Network model: The Original: FoF

You can imagine the original model of the Gnutella network as friends phoning each other to get information. One asks five others, each of whom asks 5 others and so on. After the first step the number of people reached is 5, after the second it is 25, after the 5th 3125, after the 7th 78,125 and after the 14th about 6.1 billion. That would be enough to reach every human being on this planet. The original Gnutella used 7 steps (called HTL: Hops To Live).

A Problem with this model (among others) is that you have to be a part of the clique before you can use it. There have been several ideas to solve this problem. I will show you three of them.

Getting in: The first way: Pong-Caching

Pong Caching means that the node (aka you) asks its friends who their friends are. It means your friends introduce you to their friends, especially friends whom they value highly, and you write all new adresses in your phone-book, so you know whom to phone when your original friends are on holiday (Somehow like being at a continous cocktail party). It is easy and has the advantage of giving you very reliable contacts, but there is no way of getting into the network without knowing at least one contact who is already in the net. That means you can always get back in, but won't be able to connect if you never did before.

Getting in: The second way: Remember who answers

The second way is really simple. When one of your 5 friends calls back to say Smith (whom you didn't know before) knows something, you note his number. When you call him the next time as one of your five direct contacts, the chance is greater that you will get your information more quickly, because he will likely have friends who have similar interests to you (where else should he have gotten the information?), and those are more likely to have your information than randomly picked persons (at least when you ask about something similar to your last question). The drawback is that those contacts might not be at home often, so it might be that you find a contact with great knowledge, but whom you'll never be able to reach again. Still no way of getting in the first time. And now we get to one of the recent developements in Gnutella: GWebCaches. I will discuss them in the next part.

To learn more about about Gnutella visit http://gnufu.net - Gnutella For Users

This FAQ was contributed from http://gnufu.net - Gnutella For Users