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Evolution of the ABS:

Or, should I upgrade?

Apple revolutionized high-speed wireless networking in 1999 with the introduction of the Airport system. While such networks were developed long before Apple partnered with Lucent to develop the first generation ABS (a.k.a. "Graphite"), it was Apple that popularized the technology by introducing a fully functional base station at a price point 3x below that of the closest rival.

Not only did the ABS allow its users to untether themselves from wires, it also allowed to do it with the ease that Apple users expect. Naturally, laptop users were the first to be converted but as Apple revised its hardware offerings to optionally include Airport cards, even desktop users started using Airport. After all, why run cables throughout an office/house unless you really need to?

No technology is without its flaws, which is why Apple apparently beta-tested the gear for Lucent in return for a one-year exclusive contract. While the initial "Graphite" ABS suffered from design flaws and subsequent widespread power supply failures, the technology overall was a resounding success. Once people got a taste of it, they refused to go back.

This short article is meant to show the differences as the ABS design evolved through the generations. It also attempts to answer the questions that I received from some readers regarding whether they should upgrade to Airport "Extreme" . Let me start with a comparison table that looks at the relevant differences between models:

Generation1st: "Graphite"2nd: "Snow" 3rd: "Extreme"3rd: "Express"4th: "Extreme-n"
Underlying Processor AMD Elan SC400 (embedded 486) Motorola PowerPC 860 AMD Au1500 series Broadcom BCM4712Marvell 88F5181
Maximum Wireless Speed 11 Mbit/s 11 MBit/s 54 Mbit/s 54 Mbit/s300 Mbit/s
802.11 Protocols supported b b b,g b,ga,b,g,n
Installed Transmitter Fully-functional Lucent WaveLan "Silver" PC-card Airport (proprietary PC-card w/o antenna) Airport Extreme (proprietary Mini-PCI card w/o antenna) Built into motherboard (!)Atheros daughter-board
External Antenna Possible? Via Retrofit Retrofit possible, though benefit in doubt Part of $50 modem option.
Retrofit possible, though benefit in doubt.
Possible, but VERY difficultPossible, but worth the trouble?
Dialup Modem? Yes Yes Optional (see above) NoNo
ISDN Modem?via Hermstedt upgradeNoNoNoNo
Antenna Plug Type MC-Card MC-Card External: MCX
Internal: MC-Card
Hirose mini coax jack (?)3 Hirose mini coax jacks
Max. WEP Key Length 40 bits (104 possible via Retrofit) 104 bits 104 bits 104 bits104 bits
WPA available?NoNoYesYesYes
VPN Compatible?Not if NAT is EnabledYesYesYesYes
LAN/WAN Ethernet Ports (Mbit/s) 1 (LAN or WAN) @ 10 1 LAN @ 10/100
1 WAN @ 10
1 LAN @ 10/100
1 WAN @ 10/100
1 (LAN or WAN) @ 10/1003 LAN (10/100)
1 WAN (10/100)
Wiring Autosense? No Yes Yes Yes Yes
Built-in USB Print Server? No No Yes Yes Yes
Built-in hard-drive Server? No No No No Yes
Can be called by computer? No Yes (after upgrade w/Airport 2.04+) Yes (Modem version) No No
Audio Connection via AirTunes? No No No Yes No
Bridge Mode? Via Clumsy Retrofit No Yes Yes Yes
Universal Power Supply? No, Retrofit possible No, Retrofit possible Yes Yes Yes
Music ServerNoNoNoYesNo
Full Specifications Here Here Here Here Here
Evolution of the Apple Airport Base Stations
Processor
Most of us couldn't care less what processor powers our computers... However, every generation of base stations offers a new set of processors. There must be a reason that Apple bothered to switch processor families, as it basically forces Apple to maintain multiple sets of firmware (one binary for each processor).

The first generation "Graphite" base stations were powered by rather generic AMD Elan SC400 processors. These are embeddable 486 processors very similar to the ones that powered Windows machines not too long ago. The main benefit is the easy programmability. The main downside is that you are using a general-application chip for a very specific purpose - which is less than efficient.

This explains in part why enabling the DHCP server, NAT, or (much worse!) WEP causes significant degradation of "Graphite" base station performance. Later base stations powered by processors more suitable for them (either the Motorola PowerPC 860, the Extreme's AMD Au1500, or the Marvell 88F5181) seem to suffer less as features are enabled.
Speed:
On the face of it, the new Airport "Extreme-n" offers 5x higher bandwidth than the preceding systems. However, this is the maximum speed that the wireless portion of the ABS can sustain, assuming that all computers attached to the wireless network have near perfect reception and are running the same "n" protocoll. Should any computer attached to the wireless network run a slower protocol (a,b,g) then the base station will slow down to accomodate that computer.

Furthermore, few if any users will saturate that bandwidth considering all the other bottle-necks between them and the data on the internet. Most cable-modems and DSL lines are limited to speeds below 10Mbits/second. Thus, even assuming that the data you want is easily accessible, the internet can only feed the ABS at a 10Mbit/s rate. And this is the best case scenario. Usually, there is some link in your Internet chain that is far slower than that... and the connection is only as fast as the slowest link.

For dialup users, the potential wireless speeds are completely irrelevant unless they transfer a lot of data within their home (i.e. on their own network, not to and from the internet via the dialup modem). Indeed, the only real beneficiaries of the speeds that the 802.11n protocols offer are those that share a lot of data wirelessly in close proximity. Consider though that actual Airport throughput typically trails the performance of fixed wire networks of the same speed rating by a factor of up to 3x, even if all other factors are the same (due to overhead, re-transmissions, collisions, etc.)

Thus, if you're going to do video-editing over a LAN, go with gigabit copper instead. For casual home surfing on the internet, the transmission speed of every base station is adequate.
Protocols
There are four major protocols in home use today.
ProtocolDescription
802.11a

Transmits within the 5.8GHz band, which is not as crowded as the 2.4GHz band used by 802.11b&g devices. Therefore, it is likely that there is less interference to contend with. On the other hand, very few people use 802.11a due to the higher product costs, lower typical range, it's incompatibility with 802.11b devices (though a/b/g devices have become available), the smaller 802.11a adoption rate, and because 802.11g offers the same maximum speed (54Mbit/s).

Perhaps this is why Wireless ISPs (WISPs) prefer to use 802.11a connections for long-distance Point-to-Point connections. Outside, the attenuation of 802.11a signals isn't that bad, there is less interference, and high-gain antennas enable the WISP to connect reliably over vast distances, no matter what the weather.

802.11b

This was the first standard to become widely popular, in part due to Apples pioneering efforts with the Lucent-based "Graphite" ABS. It uses the same frequency spectrum as microwave ovens, portable phones, and other gadgets (2.4GHz).

Thus, interference can be an issue. However, this remains the most widely adopted and most popular wireless technology for a reason: It works, and for most people it's fast enough (11Mbit/s). "Snow" and "Graphite" base stations are limited to 802.11b mode only

802.11g

Following in the footsteps of the 802.11b technology, 802.11g uses the same frequency spectrum and thus has the same interference issues. However, it also offers speeds up to 54Mbit/s and backward compatibility with the widely used 802.11b standard. "Extreme" and "Express" ABS' can operate in b-only, g-only, or b&g mode.

Note: 54MBit/s speeds are only available in very close proximity to the base stations. Further away from the base station, the speeds of 802.11b and 802.11g networks are largely the same and depend primarily on the strength of the signal and any intereference you may be experiencing.

802.11n

A new protocol, which has not been finalized just yet by the IEEE, it builds on the foundations of the preceeding protocols and adds a few twists. With a theoretical throughput of up to 300 Mbit/s, it's fast, and with support for multiple antennas, it can offer greater range than a/b/g-only systems. Furthermore, Apple's implementation runs on both 2.4 and 5.8GHz, giving you a choice of choosing the least-crowded spectrum.

Choice of Transmitter:
The transmitter has little bearing on most users - we just want them to work. However, the transmitter inside your base station can have a important impact. Here are the first four that Apple has used. All of them operate within the unlicensed 2.4GHz spectrum and offer between 11-14 channels depending the jurisdiction you live in.

CardDescription
WaveLAN Silver Card
1st Generation WaveLAN Silver Card
The "Graphite" ABS has a fully-functional Lucent "Turbo Silver" WaveLAN card in it. Since these WaveLAN cards sport an internal antenna, you can take them out of the ABS and use them in the PC-Card slot of your laptop, if you want to. This is what many people did when their "Graphite" ABS' power supplies failed and Apple told them that they now had a $300 paperweight.

The WaveLAN card also came in a "Turbo Gold" edition. The only difference between the Gold and Silver edition is that the Gold edition can access 128bit WEP networks, while the Silver edition was reduced via firmware-crippling to 64bit WEP only. While there is a hack to make the Silver edition 128bit WEP-capable, the only way I know to actually bring 128bit WEP to a "Graphite" base station is by retrofitting a Gold card and using non-Apple software to configure it.
Airport PC Card
2nd Generation "Airport" Card
Starting with the second generation ABS ("Snow"), Apple switched its Airport hardware fully to its PC-Card-like but proprietary "Airport" cards. Note the shorter length due to the absence of an internal antenna. Instead of relying on an internal antenna, Apple hid external antennas in its computers and base stations.

Initially, regular "Airport" cards offered up to 128bit WEP security. If your computer is running OSX 10.3 and Airport 3.3 or higher, then you can even upgrade to WPA security. However, there is no current means of running WPA with "Snow" base stations. Lastly, there is no Apple-based upgrade path to "Extreme" performance (i.e. 802.11g) for folks who have machines with these cards.
Airport Extreme mini-PCI Card
3rd Generation "Airport Extreme" Card
The ABS "Extreme" uses a Broadcom-based Mini-PCI card as a transmitter. These 802.11b&g capable Mini-PCI cards are found throughout the current Apple product line. They are even smaller than the second generation "Airport" cards and cannot be used in the second generation "Airport" slots.
Airport Express Motherboard
4th Generation "Airport Express" Chipset
In the Airport Express, the 802.11b&g transmitter is integrated right into the motherboard. It's incredibly compact and usually hidden behind the antenna.
Airport Extreme -n Card
4th Generation "Airport Extreme-n" Card
The ABS "Extreme-n" uses a Atheros-based SO-DIMM board. Note: "n-mode" is only supported on relatively recent Mac hardware, including Core Duo 2 laptops and Xeon-based systems. Thus, verify that your computer can take advantage of the higher speeds that the n-mode offers before your buy a base station that offers n-mode.
Antenna choices:
The original ABS came with a fully functional Antenna on the Lucent WaveLAN card. Retrofitting an antenna is possible with a bit of sweat via the MC-Card connector. The second generation ABS initially posed some problems when it came to retrofitting an external antenna due to the way the inner case was designed. However, with the right antenna cables, this became even easier than with the Graphite ABS. The Snow model also uses the MC-Card Connector.

Please note that several "Snow" and "Extreme" users have written to me stating that the efficacy of MC-Card based antenna solutions did NOT meet their expectations. That is, adding an antenna to the internal MC-Card connector in these base stations did not result in adding 15%+ extra range. As antennas are not cheap, it may make more sense to use an Airport Express with WDS to extend the range of your home network. Long-distance connections still work best with good antennas, however.

The older Airport "Extreme" offered a external antenna connector in conjunction with a dialup modem as a $50 option. The external plug has been confirmed by three sources to be a regular MCX kind. Inside the ABS Extreme, the plug is a MC-Card type with the same fit issues as with the "Snow" base station. In other words, Apple is trying to make the retrofit of external antennas as difficult as possible.

The "Airport Extreme-n" promises up to 2x the range of the previous ABS' by virtue of the multiple antennas that the n-protocol supports. Time will tell if those claims are borne out in real life.
Security:
No wirless network can ever approach the security of a wired network because it is so much harder to prevent wireless packets of information falling into the wrong hands. For example, some hackers in Los Angeles recently demonstrated how Bluetooth telephones could be detected at ½ mile range, even though Bluetooth operates at much lower power levels than Wifi.

Since preventing others from "sniffing" your data transmissions is practically impossible, the next-best thing is to make said data worthless. The best way to do this is via robust encryption. While the encryption options on a "Graphite" base station were laughable at best, the WPA-encryption on later (Extreme and Express) base stations actually feature fairly robust encryption options that will keep most hackers out.

For a comprehensive look at what options exist and for setting recommendations by base station, look no further than my Encryption page. As more and more people adopt wireless networks, wireless security becomes ever-more important. Thus, wireless security is a good reason to upgrade from a "Graphite" base station to a later model.

A passive means of preventing people from connecting to your network is the ability of "Extreme" and "Express" base stations to adjust their transmitter output levels. That is, you can reduce the power of your base station via the Airport Admin Utility. This may be a useful feature for those who live in dense urban environments and only need to cover a small apartment. Similar results can be obtained via attenuators on Snow and Graphite models, or by the adoption of a higher multi-cast rate.

Please remember: When it comes to security measures, remember to set up your network in stages: first get it going with no encryption, and gradually increase security so that you're aware of which step/measure causes any bugs.
Virtual Private Network (VPN) Compatibility
However, if security is really important to you, I suggest using readily available tools like PGP, SSH, etc. to create a Virtual Private Network (VPN) and hence prevent others from snooping on important data that is in transit. Remember, the wireless portion of your network isn't the only vulnerable spot. For example, most internet related protocols like FTP, POP, and Telnet do not encrypt passwords or their data streams by default. Thus, any compromised machine along the way to and from the sites and services you use on the internet can be used to collect your login names, passwords, and data.

Unfortunately, Apple made the use of VPNs impossible on "Graphite" base stations whenever Network Address Translation (NAT) is turned on. NAT allows the base station to act as a router and share a connection to the internet among several users simultaneously. Apple seems to have fixed this flaw in later ABS'. If you own a Graphite ABS and need NAT and VPN connections, I'd upgrade.
Ports found on Airport Base Stations
First, some definitions and symbols you may encounter when you look at your ABS:
Local Area Network (LAN) Port
LAN port on ABS
This is the only high-speed port found on "Graphite" base stations where it acts as a WAN or LAN port. A "Graphite" ABS could either share a ethernet-based internet connection wirelessly, or allow other ethernet-connected computers to share a dialup connection. Lucent, Apple's collaborator on the "Graphite" base station, evidently saw no need for a dedicated set of WAN and LAN ports and hence did not include them. Apple had a chance to make up this mistake starting with the "Snow" ABS.

On "Snow" and "Extreme" base stations, you can use the LAN port to connect home machines to the ABS. This is particularly interesting to folks who are using their ABS as a router. The "Snow" and "Extreme" LAN ports run at 10/100 Mbit/s while the "Graphite" LAN port is limited to 10Mbit/s. Thus, don't attempt to hook up a "Graphite" ABS to a 100BT hub - it won't work!
Wide Area Network (WAN) Port
WAN port on ABS
With the completely redesigned "Snow" ABS, Apple added a 10Mbit/s WAN port. Thus, "Snow" users could use their ABS as a router to share a high-speed internet connection with their wired and wireless network. Some criticism was levied on Apple for the slow speed of the WAN port in Snow base stations - it made them unsuitable for heavy-duty commercial use.

With the "Extreme" base stations Apple fixed this oversight. They offer a faster WAN port (10/100 Mbit/s) that runs at the same speed as the LAN port. In addition to the potentially faster 802.11g protocol, this finally allows folks to move a lot of data quickly and without undue bottle-necks.

Note: Only connect the WAN port on "Snow" or "Extreme" to a hub, switch, cable/DSL modem, etc. to provide the ABS with a high-speed connection. Otherwise, it might go to sleep on you.
Auto-sensingThe ability of the chips inside the device to determine if a "cross-over" ethernet cable is needed, and if so, to automatically switch the inputs to create one. This eliminates the need to keep dedicated "cross-over" cables on hand at all times.

This feature is particularly useful when you need to connect a ABS directly to a computer instead of going through a hub or switch first. Traditionally, such a situation required a dedicated "cross-over" ethernet cable instead of a "normal" one. Naturally, this could lead to all sorts of confusion if you pull the wrong ethernet cable for the job at hand. Only a cable tester would identify the problem conclusively.

In other words, Auto-sensing takes some of the complexity out of building ethernet networks. With the right documentation and tools, it isn't necessary, but it makes life easier. Older computers and "Graphite" base stations do not have Auto-sensing ethernet chip-sets, making them somewhat more finicky to set up.

Even better, "Extreme" and "Express" base stations can be forced to run at predetermined speeds (10 or 100MBit/s in half or full duplex) on their LAN and WAN ports, even though they normally auto-negotiate the highest speed possible. Thus, professional grade features are available to administrators while home users can enjoy a simple-to-use system. Neat.
Telephone Port
Telephone port on ABS
Found on "Graphite", "Snow" and optionally on "Extreme" base stations, you can use the telephone port to connect via dialup to an ISP. If you take a closer look the base station, you'll notice that this port (a.k.a. a RJ-11 plug) is narrower than the high-speed ports (a.k.a. a RJ-45 plug).

With a maximum throughput of just 53Kbit/s, the modem is by far the slowest port found on a base station (if so equipped). The actual modem consists of a daughterboard that is mounted onto the motherboard in each base station. "Extreme" base stations w/o the modem option simply miss the daughterboard and do not feature a cutout for the plug in the external plastic enclosure.
USB Port
USB port on ABS

This port is only found on "Extreme" and "Express" base stations and allows you to use a compatible printer with your ABS. This is a great way to share a compatible USB printer between machines without the need to keep switching USB cables or keeping one machine running with USB-printsharing turned on. However, only folks with OS X 10.2.3 or higher can easily use such a printer.

On the "Extreme-n" base station you can also attach a hard drive with a USB interface to create a network-attached storage device. With a USB hub, you can even run a printer and a hard drive at the same time



If you're pushing a lot of data locally or have the base station in a busy office environment, then upgrading to a "Extreme" base station is worth it. Other approaches include upgrading the network piecemeal as equipment ages. Here it is best if you use of 10/100 ethernet switches instead of hubs (many routers and the "Extreme-n" offer built-in switches). With a switch, any slower network segments do not affect the network as much (they are compartmentalized). Furthermore, only the segments that need to talk to each other actually communicate with each other instead of broadcasting everywhere.

So, if you wanted to add some "wired" computers to a Graphite base station but couldn't because LAN/WAN port was in use already for the ethernet-based connection to the internet, you may consider going to the Airport "Extreme". However, there are many $50 routers available which allow you to put the old ABS behind a firewall and still share the ethernet connection. Thus, I would not upgrade to Airport "Extreme" on this feature alone.
Share your USB Printer
Theoretically, one of the neatest features of the "Extreme" and "Express" ABS' is the addition of a wireless print server that allows you to connect a USB printer to the ABS and set it up as a network printer. While some folks are still having trouble with their specific printer (check before you buy!) this feature seems to be working for many printer models. Note though that Apple states this feature only works for computers with OS 10.2.3 or later.
Share your hard drive
The "Extreme-n" base station ups the ante by supporting hard drives as well. This opens up all sorts of possibilities, from a shared iTunes storage library to a power-efficient way to let everyone in the family backup their important files. with the advent of OSX 10.5, backing data up might become so easy that this feature becomes very compelling.
Call home
The ability to call a ABS via my laptop modem and connect to the home network is a potentially neat feature. If you see a need to do it (and don't own a "Snow" model that can also do this once you upgrade to firmware 2.04 and higher), then searching for a "Extreme" ABS is probably a good idea. Someone who is security conscious would probably stick to "dialing-in" via SSH instead, however.

Since Apple integrated this feature into the "Snow" line of ABS' with the 2.04 Airport Software upgrade, only "Graphite" owners would benefit from a upgrade then. See this link from Apple with more info on the subject (Thanks Fabien Octave and Winston Weinmann!)
Bridging and Relaying
Starting with the "Extreme" ABS, Apple unfurled a system it calls Wireless Distribution System (WDS), commonly known as bridging and relaying. WDS allows base stations to relay information not only to adjacent computers but to other base stations as well. Thus, you could set up one main base station that feeds many other base stations wirelessly. Below is a hypothetical 4 base station network.

Airport Base Station Bridge


Once set up, your ABS' will talk to each other and route traffic from station to station. This feature is especially relevant for those of us who live in old homes or rent and don't want to poke holes in the walls unless we absolutely have to. However, there is no free lunch.

Keep in mind that the maximum speed you'll encounter is always limited by the worst bottleneck in the system. For instance, the speed of the connections between base stations is inversely proportional to the distance between them. Thus, even "Extreme" ABS' will only talk at 1MBit/s with each other if they're far apart (i.e. 54x lower than their maximum theoretical speed). Under such circumstances, multiple remote base stations could saturate the link between the main base station and the relay, causing massive slow-downs.

A "Daisy-Chain" topology is possible. On the other hand, few of us will need a "Daisy-Chain" longer than what Apple is supporting explicitly. Yet, such a chain is a great feature for those of us who rent apartments, live in houses where laying cable is difficult, etc.

Graphite and Snow base stations cannot relay signals or be a receiver. However, extreme and express base stations can be configured to to act as relays and receivers for Graphite and Snow base stations. In this instance, the Graphite or Snow would be the ABS connected to the internet, with all other ABS' cascading from it. Setting this up is fiddly because you have to configure the bridges to connect to an ABS via a MAC address. Plus, the speeds of the network are constrained by the slowest ABS in the link.

Way back when, Karlnet developed TurboCell for Graphite ABS', which mimics some WDS functionality. However, base stations with the TurboCell software can only be configured via a Windows machine, and base stations can only act as bridges, not relays. Considering the extra expense and trouble associated with setting up such a system and the many other added benefits of a Extreme/Express base stations, I'd buy a Extreme/Express base station instead of going this route.
Universal Power Supply
One of the reasons that the "Graphite" base stations failed en-masse was the design decision to feature an internal power supply in addition to the external one. The benefit of this design was that with a little tweaking you could create a power-over-ethernet (PoE) capable router at low cost (i.e. high profit). This is an exciting feature for those that like to place ABS' in remote locations w/o power jacks.

However, an internal power supply represents an additional failure point, it adds hea. Worse, Apple did not ship a universal power supply with ABS' until the "Extreme" generation. Thus, anyone who wanted to travel with an ABS had to either get a transformer for the power supply, buy a new power supply locally, or build their own 12VDC universal power supply. I built my own... but the power supply that comes with the "Extreme" and "Express"base stations offers a very compact package with a universal DIN connector that is easy to find worldwide. The Express base station takes the concept to its logical conclusion, featuring a full-fledged base station in a tiny package.
Music Server
One of the interesting features built into the Airport Express is the music server. In another nod towards the tight integration between Apple hardware and software, the Airport Express allows you to connect your stereo to your computer w/o any wires. Thus, you can listen to your tunes and control what is played where with only a few limitations. The output is both optical (i.e. digital) and analog, and its mode depends on what plug you use in the Express. Very, very cool!

Conclusion:

So, should you upgrade?

Since its introduction, Apple has matured the new technologies found in the Airport "Extreme" base stations. Thus, there are some compelling features like WPA security, IPSec-compliance, USB print-sharing, allegedly peaceful 802.11b&g co-existence, no more LAN/WAN bottle-necking, bridging and relaying, etc. that are not found on previous base stations. However, as mentioned before, some of these features are only available if you are using relatively recent Apple hardware and software.

Office environments are the most likely beneficiaries of the Airport "Extreme/Express" base station features - it's ready for prime time and much less expensive than Cisco solutions costing far more. Even better, Apple has finally released Windows-based Admin utilities for the "Extreme/Express" series so that (typically Windows-centric) network administrators have even fewer excuses to nix Apple-sourced equipment.

Do not discount using wireless hardware made by manufacturers other than Apple, if you don't mind rolling up your shirtsleeves a bit. My Frankensteinian "Graphite" base station served me well until it was killed by a lightning strike: It had a upgraded power supply, improved ventilation, its range had been extended, and it even had a universal power supply. RIP, old friend. Nowadays, I use an Extreme-n base station and a D-Link router.