SUMMARY: What are/is ATM (besides Automatic Teller Machines)

Date: Wed May 19 1993 - 18:06:03 CDT

I got replies to my original query (included below). They pretty much said the
same thing, some replies more detailed than others.
I'll attempt to paraphrase the replies and trim duplicates.

I did receive a couple of folks who pointed out that this topic
is not appropriate for this group. Maybe thay are right. I think it
would be one which might fall into the nebulous zone. However there were
*several* folks who wanted to know more about it. So here's the SUMMARY.
Anonymous ftp sites are listed at the end.

ATM ==> Asynchronous Transfer Mode (A protocol for broadband communications.)
ATM is the latest and greatest in switch/communication technology.
It is not yet a proven technology on any platform yet.

The available bandwidth of ATM can be a high as 1.55Gb/s at
the workstation desk top
ATM uses a 53 octet datagram. 5 octets for addressing, 48 for data
ATM is well suited to multimedia applications because since the
cell size is fixed, it can transfer voice and image simultaneously
or asynchronously such that the application receives both at the same
It's sheer speed alone would qualify it for wide distribution.
As you can tell by looking at the standardization of FDDI which has
been available for quite some time and still not widely accepted,
ATM may be 3 to 5 years away before we see it commercialized. The
vendors like Cisco, Synpotics etc. are working hard to mass produce
the hardware much sooner. Sun Microsystems I think is on the
ATM consortium.
Routers will most likely benefit sooner than desktops for 2 reasons.
The technology is expensive at the moment.
Router protocols seem to be well suited for transfer across
LAN's and WAN's

ATM is a new method/technology for high
speed network communication (45Mbps-~150Mbps) ideally over grade 3
wiring (also can be implemented over STP, grade5, fibre). it is
constant length cell based as opposed to variable lengeth packets. it
can be local or switched. It can replace existing local and wide-area
network segments (once wide-area providers are available).

ATM = "Asynchronous Transfer Mode". It's a communication architecture
based on switching or relaying small fixed-length packets called cells.
CCITT has adopted it as part of the B-ISDN standard. (I guess the ISDN
currently supported on sparcstations is the A variety.)
ATM is also the architecture which will underlie gigabit-speed networks.
If you're a member of IEEE, they have some tutorials on it.

ATM stands for Asynchronous Transfer Mode, a short-packet protocol based on individual connections
and it is contending with Fiber Distributied Data Interface (FDDI) to be the 21st century standard
for local area networks. There is a great article in the April 1, 1993 Datamation magazine which
describes the pros and cons of ATM and FDDI.

Information Week April 19th '93 issue - A journal for information mgmt.
the article is "Breaking Down The Walls"

ATM means Asynchronous Transfer Mode. It is a CCITT standard, not
a product, although there are many ATM products. It is the transfer mode
chosen for the Broadband ISDN. The usenet group comp.dcom.cell-relay
deals mostly with ATM, you might want to check it. Apart from the
standard documents (I don't know the references by heart, sorry), there is
a good introductory book: "Asynchronous Transfer Mode - solution for
broadband ISDN", by Martin de Prycker (Ellis Horwood, ISBN 0-13-053513-3).

Sun & Synoptics just announce a ATM board for the SBus. It is expensive
but so it FDDI. FDDI's current advantange is that aside from the system
hard/software all you need is the cables. Its disadvantage it that it
really does not work well on copper and it face a challenge from 100Mbs
ethernet. ATM is a packet switch technology, similar to a PBX or even
ISDN. Its advantage is that there is copper at 100Mbs, and in the
future it looks as though it can go to 600Mbs though that will probably
have to be restricted to fiber. A big disadvantage and a big increase
in per station cost is that you need a central hub. Though there are
configurations that reduce this - you don't necessarially need a hub that
supports every system as an ATM enity. Anyway there are not many of these
hubs so there is not much competition so the prices are high. Synoptics
has one - perhaps the Yankee Group sells one too?

ATM = asynchronous transfer mode. it's a network technology of
the future. ATM offers predictive delivery of data, so you can
send voice/video/audio together. it's fast -- 155 Mbit or 622 Mbit/sec
initially, with support for SONET and Gbyte/sec nets. it uses
some stat mux theory to balance out data in "payloads" -- think
of ATM as sending a stream of large bytes, rather than small
packets (the cell size is about 50-60 bytes, i forget the exact number).
 retix, synoptics, netrix, newbridge, etc are all heavily invested
 in ATM. check out UNIX review from oct or nov -- there was an excellent
 set of articles on what ATM is and how some companies (like retix)
 are doing in building ATM switches

Anonymous FTP sites: (file/directory pub/cell-relay)

Thanks to: (Andy Hooper) (Bear)
Robert E. Toense <> (Joel Shandelman) (Ed Arnold)
Larry J. Miller *** E-mail: (John D Schneider) John says
        I don't have an answer to your question, but I just had to answer anyway.
        You received a brochure called: "Demystifying ATM, The Users Perspective",
        and after reading it you still don't even know what ATM is? Must be some
                        Good point John. Anil Katakam
Tim Chan <> (Joaquim Fernando Soares) (John Justin Hough)
David Fetrow <>
Rodney Campbell <>
Timothy G. Smith - Special Projects <> (Greg Jumper) (Hal Stern - NE Area Systems Engineer) (Leon Koll) (Martin Kelly)
Rogerio Rocha - DI - BVL <>
Patrick O'Callaghan <> (Julian Dryden) (Ray Schnitzler) (Aditya Talwar)
archer!banshee! (Mike Steadman)
Christian Lawrence <>
"Scott Gargash" <>



==>Hi all
==>I need to get information on what an ATM is. Its something to do with integr
==>networks. Thats all I know of. It might be a commercial product. I received
==>a brochure
==>from the Yankee Group "Demystifying ATM, The Users Perspective". If it is a
==>commercial product,
==>does anyone have any experience with it? Could you shed any light on this?
==>Thanks, and I will summarize.
==> -Vispi Dumasia


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