Wednesday, November 12, 2008

Internet Measurement

This is probably the densest paper we've read. It's an in-depth analysis of TCP's behavior. It attempts to analyze the assumptions we have when building TCP, just as the network's infrequent reordering to the packet error rate. It's an immense work.

On a note, I'm going to start a list of worst project/protocol names. New on the list: SACK. SACKs are not new to me, but this is a new list and I've recently been reminded of it.

The usual complaints apply to this work. It's old, we're not sure how relevant the findings are to the modern internet. There were many reorderings and bursty losses due to routers updating their routes. This is presumably less likely now. Follow-on work would be great to read, as it would show what changes were implemented in reaction to these finding (not many I'd wager).

I really like these deep, measurement papers. There's so much nonsense about building a system when there's such a light understanding of the problem you're trying to solve. This work likely led to tens of future projects for exactly that reason. There are plenty of engineers in systems, we need more analysis.

Particularly, I want more social science techniques in systems and networking. This is probably a deeper analysis of user cases. We build so many technologies that are solving problems that don't exist. They get into SIGCOMM, put in a binder and on a CV, and that's it. Though, to be fair, that may just be academic problem...

Anyhow, I feel like I had something else of value to say about this work, but I can't remember. Perhaps I'll update once I remember.

2 comments:

Randy H. Katz said...

SACK = Selective Acknowledgement. What is wrong with that as a name or acronym?

Paxson is about the only researcher to have ever done such a massive performance study (and he wrote a 300+ page dissertation as a result), so I think his insights about measurements are still valuable, even if the specific measurements may yield different results in the Modern Internet (with better tuned routing protocols, different TCP implementations, etc.).

Yanpei Chen said...

A kindred spirit on the value of social science :)