The answer of course is that you DON'T have to assume that s=MSS here, you can use the real packet size. So am I missing something in your question?
If s cancels out (bc you are designing a packets/sec implementation), then it doesn't matter what s is. Set it to MSS, set it to 1, who cares? The packet/sec rate you get out of the throughput equation will be the same, no?
As I read RFC4342 I can't implement a packets per second implementation directly - there are several options but packets per second is not one of them. The mathematical equation allows it as you seem to agree by your first statement. The RFC doesn't. If we track the average packet size it works but then that is a whole lot more complex code to achieve exactly the same thing.
Eddie
Ian -- Ian McDonald Web: http://wand.net.nz/~iam4 Blog: http://imcdnzl.blogspot.com WAND Network Research Group Department of Computer Science University of Waikato New Zealand