andrew carter

Last week, I got the new Apple AirPort Extreme base station. I have a MacBook Pro that is able to be enabled for 802.11n so increasing the wireless network speed was desirable. Plus, I’ve been interested in NAS solutions. I had a Linksys NSLU2 device. It was close to what I wanted but in the end, just not reliable enough. With that in mind, here are some impressions of the device.

Hardware

I have a more complicated than normal home network. I own 6 Mac’s, a Dell server, and three game consoles. All are on the network. Three of the Mac’s use wireless (two laptops and an iMac). The rest are wired. My house is wired with CAT5e to a home run location in a closet on the first floor. All the wired net taps are through Netgear gigabit switches. My broadband is Qwest DSL through a Cisco 678 at 1.5M/800k. The DSL modem feeds a Linksys WRT54GL running OpenWRT. The Linksys runs an 802.11g access point with an extra D-Link 802.11g access point upstairs. Get all that?

Router

When I had DSL installed in the house, Qwest setup one particular jack to work with DSL and the rest of the house is filtered. Consequently, there is only one location that the DSL modem will work. It’s in a good place in a patch panel in a first floor closet. The WRT54GL is in the same panel along with the Netgear gigabit switches. However, adding the AirPort Extreme provided a new dilema. If I put it in the panel, I can’t use the AirDisk feature. So I decided to leave the WRT54GL as the primary DHCP router and as a 802.11g access point.

I did look over the feature set of the AirPort Extreme and it looks very good. I would consider my networking knowledge above average so I don’t mind the complexity (or power) of running OpenWRT. It’s not for the faint of heart. OpenWRT can do nearly all the same features as the Apple device but without the ease of use. I especially like the guest features and the ability to lock down specific network devices at times of the day. Those are very slick features. I wouldn’t hesitate to use the Apple router as the primary backbone of a network. It even includes some more sophisticated features like Radius authentication. I’m sure these will be appearing in lots of university networks over time.

802.11n

I debated on the right approach for my wireless network. I have never had good luck using a single device for the entire house. The house is large but I flat out can’t get a decent signal from one floor to another. It is fine when there is an access point on each floor but neither provides much coverage to the other floor.

802.11n is supposed to have better range. I found this to be true sometimes. I put the AirPort Extreme on the first floor in my office. The signal downstairs is rock solid and the speed is impressive. But once I went upstairs, it tanked. Nothing. So much for any hopes of going to a single access point. So I get nice fast 802.11n downstairs and fall back to 802.11g for upstairs.

I also debated on what is the right way to configure the network. Given that I wasn’t removing the WRT54GL, I figured it made no sense to limit the 802.11n network to 2.4GHz. In the end, I decide to create two distinct networks that are both bridged to my lan. One network runs with two 802.11g 2.4GHz access points and the other is 802.11n 5GHz. It does mean that I have to pick which one to use. I want to look at how well roaming works when the network is composed of two different frequencies. Ideally, it would be cool to walk out of the 802.11n zone into the 802.11g and have it be transparent. But I’m skeptical that will work reliably.

AirDisk

Now the main event, the NAS feature Apple calls AirDisk. Again, I would have to say that I found this to be mixed. First off, the configuration and implementation are flawless. You do need to prepare a USB 2.0 drive on another computer then attach it to the AirPort Extreme. It will automatically share the drive with no password, a single password, or a set of users. Under the covers, the AirPort Extreme will use the standard Users/Shared layout used on OS X. It is also easy to take a drive back to an OSX machine and use it directly. I used this method to copy my 150GB+ media collection over to a Maxtor drive for the AirPort Extreme.

There are some new extensions to Bonjour that I don’t totally understand yet but basically network disk shares show up very similar to other Bonjour resources. There is also a new daemon utility that can watch for drives to be shared and automatically mount and unmount them as appropriate. This works very well especially for laptop users. You hook up your laptop and the shares all popup.

There is one very bad part to all this - performance. The transfer speeds are underwhelming at best. Here are some tests I ran to compare transfer times on a 40MB file:

Network	Source	Destination	Upload	Download
Gigabit	MBP	AirDisk	8.037 ( 4.977 MB/s)	6.254 ( 6.396 MB/s)
802.11n 5G	MBP	AirDisk	15.035 ( 2.660 MB/s)	10.516 ( 3.804 MB/s)
802.11g 2.4G	MBP	AirDisk	35.840 ( 1.116 MB/s)	17.753 ( 2.253 MB/s)
Gigabit	MBP	PowerMac G5	0.616 (64.935 MB/s)	1.294 (30.912 MB/s)
802.11n 5G	MBP	PowerMac G5	3.962 (10.096 MB/s)	0.566 (70.671 MB/s)
802.11n 5G	MBP	PowerMac G5 FW	3.901 (10.254 MB/s)	0.527 (75.901 MB/s)

There has been lots of speculation and conjecture on the internet about AirDisk performance. I think the core of the problem is that USB is not a good interface for hard disks. Firewire 400 has a higher sustain rate and Firewire 800 blows them both away.

Even with the performance limitations, the AirDisk does work well. I have been running my iTunes collection directly off the AirDisk and have had just one time where I lost the connection and locked up iTunes. Given the scenarios that people will likely use AirDisk, I think sustained media streaming and backups are the two big ones. So far, it seems like it may be able to handle it. I have not stressed streaming video files though so that could be something that isn’t possible. I’m getting an AppleTV when it releases and expect that’s when I will really find out.

Conclusions

This is a good device but not great. The sum is better than the individual parts. The management interface and ease of use are second to none. Performance has some room for improvement. I’m hopeful that some firmware changes could see some improvements.

As a new device category, this could be huge. Time Machine in Leopard will be a great candidate for a network file share. I’d prefer to use a low power NAS solutions instead of big, noisy computers.