The 802.11 Standard Defined
In 1997, after seven years of work, the IEEE published 802.11, the first
internationally sanctioned standard for wireless LANs. With 802.11b (2G)
and 802.11a (3G) WLANs, mobile users can get Ethernet levels of performance,
throughput, and availability. This chapter defines the standardsbased
technology that allows administrators to build networks that seamlessly
combine LAN technologies to best fit their business and user needs.
1. The 802.11 standard defines two modes: infrastructure mode and ad
hoc mode. In infrastructure mode, the wireless network consists of
at least one access point connected to the wired network infrastructure
and a set of wireless end stations. This configuration is called a
basic service set (BSS). An extended service set (ESS) is a set of two
or more BSSs forming a single subnetwork. Since most corporate
WLANs require access to the wired LAN for services (file servers,
printers, Internet links) they will operate in infrastructure mode.
2. Ad hoc mode (also called peer-to-peer mode or an Independent Basic
Service Set, or IBSS) is a set of 802.11 wireless stations that communicate
directly with one another without using an access point or
any connection to a wired network. This mode is useful for quickly
and easily setting up a wireless network anywhere that a wireless
infrastructure does not exist or is not required for services, such as a
hotel room, convention center, or airport, or where access to the
wired network is barred (such as for consultants at a client site).
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