Like many Macintosh users, I've wanted to add a second Ethernet to an iBook (iMac, or Mac Mini) to use as a server (or as a replacement for a dead Ethernet built-in). Although USB to Ethernet adaptors are cheap and plentiful, Mac OS X drivers are not. After scouring the web and talking to other Mac developers, I finally found a workable combination. The purpose of this note is to document what works since I haven't seen it widely published anywhere else. I welcome your feedback to help keep this page up-to-date.
With the announcement of the MacBook Air, Apple began shipping their own USB-to-Ethernet adaptor and driver (AppleUSBEthernet). I understand Apple's USB-to-Ethernet adaptor should work on other Macs running Leopard 10.5.2 or later (Daniel Sumorok has verified this). It can also be used on systems running Mac OS X 10.3.9 or later by installing our latest USBAx8817x driver. Apple's driver is not designed to support 3rd party USB-to-Ethernet adaptors or prevoius OS versions. We have modified our own driver to take precedence over Apple's driver when it is installed, and recognize the Apple USB Ethernet Adaptor.
USBAx8817x 1.0.3b14 improved compatibility with Gigabit Ethernet adaptors. USBAx8817x 1.0.3b13 enabled Ethernet flow control. USBAx8817x 1.0.3b12 includes a 32/64-bit Universal Binary (for 10.5 or later). USBPegasusEthernet 1.0.9 updated to support SMC2208/ETH (ADM8513). USBAx8817x 1.0.3b11 tuned to improve performance with some adaptors. USBAx8817x 1.0.3b10 recognize Apple's USB-to-Ethernet Adaptor. USBAx8817x 1.0.3b9 increases the "probe score" returned for AX88772 devices to supercede AppleUSBEthernet. The Tiger version was renamed to "10.4_or_later" and installs a Universal Binary that has been tested on Leopard (Mac OS X 10.5). USBAx8817x 1.0.3b8 removes "expected NULL" warning messages that appear in the System.log under Leopard. USBAx8817x 1.0.3b6 and later support the new Ax88772-based DUB-E100, Airlink 101, and Belkin Gigabit USB Ethernet adaptors. USBPegasusEthernet 1.0.8 updates the project to build properly on Leopard and supports the NetGear FA101.
Next, plug-in your Ethernet adaptor with a live Ethernet cable attached. When you open the Network Preferences panel, it should inform you that a new port has been detected and ask if you want to enable it. Enable the new port and apply your network settings. On Leopard, the message indicating a new port has been detected may not appear, but you still need to Apply your network settings to enable the attached device for the first time.
To uninstall the driver, make sure any USB adaptors are disconnected, and then drag the corresponding driver in /System/Library/Extensions/ USBPegaususEthernet.kext or USBAx8817x.kext to the trash. You may need to authenticate that you have administrator privileges.
Using the Link Rate tool in IPNetMonitorX, I measured the link rate to another device on my LAN as 6 Mbps. The built-in Ethernet on my 12" PBG4 reported 44 Mpbs. When I measured the link rate to the next hop router through my cable modem, it reported 1 mbps. It didn't make any difference whether I used Ethernet built-in or the USB-To-Ethernet adaptor. Finally, I downloaded a 2.2 MB file to compare the throughput using the Monitor tool.
While the USB-To-Ethernet adaptor was slightly slower, at 80 Mbps there was little noticeable difference. Files moved quickly from one system to another via 100 Mbps fast Ethernet. Copying the same file using AirPort wireless took 50-90 seconds.
While other USB-To-Ethernet drivers are reported to be buggy, I haven't encountered any stability problems 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. 2b1af7f3a8