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I have a Ethernet cord with a forked end, one connector is USB, the other normal CAT5 (and the other normal CAT5). I'm trying to get a Windows 7 laptop that has a broken NIC connected to the internet via the USB (has to be a wired connection) but I have no idea how I might do this. All of my research so far has simply led to results on USB over Ethernet rather than Network over USB.

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Can you post a picture of the cable? Just because it has a RJ45, doesn't mean that it is Ethernet, Are you sure it isn't a router console cable? – Zoredache Oct 20 '11 at 18:20
It sounds like USB over Ethernet is exactly what you want. Network over USB exists, but it can only be used to connect two devices, each of which connecting by USB. (It basically creates a fake network including only those two machines.) – David Schwartz Oct 20 '11 at 19:51
@Zoredache tbh, not really, it came with a previous modem... but I am sure that it's ethernet, but not that it'll do more (e.g. usb ethernet adapter) – xenoterracide Oct 20 '11 at 21:05
up vote 5 down vote accepted

The "Ethernet" + USB cable that you have is not for generic use, but rather for a specific device that can accept either 10/100 Base-T or USB signals through its RJ45 port. Since 10/100 Base-T uses only two twisted pairs (or 4 conductors) and USB uses 4 conductors, an RJ45 connector with 8 contacts could be used as a device's port for both interfaces.

However this is a nonstandard combination of interface signals for a connector, and I've only seen this done on a DSL modem. And for proper use in that case, only one side of the "fork" was to be used at a time. This splitter cable that you mention is essentially useless w/o its intended device.

As already mentioned, a USB-Ethernet adapter (with active circuitry) will accomplish what you want. It will be another NIC to your computer. (I've tested and used several brands of USB-Ethernet adapters in Win XP and 7 and Linux.)

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+! This sounds right. I have seen a couple of these types of cables come with a DSL modem. These will not do anything useful for what it sounds like he wants. – Zoredache Oct 20 '11 at 21:15

TL;DR The short answer is that you'll probably need to purchase a USB Ethernet adapter, which has a USB connector at one end that you plug into your computer, which will see the device as a new network card, and then connect your network cord to the other end of the adapter.

I've never seen or heard of a cord like this. Is there any sort of adapter or circuitry at the fork in the cable? Is there a particular name to this cable? Are both ends forked or just one?

The problem is that USB and Ethernet are two completely unique sets of connectors and signals. Connecting the wires of an Ethernet cable to a USB connector will result in a useless connector.

What it sounds like is that this cord allows you to connect to a device using PoE, or Power over Ethernet, without having a PoE host. PoE is used for office IP phones and various other relatively low power devices that generally only have a network connection and not a power connection. By sending some power over the Ethernet cable, you can power the entire device.

If, however, the host or switch you're connecting to does not provide power, you're probably not going to get the device to work. So, and this is my guess only, they put this USB connector which should provide up to 12 volts connected to the Ethernet wires that would handle the power, allowing a non PoE host to run a PoE device.

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I've never seen a cable like that. Where did you get it? Perhaps it steps up USB voltage to provide Power-over-Ethernet.

USB/Ethernet adapters do exist, but they are dongles with an obvious brick containing the necessary electronic converters. There is no way to simply splice the two cable types together.

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Since the NIC is broken, you need a new NIC. You can get a NIC that connects by USB if you want.

I'm not sure what you mean by "network over USB". What doesn't a USB NIC do that you need?

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