On Mon, 28 May 2001, Gunther Schadow wrote:

> I found a blue coax cable in the trash at work. Looked like new.
> About 7 or 10 mm thick in a roll of 1 ft diameter. Probably about
> 5 ft long (all estimates.) It has an inward-threaded connector
> at each end. I can actually screw those on my CI bus connectors. 
> >From what I heard, I imagined a CI cable being a big pipe of 
> at least 1 inch diameter, was I wrong and I do have a CI cable?

Definitely sounds like CI cable.

> I know I would need a star coupler to do anything useful with 
> this, right?

Yes.

> However, I'm not eager to run an HCS as I don't really want to 
> build a cluster around common storage. Instead, I was wondering 
> about other uses of the CI bus. I heard it is pretty impressive in
> terms of throughput, so would be a waste if it ended up unused. 

70 Mbit/s if I remember correctly. And it's full duplex and dual channels.
So I guess you might be able to get 140 Mbit/s full duplex.

> And since a 100-TP Ethernet card does not exit for VAXen, I wonder 
> whether one could use a CI bus as a data link layer for IP? Not 
> having any documentation about it I can't really say how, and not 
> even having a working machine (yet) it certainly is all theoretical. 
> But I wonder that this super CI link technology is not put to more 
> interesting use than just sharing mass storage (and if built with 
> RA80's one can hardly even speak of "mass" anymore :-).
> 
> So, I could imagine using CI as a link layer for IP just like 
> Ethernet. Anyone ever tried that or knows otherwise that it 
> cannot work? 

Ultrix allows you to do this. The MTU Ultrix uses for the CI is 8192 bytes
IIRC.

> My CI interface has 4 connectors "A" and "B" for each 
> input "->0" and output "0->". Will one connection to a star
> coupler use all four of those or only two? How absolutely
> certain is it that one cannot make a direct link between two
> machines without a star coupler? Like you can make a direct
> link between two 10/100-TP ethernet ports with a crossover
> cable? One would simply cross the input connector of one machine 
> over to the output connector of another machine and vice versa.

I think you need the SC, but I wouldn't say I know for sure...

	Johnny

Johnny Billquist                  || "I'm on a bus
                                  ||  on a psychedelic trip
email: bqt@update.uu.se           ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol