Dreaming of a single-cable docking station for my MacBook Pro, but not wanting to beta test the Belkin Thunderbolt dock, I decided to build my own using USB 3.0. This meant buying a sizable powered USB 3.0 hub (I chose the well-regarded Satechi “10 port” model) as well as a USB 3.0 Ethernet adapter. I already had a number of fantastic external drives, my Unicomp keyboard, and a (Bluetooth) “Tragic MacPad”.
Cable Matters USB 3.0 Gigabit Ethernet Adapter
Although Apple offers their own USB Ethernet adapter, it is USB 2.0 and 100 Mbps only. I wanted something faster than the 30 MBps those can manage. So I decided to take a look at the various USB 3.0 Gigabit Ethernet adapters on offer. It appears that most use the same chipset, made by a Taiwanese firm called ASIX, and thus would be similar apart from price.
My eye was eventually drawn to an inexpensive USB 3.0 Gigabit Ethernet adapter: Cable Matters SuperSpeed USB 3.0 to RJ45 Gigabit Ethernet Adapter in White. This adapter had fairly positive reviews from Mac users, and the price (US$20 with free Prime shipping) couldn’t be beat. So I took the plunge.
Despite the look of the packaging, this isn’t an Apple-grade device. It’s larger than Apple’s Thunderbolt Ethernet adapter and the white plastic has a cheap glossy (almost translucent) look that’s just a bit off. But that’s good enough for most users as long as it works.
Installation and Use
The first hurdle is drivers: This adapter’s chipset (ASIX’ AX88179) is not supported by Mac OS X. There’s a driver bundled with the adapter, but it’s on a CD-ROM – did Cable Matters miss the memo about Apple discontinuing optical drives?
Rather than dig out my portable SuperDrive, and because commenters on Amazon mentioned newer drivers, I fired up DuckDuckGo and searched for the latest driver from ASIX. Happily, it was easy to find the ASIX AX88179 driver page, which includes software for just about every OS you might run across. They even support Windows CE 6.0!
The driver is a DMG inside a zip file (?) with no auto-pop-up Finder window. It was an easy install, though the required reboot made me feel like I was back to using Windows.
After the reboot, I plugged in the adapter and connected my cable, but my Mac chose to use Wi-Fi instead of Gigabit Ethernet. A quick trip to System Preferences -> Network -> Set Service Order (in the gear drop-down) allowed me to prioritize the USB 3.0 adapter over my Wi-Fi network.
Once I changed the service order, everything appeared to be working smoothly. Wanting to test out the Ethernet adapter (and having video from Wireless Field Day 5 to post), I immediately started a 5 GB upload. A few hours later, I am pleased to report no trouble at all. I don’t really have the ability to stress test it at gigabit speed, but it seems stable and quick.
Warning: Illegal MAC Addresses!
Then I uncovered a serious annoyance: The MAC address.
I was checking out the connectivity in Network Utility when I noticed the MAC address used by this brand-new device. See above: It’s 00:00:00:00:02:d0. This might not matter to most people, but old-school geeks like me know that this is not a legal and kosher value. Cable Matters and ASIX seem to be playing fast and loose with their Ethernet setup!
Let me explain: Every Ethernet device has a MAC address, which is used to identify it on the network. This works below the IP addresses familiar on the Internet. The first three “octets” of an Ethernet MAC are the Organizationally Unique Identifier (OUI), and are set by the IEEE.
Since the MAC address is critical to sending Ethernet packets to the right place, every device on an Ethernet network must have a unique MAC address. Having an OUI doled out by the IEEE allows a vendor to manage their own MACs. If everything works as planned, every Ethernet device will have a globally-unique address. Cool, eh?
This is a fun way to identify devices at a glance: You can look up the first three octets using an IEEE tool and see who made any Ethernet device!
But take a look at 00:00:00 and tell me what you see! That’s right: This OUI belongs to Xerox, the originator of Ethernet. And 00:00:00:00:02:d0 is not a proper MAC address for a device made in 2013 by a company other than Xerox to use.
Duplicate MAC addresses can be seriously bad news. One saving grace is that, since it’s one of the earliest MAC addresses ever issued, the real 00:00:00:00:02:d0 probably looked a bit like this. So it’s unlikely to appear in the same network as my new Cable Matters device. In fact, it’s probably sitting in the back room at Weirdstuff or in a landfill.
ASIX punts responsibility for MAC addresses to the companies that use their chips. So when Cable Matters came calling with an OUI of “00:00:00”, I’m sure they didn’t bother to ask questions. They just set their machines to sequentially number their adapters starting at all-zeroes. As far as I can tell, Cable Matters doesn’t even have an OUI.
— Ed Horley (@ehorley) August 13, 2013
Is this a problem? I raised the question with some knowledgeable folks on Twitter, and they weren’t all that concerned at this point. A collision with an ancient Xerox adapter is inconceivable, but I remain concerned that other ASIX-supplied adapters could reuse the same 00:00:00 range, leading to issues where a large number of these cheap Ethernet adapters are in use. And other manufacturers are likely doing the same thing.
Then there’s the IPv6 issue: The next-generation Internet Protocol uses the Ethernet MAC address as an interface identifier, and this is used across the whole Internet. Although a collision there remains unlikely since there are other elements to the global IPv6 address, we will likely see lots of archaic Xerox addresses out there in the wild.
Should you buy a Cable Matters USB 3.0 Gigabit Ethernet adapter for your Mac or PC? On the hardware and software side, it seems fine. Once the drivers are installed, it functions adequately. But I am deeply concerned that a vendor that would cut corners on the MAC address and OUI would cut corners other places, leaving me skeptical about the company and its products. Therefore, I cannot recommend this device.