fbaube@NOTE.NSF.GOV ("F.Baube") (12/15/88)
Leif Andrew Rump <mcvax!enea!dkuug!ambush!ambone!leif>:
> .. so ISDN could be the system of tomorrow (more or less literally!)
Okay, but how much agreement is there on what *broadband* ISDN
should look like ?
#include <disclaimer.h>leif@ambone.UUCP (Leif Andrew Rump) (12/24/88)
fbaube@NOTE.NSF.GOV ("F.Baube") writes: >Leif Andrew Rump <mcvax!enea!dkuug!ambush!ambone!leif>: >> .. so ISDN could be the system of tomorrow (more or less literally!) >Okay, but how much agreement is there on what *broadband* ISDN >should look like ? As far as I remember there is already a definition on how anything from 16K bit datacomunication through voice/picture (64K bit) to television/HIFI and on
jbn@glacier.STANFORD.EDU (John B. Nagle) (12/26/88)
ISDN may be an idea whose time has passed. Optical networks are coming, and it's very possible that delivery of TV signals will be over the same medium used for voice and data, especially into homes. ISDN offers only 64Kb data, and with modems at 14Kb, the benefits of rewiring the entire phone plant for ISDN are marginal, especially since the cutover to optical is already beginning. John Nagle
bobk@boulder.Colorado.EDU (Bob Kinne) (12/28/88)
In article <17941@glacier.STANFORD.EDU> jbn@glacier.UUCP (John B. Nagle) writes: > > ISDN may be an idea whose time has passed. Optical networks are >coming, and it's very possible that delivery of TV signals will be over >the same medium used for voice and data, especially into homes. ISDN >offers only 64Kb data, and with modems at 14Kb, the benefits of rewiring >the entire phone plant for ISDN are marginal, especially since the cutover >to optical is already beginning. I'm not an ISDN fan, but there is far more to ISDN than 64k data lines. ISDN is now completely defined to T1 rates (1.544Mb/s in US, 2.048 in Europe). Work is now being done on broadband versions of ISDN, and yes, future versions will employ optical networks and support SONET interfaces. It is also not true that ISDN requires rewiring the entire phone plant. Much of the defined ISDN function runs on existing plant. The significant changes to date are mostly in the switches and in incorporating out of band signalling.
sl@van-bc.UUCP (pri=-10 Stuart Lynne) (12/28/88)
In article <17941@glacier.STANFORD.EDU> jbn@glacier.UUCP (John B. Nagle) writes: > > ISDN may be an idea whose time has passed. Optical networks are >coming, and it's very possible that delivery of TV signals will be over >the same medium used for voice and data, especially into homes. ISDN >offers only 64Kb data, and with modems at 14Kb, the benefits of rewiring >the entire phone plant for ISDN are marginal, especially since the cutover >to optical is already beginning. No, ISDN is designed to take advantage of the current wiring. The phone companies biggest asset is copper, and ISDN allows them to extend the use of the current installed base significantly, simply by replacing the analog devices at each end of a connection with digital devices. There is no way that the phone companies would ever consider replacing all that copper in the ground except over a very extended period. ISDN allows them use what they have, to provide many new services without replacing the wiring. -- Stuart.Lynne@wimsey.bc.ca {ubc-cs,uunet}!van-bc!sl Vancouver,BC,604-937-7532
edm@nwnexus.WA.COM (Ed Morin) (12/30/88)
In article <17941@glacier.STANFORD.EDU> jbn@glacier.UUCP (John B. Nagle) writes: > > the benefits of rewiring the entire phone plant for ISDN are marginal, > I thought one of the prime advantages of ISDN was that it did *not* require rewiring! Yes, I realize that CO and CPE often needs to be replaced, but at least the cable plant doesn't need to be changed... -- Ed Morin Northwest Nexus Inc. "Unix Public Access for the Masses!" edm@nwnexus.WA.COM
fbaube@NOTE.NSF.GOV ("F.Baube") (12/31/88)
As I understand it, narrowband "basic service" 2B+D ISDN does *not* require *any* new cabling. Even if this is so, I have also heard that not only are *new* installations using fiber, but also that in some cases, perfectly serviceable in-place copper wiring is being yanked and replaced by fiber, both to free up tight cabling space *and* to capture the scrap value of the copper. Such a trend would accelerate the move away from the bandwidth restrictions imposed by copper, facilitating the growth of a base of potential customers for broadband ISDN, customers that would not need further investment in new cabling. Is this an (at least superficially) correct understanding of the economics involved ?
jbn@glacier.STANFORD.EDU (John B. Nagle) (12/31/88)
After replacing the CO and the station equipment, all you get is 56Kb.
This was a hot idea when dial-up modems ran at 1200 baud, tops, but with
performance at 14Kb, and modems getting cheaper every month, the pressure
is down for more bandwidth over the dial-up system. Especially if the
line charges for ISDN connections exceed those for voice connections.
Check into the GTE fibre-optic test in Covina, CA, where a switched
fibre-optic network is being installed. Home customers can call up and
ask for a video feed from any available source, including a farm of VCRs.
Two-way video connections are available - this is full-bandwidth color
TV videophones, at last. That is the future - not ISDN.
John Nagle