Bandwidth is not related to EITHER the number of subscribers OR the number of people logged on! It is NOT dedicated bandwidth!
The bandwidth in use is determined by the instantaneous demand by all subscribers on a node, limited by the maximum transmission rate of the node. (26Mbit/sec in the case of @Home in San Diego.)
It's very similar to an Ethernet network. You are assuming a model closer to that of a token ring network, where everybody who is connected gets a dedicated "slot". It doesn't work that way.
If I, say, request a web page, the web page is sent to me. (duh). I use whatever bandwidth is needed to send the request and receive the page. (On separate upstream and downstream streams.) If I DON'T make any requests, I am NOT using any bandwith.
If I am the only person using the system, (say, at an odd hour) I can actually get the full system bandwidth. (Though I've never seen this, I've gotten pretty healthy bandwidths - 5-7Mbit/sec - you can get more if you do multiple downloads simultaneously.)
The bandwidth in use, and bandwidth available to each user, is determined solely by current demand. Period.
By the way, there would never be 1000 subscribers on a node, at least on @Home. Cox has told me that they will go to 500 "homes passed" per node eventually. Right now, they are built at 1000. That is NOT 1000 subscribers/node, but 1000 "homes passed" literally. If they get 20% penetration, there would be 200 homes/node.
Considering that most companies of 200 people typically would use no more than a T-1 (1.5Mbit/sec), I think our 26Mbit/sec is going to be quite acceptable for the forseeable future. |
