Operation Manual

Technical basics

ELSA LANCOM Wireless

English

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 network according to the IEEE-802.11

standard

The

ELSA LANCOM Wireless

series devices conform to the IEEE-802.11 standard. This

standard is a supplement to the current IEEE standards for LANs, with IEEE 802.3 for

Ethernet being the most well-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