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USB2NIC

USB to Network Interface Card Chipset Driver Support

Introduction

Like many Linux users, Ethernet ports for server projects are hard to come by. Additional Ethernet ports or a replacement for a dead Ethernet built-in becomes very difficult unless USB-To-Ethernet is made possible. Some servers have only 2 x PCI slots giving a maximum of 3 x NIC's if the OS or kernal supports the on-board NIC. Although USB to Ethernet adaptors are cheap and plentiful, adapters that are compatible with Linux are not.

Drivers and Supported Devices

There are two basic catagories of USB-To-Ethernet adaptors:

1. USB 1.1 devices that use a Pegasus driver.
2. USB 2.0 devices that use a AX8817x driver (or its successor, the AX88772 which appeared around Aug-2005).

While there are no doubt exceptions, most of the popular low cost adaptors fall into one of these categories.

Compatibility Notes

AX8817x devices are backward compatible with USB 1.1 host ports and are reasonably priced, so are probably the best option at this time. Pegasus based devices seem to be getting harder to find. Some USB 1.1 devices use the Realtek 8150 which is not supported by these drivers.

Some users report LinkSys has started selling a USB200M v2 which uses the Ax88772 chip in place of the AX8817x. The AX8817x driver has been recently enhanced to add support for this device in version 1.0.1 and later (12-Oct-2005).

Over the past year that manufacturers sometimes have upgraded devices to use a new chip set without changing the model number (LinkSys USB200M, DLink DUB-E100), or manufacture a batch of devices that report a different Product or Vendor ID code (DLink DUB-E100). If you have trouble getting one of these devices to work on the first try, don't despair there is more information on our feedback page.

Installation

Most Linux kernals have these drivers availabe for the above chipsets. It is simply a matter of installing them during setup or manually installing them at a later date

USB 1.1 Performance

The Pegasus chipset provides a USB 1.1 compatible implementation which could be a concern for some users. USB 1.1 runs at 1.5 Mbps (low speed) or 12 Mbps (full speed). For best performance, isolate any low speed devices on a separate bus. Mice and keyboards often run at low speed.

USB 2.0 Performance

The AX8817x chip set provides a USB 2.0 compatible implementation which runs at up to 480 Mbps (high speed), so it should be possible to keep up with 100 Mbps fast ethernet as long as there are no other slower devices on the same bus.

Stability

While some USB-To-Ethernet drivers are reported to be buggy, stability problems have not been encountered to date. The adaptor turns off when the computer goes to sleep and comes back on when the computer awakes. It does not support "Wake On LAN" at this time.

Conclusion

This USB-To-Ethernet Adaptor combination could be an attractive solution for setting up a firewall such as IPCop or Smoothwall where three or more network cards are needed. Since many low end motherboards have two PCI slots, this could prove to be a handy solution to get around these limitations

References

Sustainable Softworks - Retrieved on 21 September 2007

All text is available under the terms of the GNU Free Documentation License
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