AirPort Extreme, Time Capsule: Like Two Base Stations in One

An update to Apple’s two higher-end Wi-Fi base stations enables a single gateway to serve any connected device at the highest possible speed. The trick? Apple stuck two radios in its latest AirPort Extreme Base Station and Time Capsule models, while keeping prices the same. The new models also offer an intriguing guest network feature. Alas, official support for Time Machine backups to an AirPort Extreme with an external hard drive remains lacking.

A firmware update for all 802.11n-capable base stations adds Back to My Mac support for remote file sharing with any AirPort Extreme Base Station or Time Capsule, and remote configuration via AirPort Utility to those models and the AirPort Express.

Dual-Band Networks — The choice facing anyone setting up a new Wi-Fi network is which of two spectrum bands to use, obscure as that sounds. In most countries, including the United States, the 2.4 GHz and 5 GHz bands are both available for use for Wi-Fi. The 2.4 GHz band is crowded: it’s used by microwave ovens, cordless phones, Bluetooth, and many other purposes; and there’s not much spectrum in the allotted range. The 802.11b and 802.11g (original AirPort and pre-2007 AirPort Extreme) standards can use only 2.4 GHz. The iPhone and iPod touch include 802.11g hardware.

The 5 GHz band is wide open, with several times the spectrum and far fewer conflicting uses. The 802.11n standard that Apple has offered since February 2007 can use either band, but 5 GHz is better for closer, denser networks because network throughput can be up to several times better than in 2.4 GHz. The Apple TV and nearly all Macs released since October 2006 include 802.11n support. (The Mac mini was finally updated last week to offer 802.11n.)

With last week’s update to the AirPort Extreme Base Station and Time Capsule, you no longer need to make a choice or connect two different base stations to get the best features of both bands: backwards compatibility with 2.4 GHz and throughput for 5 GHz. The revised models offer simultaneous dual-band networking at the same price as previous models: $179 for the Gigabit Ethernet AirPort Extreme, $299 for a Time Capsule with a 500 GB drive, and $499 for a 1 TB Time Capsule. The $99 AirPort Express base station remains unchanged, with support for either spectrum band, but only one at a time.

(I don’t currently recommend purchasing a Time Capsule for three reasons: First, I and others have experienced Time Machine disk image corruption repeatedly with no explanation, and no alternative but to delete older images. Second, Time Machine has proved unreliable for me in three separate installations. Third, the premium Apple charges for its server-grade – meaning, more reliable – drives is far too high compared to purchasing the same class of drives separately. I suggest referring to Joe Kissell’s “Take Control of Mac OS X Backups” for alternative network-based backup solutions.)

The advantage of using both spectrum bands is that slower, older devices can use the pokier 2.4 GHz band, while video streaming and file transfers among computers with 802.11n or an Apple TV can zoom along as much as three to five times faster in the 5 GHz band. The 5 GHz band’s signals don’t penetrate or carry as far as those in 2.4 GHz, however, making it more appropriate for closer networking.

In a briefing, Apple explained that you can give the 2.4 GHz and 5 GHz networks the same name, and Apple hardware that supports 802.11n can choose which network to join based on quality of the signal and the speed that’s available. This feature is unique to Apple gear; Windows and other platforms select somewhat randomly from available networks with the same name.

You can also name the two bands’ networks separately, and manually force 802.11n clients to join the 5 GHz network.

It’s worth noting that older base stations cannot be updated to support simultaneous dual-band networking because Apple added a second radio to these new models. All previous 802.11n models have a single radio that can be switched to use either 2.4 GHz or 5 GHz.

Guest Networks — Apple also added an intriguing guest access feature to both the AirPort Extreme and Time Capsule. With a guest network active, the base station broadcasts a second network name for visitors (a password is optional). Multiple network names are typically supported on corporate-oriented equipment; this is known as a virtual SSID (service set identifier), the technical name for a Wi-Fi’s broadcast network identity.

Those connected to the guest network have access only to the Internet; local hard drives and network traffic are locked out. A separate, advanced option lets you set whether or not guests can see each other’s network traffic, such as Bonjour discovery messages for shared volumes or iChat.

Note that you cannot configure the guest network to have different names for the 2.4 GHz and 5 GHz bands. The guest network must have the same name for both bands. Nor can you disable one of the bands for guest access without disabling the main network on that band as well.

As with the dual-band support, the guest network feature will not be made available to older base stations.

Remote Access with MobileMe — The update includes one last addition: a MobileMe tab that, when filled in with an active account, turns a base station into another accessible device from any Leopard system with Back to My Mac enabled. Back to My Mac creates a secure tunnel between any two devices using the same account credentials. This is the first time Apple has extended Back to My Mac beyond Leopard. (Normal provisos about Back to My Mac requiring a publicly reachable IP address on the gateway still apply.)

The Back to My Mac support works initially with two networked features: file sharing from internal or attached hard drives, and remote configuration via AirPort Utility.

A reader reported that his remote Time Capsule made its drive available to Time Machine, but that no backup was possible. Apple advised me that even if a user were to figure out a way to make this work, the backup time would be prohibitive because of how Time Machine creates a duplicate directory for each snapshot, involving a huge number of disk transactions.

The good news is that this feature, unlike the other additions to the new models, applies to any 802.11n base station Apple released, which is every model starting in 2007 via a firmware update released last week (see below). Because the AirPort Express doesn’t support plugging in hard drives, it won’t gain file-sharing support.

A system with Mac OS X 10.5 Leopard and a MobileMe account is required. The same account must be logged in at the base station and on the computer from which you’re trying to access the base station.

Software Updates and Troubles — Older 802.11n base stations – those that were released in 2007 or later – require the 7.4.1 firmware update that was released a few days after the new base stations were announced. Apple also pushed out AirPort Utility 5.4.1 and Leopard client software changes that enable Mac OS X to make the smartest band choice.

Launch AirPort Utility and it will either notify you of the new firmware, or you can select Check for Updates from the AirPort Utility menu. The update may also be downloaded directly from Apple’s Web site, and then installed via the Upload Firmware item in the Base Station menu in AirPort Utility. (The update includes bug and security fixes, too.)

You can get the AirPort Utility and client updates via Software Update or from Apple’s site: AirPort Utility for Mac OS X 10.4 or later (17.4 MB), AirPort Utility for Windows XP (SP2 or later) or Vista (10.9 MB), and AirPort Client Update 2009-001 for 10.5.6 or later (2 MB) are all available. There is no Tiger client update.

Joe Kissell had some trouble with the AirPort Utility 5.4.1 software and an older firmware release on his Time Capsule, which he figured out how to solve in “AirPort Utility 5.4.1 Update May Be Problematic,” 2009-03-05.

I was unable to get AirPort Utility to download the new firmware for my new simultaneous dual band base station at home, but was able to get MobileMe to work. Using remote access to my work machine, I used AirPort Utility at work to upgrade the firmware at home! Crazy, but it did the trick.