haas@wasatch.UUCP (Walt Haas) (02/08/89)
I seem to recall reading that somebody made a "null ethernet" box, that is a box that had two DB15s so that you could create a trivial Ethernet without buying transceivers or a DELNI. I can't find the reference - does anybody out there know of such a thing? Thanks -- Walt Haas haas@cs.utah.edu utah-cs!haas
kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) (02/09/89)
In article <1064@wasatch.UUCP> haas@wasatch.UUCP (Walt Haas) writes: >I seem to recall reading that somebody made a "null ethernet" box, >that is a box that had two DB15s so that you could create a trivial >Ethernet without buying transceivers or a DELNI. I can't find the >reference - does anybody out there know of such a thing? > >Thanks -- Walt Haas haas@cs.utah.edu utah-cs!haas American Network Connections makes a two port delni or "ethernet null modem". They are in Sunnyvale at (408) 737-1511. Someone reported flaky behaviour using this product as a null modem. I wish I could remember who it was. Take this warning with a grain of salt, I do not wish to denegrate ANC without justification. I decided there just wasn't enough price differential between a two port and an eight port delni to justify stocking and supporting two products from two vendors. We use Cabletron transceivers and delni's. There are multi-ports where you can buy the interfaces one or two at a time. Would that save a substantial amount of money? I don't think it's worth the trouble. On another note, there is now a fiber optic transceiver cable extender product on the market (at least I know of *one*). This is a nifty item when you want to install one node a long way away from a delni or transceiver port without getting into a f/o multiport concentrator or kluding in a f/o repeater (wrong sex connector on one end). Not sure what the delay budget is. Kent England, Boston University
haas@wasatch.UUCP (Walt Haas) (02/09/89)
In article <27748@bu-cs.BU.EDU>, kwe@bu-cs.BU.EDU (kwe@bu-it.bu.edu (Kent W. England)) writes: > American Network Connections makes a two port delni or > "ethernet null modem". Thanks to Kent and others for this information. They apparently moved from Sunnyvale to San Jose, but the phone number there has been disconnected (although directory assistance still give it out). Does anybody know what's going on with these guys? Thanks again -- Walt Haas haas@cs.utah.edu utah-cs!haas
fosterm@ogccse.ogc.edu (Mark Foster) (02/10/89)
In article <27748@bu-cs.BU.EDU> kwe@buit13.bu.edu (Kent England): > > Someone reported flaky behaviour using this product as a null >modem. Yeah. We had severe problems with them when they were used (get this) with both ports connected! ANC sent a nice note recalling certain serial nr.s. They happily exchanged ours but the behavior was the same (lots of jamming and dropped packets during activity on both ports). I now use them for "hot spares" for our single port transceivers, when needed. In article <1070@wasatch.UUCP> haas@cs.utah.edu (Walt Haas): > but the phone number there has been disconnected >(although directory assistance still give it out). Does anybody know >what's going on with these guys? I suspect that they couldn't get their product problems resolved, and being a young startup, dissolved quietly. Like Kent said, the cost-effectiveness using ANC's solution was dubious at best. I'd go with wiring a couple Cabletron transceivers together for the cheapest, most reliable solution. ---- Mark Foster CSE Systems Support Oregon Graduate Center Beaverton, OR fosterm@cse.ogc.edu
jshelton@deimos.ADS.COM (John L. Shelton) (02/12/89)
We make Null Ethernet cables here at ADS without any electronics.
Each ethernet cable has 4 PAIRS of wires:
Transmit
Receive
Collide
Power
We connect Transmit to Receive on the other cable,
Receive to Transmit
Collide remains disconnected
Power remains disconnected
It doesn't work for all devices, but for many.
Send me mail if you want details.
=John=