Emulating network via pure USB cable - sanity check

[anaqer]

I'm looking into linking up two Windows PCs (98SE and XP Pro, to be precise) via USB - I need this primarily for file transfer (speed isn't really a priority, I could make do with at least half the theoretical limit of USB 1.1) and occasional gaming (so latency shouldn't be too big... let's aim for <50ms ping). A simple 10Base-T solution would of course surpass all these criteria - had I not run out of expansion slots in one of the machines (although the silkscreen for a LAN controller is right there on the motherboard PCB, just laughing at me... ).

Now I know that there are devices like NET-LinQ and such, but I'm not really in the mood for shelling out up to $50 for a piece of cable with a tiny blob in the middle. I figured this could be done without additional circuitry - say using a driver that encapsulates Ethernet frames into USB frames on both machines, kinda like a soft-NIC.

Has something like this ever been done (ie. can I just download it ) ? What kind of CPU overhead would we be looking at - specifically, could something like a P233MMX be able to handle this without excessive slowdown) ? How big of a project would this be - could someone who doesn't have experience with writing drivers, but is willing to learn, pull it off?

 

[Guden Oden]

Problem is, USB is a master-slave-like scheme, so there is no mechanism in standard USB to connect two 'masters', unless you buy one of those cables you don't want to buy. However, it seems to me the price you qote is vastly over-inflated, you should be able to find one for like $30 if you choose one that isn't a brand name item.

 

[anaqer]

Sorry about that fifty buck figure, your estimate is pretty much spot on - I just made a dumb mistake converting currencies. Still a bit much for my budget actually (the entire 98SE machine cost about that much) and I kinda like the idea of learning USB through a practical example.

Do we have any idea what sort of device is used as the slave in such a cable?
Is it a fully fledged network controller (even two maybe) - or can a cheap microcontroller do the job?

 

[BRiT]

Some ancient MSI boards had what they called PC2PC port. It required the use of their own drivers. It was basically a USB small connector to USB normal connector cable with special software. Here's a lil blurb on it:

PC2PC is MSI's gadget to make it extremely easy to connect to computer to each other without the need of a LAN card. Instead the USB ports will be used. How does this work? Connect the included cable to the PC2PC port on the bracket, and connect the other end to a USB ports on the second computer. That's it ... now you have the two computers networked to each other! This is a very cool feature that will make it very easy to quickly hook up to another computer to transfer some files or to play a deathmatch in Q3 for example!

But I dont know of any other means of doing so.

 

[anaqer]

Thanks for bringing up PC2PC, it led to a much more fruitful search than my previous "usb ethernet" "usb link" "usb network" etc. attempts which only resulted in links commercial solutions and provided little to no technical details.

This way I could learn that :

X-bit labs[/url]]The implementation of this innovation is based on an additional USB PC-to-PC File Transfer controller, Genesys Logic GL620USB-A, located on the left side of the board. It allows transferring the data between two USB ports at 8.6Mbit/sec.

and

Kwan's Research Laboratory[/url]]We have tried copy files between 850Pro2 and 770ED without a problem. We also did some benchmark test on the speed, we found that COPY/XCOPY under MS-DOS Prompt is faster that Drag-and-Drop under Windows GUI. CPU utilization is around 25%-50% during file copy.

and

http://www.linux-usb.org/usbnet[/url]]The Belkin device shown above has a microcontroller and two general purpose USB interface chips, but most other such devices take a lower cost approach using specialized chips.[...] Yes, you may occasionally see "A-to-A" cables for sale; don't waste your money buying them. Those cables are forbidden in USB, since the electrical connections don't make any sense at all. (If you try to use one, you might even short out your USB electronics and so need to buy a new system.) Basically, they're missing the extra electronics shown above, which is necessary to let a USB "master" (host) talk to another one, by making both talk through a USB "slave" (device).

Nice try, no cigar... looks like I'll really have to just make room for those NICs somehow.
(Hm, wonder how the V2 will like the restricted airflow... :?)

Anyway, thanks for the helpful pointers!

 

[PC-Engine]

Windows has this feature built-in but you can only use a serial or parallel cable. Don't know if the newer versions like XP allow USB cable connections between PCs.

BTW remember Laplink? I think it offers USB connections now.

 

[Guden Oden]

Nice try, no cigar... looks like I'll really have to just make room for those NICs somehow.

Told you so!

Windows has this feature built-in but you can only use a serial or parallel cable. Don't know if the newer versions like XP allow USB cable connections between PCs.

Like I already said, you can't connect computers together using USB, there has to be some device inbetween, and those cables that do have something inbetween need their own drivers as there is no standard USB network profile, like there is for keyboard/mouse/storage etc.

 

[PC-Engine]

Why not just get an external USB network adaptor?