AUI is not symmetrical, and passive crossovers can't work.
There are active devices, the most famous one is called DELNI, which can be used to perform the function that you ask.
I also used to have two and four port transceivers that, when properly terminated, would perform that function.
My first work with thick ethernet used two and four port transceivers. One day I was having problems with a two port that had been working. After working on it for a while, I figured out that it failed when a transceiver cable was connected to the unused port without a host. I then built my own AUI terminators, and complained to the company that made them. There answer was to send us some AUI terminators. The four port version didn't have that problem, though.
Hello from the Eighth Doctor For my problem to be solved, (See the earlier threads concerning a strange networking problem.) I placed an e-mail to a company who made a gizmo which translates between COAX, and UTP. They claim the gizmo is now discontinued, but they have been saying that for about a year.
Anyway while searching for solutions, and found them, I came across an e-mail embedded in a webpage regarding a crossover AUI cable described inside Tomi Enghdahl's terrific website.
Basically it's two connectors wired together, instead of straight through, he's got the wires crossing over. Transmit on one to the receiver on the other, that sort of thing.
Hello from the Eighth Doctor I agree. That blurb was the first one to surface from a Google search. I just finished using one of their search engines for the DELNI. I would have better luck wiring something of a sort.
Does anyone on the NG have just such an item roosting in their equipment room, that they obviously do not need, and would be willing to part with, I'll pay shipping charges? And if your located in the tri-state area, (NY, NJ, CT), I'll take anything medium sized that's not needed as well, physically. Please e-mail for physical address.
But according this Usenet news article that is archived at
a suitable passive crossover could work on some cases:
Newsgroups: comp.dcom.lans.ethernet From: firstname.lastname@example.org (Matthew Deter) Subject: Re: AUI to AUI cheaply, how? Organizati : I, too have a similar need, and turned to this newsgroup for the express : purpose of asking about pin numbers! Tell us about your experience of 10 : years ago. I've got plenty of experience in making cables and the right : tools, but just need the pin numbers if in fact it is doable.
The following is a reply I received when I asked this exact same AUI AUI "null modem" question a while back. (I forget which group I asked on...)
I **DID NOT** try out this wiring diagram, as the need evaporated before I had a chance to try it out. (I found some BNC transceivers laying around. :-)
**Try this at your own risk.**
From snipped-for-privacy@vnet.IBM.COM Wed Oct 6 02:43:18 1993 Date: Wed, 6 Oct 93 10:42:20 BST From: "Andrew J V Yeomans" Subject: AUI AUI cabling question
I've done the following, and got it to work. No promises, try at your own risk!
Shield 1 1 Shield Collision Detect A 2 2 Collision Detect A Transmit Data A 3 ----\\ /---- 3 Transmit Data A (Receive Data Shield) 4 X 4 (Receive Data Shield) Receive Data A 5 ----/ \\---- 5 Receive Data A Vc 6 --- --- 6 Vc (Control Out A) 7 | | 7 (Control Out A) (Control Out Shield) 8 | | 8 (Control Out Shield) Collision Detect B 9 --- --- 9 Collision Detect B Transmit Data B 10 ----\\ /---- 10 Transmit Data B (Transmit Data Shield) 11 X 11 (Transmit Data Shield) Receive Data B 12 ----/ \\---- 12 Receive Data B V+ 13 13 V+ (V Shield) 14 14 (V Shield) (Control Out B) 15 15 (Control Out B)
-- Andrew Yeomans 081-818 4288 NOSS/VNET: BASVM1(YEOMANA) Internet: email@example.com IEA: GBIBML89 at IBMMAIL IBM Ltd, 1 New Square, Bedfont Lakes, Feltham, Middx, TW14 8HB
-- $$ Matthew Deter $$$$ firstname.lastname@example.org $$ $$$$ "The fortune of my spirit is not to be blown into coins of brass $$ and flung to the winds as alms for the poor of the spirit." $$$$ $$ -- from the novel _Anthem_ by Ayn Rand