indeed.