| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 382.1 | | KONING::KONING | Paul Koning, NI1D | Thu Oct 31 1991 13:59 | 19 |
| I don't think so.
You can certainly transmit voice (packetized) over FDDI, or for that matter
over any other datalink that's fast enough. We've demonstrated that with
our multimedia work. But I wouldn't recommend trying to use FDDI as a
voice backbone. For one thing, the cost of attachment makes that a poor
idea.
What are they trying to do, or to put it differently, what are they trying
to save? Note that there is no significant cost difference between running
a cable with one fiber pair and one with 12 or 24. Indeed, we recommend
that you run fairly substantial cables in your major wire runs; see the
Fiber Optic sections of the DECconnect documentation. So if they are running
fiber now, the sensible solution is to run multiple pairs, and install
PBX equipment that can use the fiber (or PBXs plus outboard copper to fiber
converters). But those fibers would not be running FDDI; rather, they'd
be something like T1, or T3, or whatever a PBX finds most convenient.
paul
|
| 382.2 | TNX | VAXRIO::ROLF | Vaporware Design Specialist | Thu Oct 31 1991 15:41 | 3 |
| Thanks Paul, you confirmed my feelings!
Rolf
|
| 382.3 | FDDI-II ? | BSS::C_OUIMETTE | Holographic Interference Repository | Thu Oct 31 1991 16:39 | 12 |
| A side question:
Whatever became of "FDDI-II"? As memory serves, this was s standard
promoted by Telco, which allowed "Isochronous" traffic, or guaranteed
access time permitting 1 byte of data to be sent every 125 us, thus
permitting a 64Kb voice channel to be mux'd onto the fiber...
Did this ever become a reality? Or do I remember incorrectly?
chuck
|
| 382.4 | | KONING::KONING | Paul Koning, NI1D | Thu Oct 31 1991 19:18 | 13 |
| Pieces of FDDI-II exist on paper. No chips have been seen yet, let alone
systems. It's massively complex (far more so than FDDI, which is already
complex enough). SMT-2, which it needs, hasn't been started yet, and
various other pieces are also incomplete. Finally, in spite of its name,
it's totally incompatible with FDDI and really has very little in common
with it.
If it existed, FDDI-II could perhaps be used for this purpose, but because
of its complexity would be less reliable and more expensive than a solution
tailored for the job. We believe that FDDI-II is a solution (or someday
will be) in search of a problem.
paul
|
| 382.5 | The interest is elsewhere | DELNI::GOLDSTEIN | Networks designed while-u-wait | Fri Nov 01 1991 12:39 | 8 |
| And the telephone industry isn't too interested in FDDI-II either. The
Metrpolitan Area Network project (802.6) has a protocol of its own
(DQDB) which allows voice and high-speed data to share a physical
medium. It's also not worthwhile for short-haul use, and not quite
complete yet (voice support is being developed), but it's also not
FDDI-II.
Sometimes multiplexing isn't worth it.
|