AirPort
From Wikipedia, the free encyclopedia
AirPort is a local area wireless networking system from Apple Computer based on the IEEE 802.11b standard (also known as Wi-Fi) and certified as compatible with other 802.11b devices. A later family of products based on the IEEE 802.11g specification is known as AirPort Extreme, offering speeds up to 54 megabits per second and interoperability with older (802.11b) products.
AirPort and AirPort Extreme in common usage can refer to the protocol (802.11b and 802.11g, respectively), the expansion card or the base station.
In Japan, AirPort is known as AirMac due to trademark conflicts.
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[edit] Overview
AirPort debuted on July 21, 1999 at the Macworld Expo in New York City with Steve Jobs picking up an iBook supposedly to give the cameraman a better shot as he surfed the Web—the applause quickly built as people realized there were no wires. The initial offering included an optional expansion card for Apple's new line of iBook notebooks, plus an AirPort Base Station. The AirPort card (a repackaged Proxim—ORiNOCO Gold Card PCMCIA adapter) was later added as an option for almost all of Apple's product line, including PowerBooks, eMacs, iMacs, and Power Macs. Only Xserves do not have an AirPort card option. The original AirPort system allowed transfer rates up to 11 Mbit/s and was commonly used to share Internet access and files between multiple computers.
On January 7, 2003, Apple introduced AirPort Extreme, based on the 802.11g specification. AirPort Extreme allows theoretical peak data transfer rates of up to 54 Mbit/s, and is fully backward-compatible with existing 802.11b wireless network cards and base stations. Several of Apple's current desktop computers and portable computers, including the MacBook Pro, MacBook, Mac mini, and iMac ship with an AirPort Extreme card as standard (as of May 2006). All other modern Macs have an expansion slot for the card. AirPort and AirPort Extreme cards are not physically compatible: AirPort Extreme cards cannot be installed in older Macs, and AirPort cards cannot be installed in newer Macs. The original AirPort card was discontinued in June 2004.
On June 7, 2004, Apple released the AirPort Express Base Station as a lower-priced, more mass-market alternative to the AirPort Extreme Base Station.
Although both AirPort and AirPort Extreme cards are available only for Macintosh computers, all AirPort base stations and cards are fully compatible with third-party base stations and wireless cards; so long as they conform to the 802.11b or 802.11g networking standards. Because of this interoperability, it is not uncommon to see wireless networks composed of several types of AirPort base station serving both old and new Macintosh, Microsoft Windows, and even Linux systems. Apple's software drivers for Airport Extreme also support some Broadcom-based PCI Wireless adapters when fitted to PowerMac computers.
[edit] Base stations
An AirPort base station is used to connect AirPort-enabled computers to the Internet, each other, a wired LAN, and/or other devices.
[edit] AirPort
The original base station (known as Graphite) featured a modem and an Ethernet port. It was based on the Lucent WaveLAN PC Card and used an embedded 486 processor. It was released July 21, 1999. The Graphite Airport Base Station is functionally identical to the Lucent RG-1000 wireless base station.
A second generation model (known as Dual Ethernet or Snow) was introduced on November 13, 2001. It added a second Ethernet port, allowing it to share a wired network connection with both wired and wireless clients. Also new was the ability to connect to America Online's dial-up service—a feature unique to Apple base stations. This model was based on Motorola's PowerPC 860 processor.
[edit] AirPort Extreme
The AirPort Base Station was discontinued after the AirPort Extreme Base Station was announced on January 7, 2003. In addition to providing wireless connection speeds of up to a maximum of 54 Mbit/s, it adds an external antenna port and a USB port. The antenna port allows the addition of a signal-boosting antenna, and the USB port allows the sharing of a USB printer. A connected printer is made available via Bonjour's "zero configuration" technology and IPP to all wired and wireless clients on the network. A second model lacking the modem and external antenna port was briefly made available, but then discontinued after the launch of AirPort Express (see below). On April 19, 2004, a third version was introduced that supports Power over Ethernet and complies to the UL 2043 specifications for safe usage in air handling spaces, such as above suspended ceilings. All three models support the Wireless Distribution System (WDS) standard.
An AirPort Extreme base station can serve up to 50 wireless clients at once and thus, is more suitable for a corporate environment than the AirPort Express. All AirPort Extreme models use an AMD Alchemy Au1500 processor which is based on the MIPS architecture.
The Airport Extreme base station product line was discontinued by Apple in the European Union from 30 June 2006, citing non-compliance with the Restriction of Hazardous Substances Directive.
[edit] AirPort Express
The AirPort Express is a simplified and compact AirPort Extreme base station allowing only up to 10 networked users with a new feature called AirTunes. It did not replace the AirPort Extreme base station. It was introduced by Apple on June 7, 2004 and includes an analog/optical audio mini-jack output, a USB port for remote printing, and a single Ethernet port. AirTunes allows an AirPort-enabled computer with the iTunes music player to simultaneously send a single stream of music to multiple (up to three) stereos connected to an AirPort Express. The AirPort Express can be used to extend the range of existing AirPort Extreme networks by using WDS-bridging,[1] which allows AirTunes functionality (as well as internet access, file and printer sharing, etc.) to be extended across a larger distance and multiple wired and wireless clients.
The main processor in the AirPort Express is a Broadcom BCM4712KFB wireless networking chipset. This has a 200 MHz MIPS processor built in. The audio is handled by a Texas Instruments PCM2705 digital-to-analog converter.
Another use of the USB port is to control AirTunes using a Keyspan USB-enabled infrared remote control.
The AirPort Express's streaming media capabilities use the Apple's Remote Audio Access Protocol (RAOP), a variant of RTSP/RTP. Currently, the AirTunes system is not compatible with the Apple Remote's volume buttons. Likewise, AirTunes will not stream a video's audio.
The device can be used as an Ethernet-to-wireless bridge, but only on wireless networks that supports WDS.
[edit] Security
AirPort and AirPort Extreme support a variety of security technologies to prevent eavesdropping and unauthorized network access. Cryptography plays a major role since all wireless networks are inherently vulnerable to eavesdropping, unlike wired networks which can, in most cases, be physically secured.
The original family of AirPort base stations, like most other Wi-Fi products, used 40-bit or 128-bit Wired Equivalent Privacy (WEP). AirPort Extreme and Express base stations retain this option, but also allow and encourage the use of Wi-Fi Protected Access (WPA) and, as of July 14, 2005, WPA2.
Generally, WEP is considered "broken". In March 2005, a demonstration by the FBI showed that they could crack a WEP key in 3 minutes using freely available tools from the internet, although as early as 2001 holes were being found in the WEP protocol.
In response to mounting concern over the insecurity of WEP, the WPA standard was made available in June 2003 as an intermediate solution until a more permanent and secure protocol could be developed. This new standard, known as WPA2, or IEEE 802.11i, was ratified on June 24, 2004 and uses the Advanced Encryption Standard (AES).
AirPort extreme cards, using the Broadcom chipset, have the MAC layer in software. The driver is closed source apparently because of the ability to impinge upon military radio frequencies.
[edit] See also
[edit] External links
- AirPort Extreme at Apple.com
- AirPort Express at Apple.com
- AirPort Support at Apple.com
- HOWTO-Airport Extreme working under GNU/Linux
- Designing AirPort Networks (PDF)
- Managing AirPort Extreme Networks (PDF)
- AirPort Card Revisions
- AirPort Base Station Experiences
- JustePort - 3rd-party Apple Express client
- raop-play - 3rd-party Apple Express client for Linux with graphical interface
- How-to: Streaming to the Airport Express under Linux - Description on how to use raop_play with the Amarok audio player under Linux
- HOWTO: Wireless Audio with Airtunes PSP Remote Control - Squidoo Lens focusing on creating a wireless remote controlled music server for the audiophile
- Evolution of the ABS
- Airfoil, commercial software to allow Airport Express to broadcast output from other programs than iTunes.
| Apple hardware since 1998 | |
|---|---|
| Consumer Macs: | iMac | iMac G3 | iMac G4 | iMac G5 | iMac Core Duo | iMac Core 2 Duo | Mac mini | eMac | iBook | MacBook |
| Professional Macs: | Power Macintosh G3 | Power Mac G4 | Cube | Power Mac G5 | Mac Pro | Xserve | PowerBook G3 | PowerBook G4 | MacBook Pro |
| iPods: | iPod | iPod mini | iPod photo | iPod shuffle | iPod nano |
| Accessories: | AirPort | iSight | Cinema Display | Xserve RAID | Mighty Mouse | iPod Hi-Fi |
| Italics denote discontinued products | |
