AUI crossover?

John> I am playing around with networking again, and realized I have John> a lot of AUI transcievers of different types, and only one AUI John> hub. Question is, can two AUI-male connecting converters be John> connected together with an appropriate cabelling, like you can John> do with RJ45/10bT, or must a person always use a hub/repeater John> box? John> here's my notes, looks doable any problems? 3 TX+ 5 RX+ 6 +12v John> return 10 TX- 12 RX- 13 +12v You missed the Collision wires, and therein lies the trouble. There are two issues. One is that an AUI based Ethernet was half duplex (just like 10Base2). If you just cross over rx/tx you have a full duplex setup. If the NIC is full duplex capable that MAY work, but depending on the NIC it may not be full duplex capable. The other issue is that 8u02.3 compliant NICs will expect the collision signal to assert briefly after each packet. That is the Collision Test (SQE test, see 802.3 section 8.2.2.2.4). DEC NICs, for example, generally implement this. I *think* this is a warning, so if the driver doesn't treat it as an error you'll probably be ok. You said you have lots of transceivers. So why do you want crossover? Just hook the AUIs to their coax and wire up a classic Ethernet that way. Or did you mean AUI based NICs? (For that matter, what's an "AUI Hub"? I know AUI repeaters, and I know AUI transceivers.) paul