phil@amd70.UUCP (Phil Ngai) (06/12/84)
Has anyone ever heard of cheapernet? What do you know about it and
what do you think of it? Either mail or followups would be appreciated.
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Phil Ngai (408) 982-6825 {ucbvax,decwrl,ihnp4,allegra,intelca}!amd70!philsunny@sun.uucp (Sunny Kirsten) (06/13/84)
Greetings, fans of cheapernet: *A* form of cheapernet is espoused quite successfully by 3Com. Wheras Ethernet is your big half inch inflexible expensive cable conceived in the early days of Xerox' Ethernet (back in the 3MHz days, remember?), where the idea was to pre-wire a building with the cable, and provide transceivers built into the wall, so that each office would have a couple "information outlets", the now Dec-Intel-Xerox standard transceiver/controller interface, Cheapernet is composed of thinner, cheaper flexible cable (RG-58/AU), and the concept of building Ethernet transceivers (cheaper smaller VLSI ones) into equipment (a la 3Com's IE for the *ugh* IBM PC) so that no one has to pay big bucks for "real" transceivers. If this is done correctly, as by 3Com, there is direct plug compatibility with "real" Ethernet. Typically, in this world, connectors are BNC rather than the traditional Ethernet connectors. The only drawback of this situation, is that the thinner Ether is more "lossy", so that you can only go half the distance of cable before you need a repeater. If you're interested in 3Com's cheapernet, contact them at (415)961-9602, POB7390, Mtn. View, CA 94039. Tell 'em Sunny sent ya'. Another form of cheaper net (cheapernet *might* be trademarked?) is to drop the operational frequency down from 10Mhz to around 1Mhz, go INcompatible with "real" ethernet (bad idea) and get your cost down with cheaper lower frequency transceivers, maybe also cost reduction with VLSI. What do I think of cheapernet? If it's compatible with "real" Ethernet, as 3Com's is, I think it's better than Ethernet, and I expect this new standard (cheap thin flexible cable hooked up with BNC) to replace, in the long run, the expensive thick inflexible tapped-transceiver version. The nice thing about this approach is total compatibility with Ethernet both electrically and logically, so you can extend your ethernet across the street with Ungermann-Bass/Seicor/Fiberlan's fiber-optic (and expensive) Ethernet, and run cheap cables and transceivers within buildings. You get a big building, and you'll need some repeaters, especially since you'll use more footage of cheapernet, actually running by EACH node, rather than lots of expensive multiconductor transceiver cable dropping from transceivers placed at the site of the thick cable. (Xerox' repeaters work fine on cheapernet, by my actual experience). With the advent of VLSI ethernet controllers, the main cost remains in the transceiver. When THAT finally goes VLSI, Ethernet will *truly* be cheap. But don't hold your breath yet...analog isn't trivial. [ucbvax,decvax,ihnp4]!sun!sunny (Sunny Kirsten of Sun Microsystems)
julian@deepthot.UUCP (Julian Davies) (06/15/84)
At a presentation here by 3Com, it was explained that the 'thin cable' is lossier by a factor of 3, not 2, so that 1 foot of thin cable should be counted as 3 feet of thick-cable equivalent. A system with thick cable and only 3Com external transceivers can go to 1000m, so a thin cable segment can only go to 300m. However, the two can be combined in one 'segment' up to the 1000m "thick equivalent", provided there are only a few thickness transitions. Thick cable with less controlled transceivers is limited to 500m, they said. Another thing I learned and hadn't appreciated before is that the 'repeater' joining two cable segments is a bit-level repeater, not a frame-level buffering repeater, so there is an upper limit if 2500m and two repeaters between any pair of transceivers in a single network made from several segments. and *that* limit 2500m includes the connecting cables used at repeaters or in fibre-optic repeater connections. one can go beyond that limit if a full-fledged gateway buffering and retransmiting frames is used. Julian davies university of Western Ontario
rpw3@fortune.UUCP (06/20/84)
#R:amd70:-472500:fortune:5900025:000:1650
fortune!rpw3 Jun 19 19:47:00 1984
1. 3Com's RG-58/U version is called "Thin Ethernet", not "cheapernet".
2. Someone will surely attempt to trademark "cheapernet", but they will
won't succeed. The generic term "cheapernet" has been used in public
by me and by others around me for at least five (5) years to mean any
form of Ethernet repeater-compatible network that was "cheaper" (that
is, the packet format and the bit rate were the same, but the logic
levels, encoding, and collision-detection method could differ).
3. We have also used the term "cheapo net" to mean a cheapernet that used
inexpensive plastic fiber optics (such as the H-P "Snap-In" link or
the Molex stuff) from the station to a repeater/multiplexer.
(get it? cheap-o-net! *gag* ;-} )
(By comparison, Codenol's Ethernet-compatible fibernet is "expensiv-o-net"?)
4. Some people (AMD? Intel?) have also been using cheapernet to mean a slower
bit rate, such as 1Mb/s, but I don't buy that usage.
There are many variations on cheapernets, from (nearly) full electrical
compatibility and interoperability (such as 3Com Thin Ethernet), to
transceiver-cable multiplexers (DEC's DELNI or TCL's MultiStation), to
other schemes (such as TTL "Ethernet down the backplane"). If we want to
widen the term "cheapernet" to exclude Ethernet repeater compatibility,
then maybe we should reserve "cheaprenet" (with the British/Continental "-re-")
to continue to mean the 10Mb/s repeaterable version. (Maybe CheaprEnet??)
Rob Warnock
UUCP: {ihnp4,ucbvax!amd70,hpda,harpo,sri-unix,allegra}!fortune!rpw3
DDD: (415)595-8444
USPS: Fortune Systems Corp, 101 Twin Dolphin Drive, Redwood City, CA 94065plb@omsvax.UUCP (Phil Barrett) (06/21/84)
To reduce the cost of ether, Intel sells (used to sell??) something called the "Intellink". This is a box that turns one ether tap into 8. That is, the cost of one transeiver is spread out over 8 systems. In addition, the link box DOESN'T NEED TO BE HOOKED UP TO A NET if you want to have a vlan (very local area net) with out the big thick cable (or any cable at all). The link works with standard ether net controllers so you don't get any cost savings there but transievers ain't cheap (right Phil?). I think the max distance is 50 M (100M total). I don't know: the cost availability limitations So call your neighborhood Intel Sales office and don't tell 'em I sent you. The opinions expressed are strictly my own and should not be construed as a blatant instance of crass commercialism. However, if everybody bought one I could get a raise so I can pay for my mothers heart transplant and my baby's dialysis machine. :-) Phil Barrett Intel Corp Integrated Systems Operation tektronix!ogcvax!omsvax!plb hplabs!intelca!omsvax!plb
phil@amd70.UUCP (Phil Ngai) (07/04/84)
Most of the authoritative people at AMD (as opposed to Joe Random engineer)
seem to mean a 10 Megabit/sec network when they say cheapernet.
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Phil Ngai (408) 982-6825 {ucbvax,decwrl,ihnp4,allegra,intelca}!amd70!phil