Technical Basics; Wireless Networks In Accordance With The Ieee 802.11 Standard; Ad Hoc Mode - ELSA LANCOM Wireless L-2 Manuel De L'utilisateur

Technical basics

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Technical basics
This chapter is a short introduction into the technology used by your device. Network
professionals will find themselves just skimming these pages, but novices will find this
section to be very helpful for understanding the technical terms and processes.
Wireless networks in accordance with the IEEE
802.11 standard
The units of the ELSA LANCOM Wireless series comply with the IEEE 802.11 standard.
This standard is a supplement of the existing IEEE standards for LANs, of which IEEE
802.3 for Ethernet is the best known. In fact, wireless networks that comply with 802.11
can easily be connected to existing Ethernet networks. This is the most important
function of the ELSA LANCOM Wireless units. With the exception of a couple of
additional parameters, wireless adapters that comply with 802.11 are seen by the
computer as a normal Ethernet card. This means that you can also use any protocol that
you would otherwise use in a wired Ethernet (IP, IPX, NetBIOS,...) on an 802.11 wireless
network; the only difference is that there's no need for wires between the computers!
The range of wireless LAN systems is limited as the IEEE standard only covers the
definition of LANs; a typical line-of-sight range would be under 300 meters, with
considerable reductions in range due to building walls. The group of wireless LAN
stations directly within one another's range is generally referred to as a cell.

Ad hoc mode

The IEEE standard makes provision for two operating forms that differ with regard to the
security and range of such wireless LANs.
A wireless LAN in ad hoc mode consists of a single cell which is 'closed' from the
Ethernet vantage point, i.e. an external connection is only possible by routing
superordinate protocols. An example for such an element would be a ELSA LANCOM
Wireless IL-2 that serves as an Internet access router for all other stations via its ISDN
port. Ad hoc networks tend to be spontaneous, for example when a workgroup would
like to network its workstations for data exchange purposes. Workstations can enter and
leave the network as required; there is no expressly designated node that must be
present at all times. A special authentication process is not required, or for that matter
possible, because of the lack of a central station to monitor the participants.
But what happens when a workgroup in a neighboring office has the same idea and also
sets up a network? While normal Ethernets would consist of two wired physical
structures without connections between them, it's not quite so simple to lock up radio
waves to prevent interference. This problem is avoided in that every IEEE wireless LAN
ELSA LANCOM Wireless