Planet WL-3560 — основы беспроводных сетей: Вопросы и ответы о технологиях [18/19]

Appendix

This section provides some technology Q&A. Read the description below to know more about

the wireless network.

ü What is the difference between 54Mbps and 11Mbps wireless products? What’s the

benefit of 54Mbps Wireless Access Point?

The 54Mbps is made possible by the new modulation method called OFDM, which is

different from the current CCK modulation method for 11Mbps. The 54Mbps wireless

products also operate in the 2.4GHz ISM band and they are backward compatible with

11Mbps wireless products.

ü What is ISM band?

The FCC and their counterparts outside of the U.S. have set aside bandwidth for unli-

censed use in the ISM (Industrial, Scientific and Medical) band. The 2.4GHz unlicensed

ISM band is available worldwide, which presents the opportunity for the global market of

802.11b and 802.11g high speed wireless products.

ü What is Ad-Hoc?

An Ad-Hoc integrated wireless LAN is a group of computers, each with a WLAN adapter,

Connected as an independent wireless LAN. Ad-Hoc wireless LAN is applicable at a

departmental scale for a branch or SOHO operation.

ü What is Infrastructure?

An integrated wireless and wired LAN is called an Infrastructure configuration. Infra-

structure is applicable to enterprise scale for wireless access to central database, or

wireless application for mobile workers.

ü What is BSS ID?

A specific Ad-Hoc LAN is called a Basic Service Set (BSS). Computers in a BSS must

be configured with the same BSS ID.

ü What is Roaming?

Roaming is the ability of portable computers, e.g., Packet PC and notebook, to have

consistent and continuous data transmission/reception throughout an area covered by

more than one Wireless Access Point. In order to achieve seamless connectivity, all

the wireless clients and Access Points must be set to use the same SSID. When a

user walked out of the coverage area of one AP into another, the wireless client network

device will automatically reestablish connection with the new AP.

ü What is a MAC Address?

The Media Access Control (MAC) address is a unique number assigned by the manu-

facturer to any Ethernet networking devices, e.g. a network adapter, that allows the

network to identify it at the hardware level. Unlike IP addresses, which can be