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Mathematical Analysis of Gnutella
jrp2 sent in a paper written by one of Napster's founding engineers. It is
a mathematical evaluation of Gnutella discussing
why the network won't be able to scale up to any reasonable size. I
have been impressed with Gnutella in the past, and have wondered along
these same lines in the past.
Yes, but..
It's sort of like calculating the maximum hull speed for steam ships crossing the Atlantic Ocean and saying there is a theoretical maximum speed to intercontinental travel. Then someone comes along and invents airplanes.
Gnutella will mutate and evolve, and will at somepoint in the future be replaced by something better when it starts to fall over.
The demand for Ms. Spears and the Backstreet Boys is just too damn strong for things to stand still.
I enjoyed that this post was next to the announcement that of the new-and-not-so-improved preview of Napster was out..
~.~
I'm a peripheral visionary.
In theory, a true Peer-to-Peer file transfer network would exist in a decentralized fashion where you would never have to query a central host for routing or file availability. Napster requires you to route through one of the Napster servers for information. Even introducing Napigator still doesn't alter the Napster model because all it does is allow you to route through a different central host. It seems that all Napster did was integrate a search engine and nameserving into one element (coming from only one provider).
This isn't to knock the accomplishments of Napster, it was certainly an original idea to incorporate these areas and provide a GUI access client to boot. But it is apparent that Napster developers weren't all that revolutionary in their thinking either.
The suggestion of true P2P is revolutionary, and the perfect implementation (should it ever arrive) will also be revolutionary. But the Napster model is no different than everyone providing their MP3 list to a website who maintains a list of links on where to download MP3s. Napster simply automated this process. Napster is no more P2P than any TCP/IP connection not operated through a proxy.
Is http P2P? I'm talking directly to another system, and there is no moderator/mediator. Normally, I have to find out about that system from a 3rd party (e.g. a search engine) -- just like someone obtains a list of links from Napster.
True, I'm being no better than the author of the original article; because I too am offering no solutions. I'm just holding out hope for true P2P in the future.
As I pointed out last time this was posted, this article is basically 100% FUD. Yes, the amount of traffic goes up. And no, gnutella doesn't scale very well. But the author goes out of his way to make the problem look worse than it actually is. You see, the article only computes the total amount of traffic in the entire network. A number which is both huge and meaningless. You see, by this math, if I send a packet somewhere and it takes 10 hops, well, thats like sending 10 packets!
At the end of the paper, the author coughs up the big scary number of 63GBps of traffic in the Gnutella network when the nodes each have 8 connections and are using a TTL of 8. Wow! That's a lot of traffic. That certainly isn't scaling! Well, what the author never points out is that, by his own math, the network has 7,686,400 users at this point! When we divide up the total traffic among all of those network links, we get a different view. If you do the math you discover that this is a whopping 72Kbps! Oh no! It's the end of the world! Well, no, it's not. True, it's more than a modem can handle. But it's well within the reach of most cable modem connections. Given that your computer is being expected to handle the search requests of over 7 million other people, it's not that much traffic.
Don't get me wrong, I agree that Gnutella doesn't scale all that well. But this paper is just plain FUD. The only number that really matters to users is the total bandwidth load on their pipe. By carefully avoiding that number, which isn't very big and scary at all, the auther is clearly lying by ommision. Given all of the real problems networks like Gnutella encounter, it isn't interesting to read this sort of drivel. Why don't we drag out Mathmatical and model how much bandwidth Napster wastes by transmitting the names of all the files being shared even though most of them will never get searched for. Hmmm. lets assume 7,000,000 users. Let's assume that they each share 1000 files with an average filename length of 32 characters. Why, that's 224 Gigabytes of data, and we haven't even done any searches yet! Cleary, Napster doesn't scale. Ugh. This guy might know how to use Mathematica, but I still suspect he worked in the Marketing department. With the same guys who will tell you about their 200Mbps fast ethernet.