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● fax modem bit rates up to 14.4 Kbps
The modem is connected to an internal USB port and is a vendor-specific USB device. The modem driver
controls the modem hardware and presents a virtual serial port to the operating system and applications.
Applications that bypass the operating system’s modem driver and communicate directly with the SCC will
not work properly.
Note: 56 Kbps technology refers to download speeds only and requires compatible modems at server sites.
Other conditions may limit modem speed. FCC limitations allow a maximum of 53 Kbps during download
transmissions.
AirPort Extreme
The PowerBook G4 17-inch computer supports AirPort Extreme, a fully-integrated, internal wireless LAN
module based on the IEEE draft specification of the 802.11g standard. By communicating wirelessly with a
base station, AirPort Extreme can be used for internet access, email access, and file exchange. A base station
provides the connection to the Internet or the bridge between the wireless signals and a wired LAN or both.
The AirPort Extreme Base Station has connectors for a wired LAN, a DSL or cable modem, or a standard
telephone line using the optional 56K modem that is built-in on some models.
AirPort Extreme transmits and receives data at speeds up to 54 Mbps, comparable to wired networking
speeds. Airport Extreme is alsocompatible withother devices that follow the IEEE 802.11b standard, including
PC's. For more information about compatibility, see the reference at “Wireless Networks” (page 63).
Note: As is the case with the existing IEEE 802.11b standard, actual data throughput speeds will be lower
than the indicated maximum connection speeds. Inherent in wireless LAN systems, bandwidth overhead is
required for wireless routing, scrambling, security error correction, and other processes.
Data Security
AirPort Extreme has several features designed to maintain the security of the user’s data.
● In 802.11b mode, the system uses direct-sequence spread-spectrum (DSSS) technology that uses a
multi-bit spreading code that effectively scrambles the datafor any receiver that lacks the corresponding
code.
● The system can use an Access Control List of authentic network client ID values (wireless and MAC
addresses) to verify each client’s identity before granting access to the network.
● When communicating with a base station, AirPort Extreme uses 64-bit and 128-bit WEP encryption to
encode data while it is in transit. Additional security features may be available via firmware upgrades as
802.11b standards are ratified by IEEE or as the 802.11g draft standard matures.
● The AirPort Extreme Base Station can be configured touse NAT (Network Address Translation), protecting
data from Internet hackers.
AirPort Extreme 31
Legacy Document | 2003-03-01 | © 2003 Apple Computer, Inc. All Rights Reserved.
CHAPTER 3
Devices and Ports