At 01:54 PM 7/18/96 -0700, you wrote: --- all the following points are based on swiss circumstances, they may not apply to US ---
point to point circuits are more efficiently handled by circuit switching rather than packet switching networks. Nicholas Negroponte wrote an interesting piece about asynchronous vs synchronous, I believe it is in his book "Being Digital."
Well, from a users point of view, sending packet data over a packet mode bearer service is more efficient (and cheaper). An interesting developement in this direction is the PMBS-A/B modes of ISDN (packet switching to the public switch). The existance of this service suggests its usability.
ADSL is an interesting attempt at digital telephony but expensive and basically would mean replacing existing central office switches. (backbone bandwidth)
We have a well developed DQDB-MAN and ATM net around, and bandwidth is available (and getting cheaper by the minute). Currently, a onetime investment of around $2500 per client is necessary to provide >5MBit/s transfer volume (via the cable TV networks or the existing broadband networks)
In a packet network you have to either dedicate a portion of the bandwidth for a synchronous circuit, or you have to have a very fast network and use very small packets (ATM), expensive either way.
Not if you have a dedicated packet switching network for asynchronous packet transfer only. If you use it for both you don't have to have a very fast network, you have to have a network with predictable and constant packet delay. (that's not the same as fast!)
A single central office has many times the bandwidth of the widest part of the internet, and the average state has hundreds of CO's. If even a small portion of the Internets current users tried placing a call things would grind to a halt. A huge increase in the number of backbones and their bandwidth would solve this, but who will pay the bill?
I guess Internet-telephony is one of the bandwidth killers.
TANSTAAFL
Sometime ago the discussion was on the cost of laying new fiber, may I suggest the realworld heuristic of "a million dollars a mile."
There are of course a lot of alternatives: - Existing wiring (5 MBit/s over 6 copper wires is possible) - Usage of the cable networks - Radio transmissions (RITL - radio in the loop) - Satellite transmissions
Please note I am not trying to make fun of anyone personnally, I am in the words of Jubal Harshaw "heaping scorn upon an inexcuseably silly idea, a practice I shall always follow."
Neither am I, but isn't anyone? ----------< fate favors the prepared mind >---------- Remo Pini Fon 1: +41 1 350 28 82 mailto:rp@rpini.com Fon 2: +41 1 465 31 90 http://www.rpini.com/remopini/ Fax: +41 1 350 28 84 soon:PGP: http://www.rpini.com/remopini/rpcrypto.html --------< words are what reality is made of >--------