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Working with the notebook
42 A26391-K144-Z120-1-7619, edition 2
Ad hoc mode
A wireless LAN in the ad hoc mode, also called peer-to-peer mode, consists of a single closed cell.
Ad hoc wireless networks result when a workgroup comes together with its systems and would like
to interconnect these for data exchange. Any number of systems can be added to this type of
network and can leave it again.
So that several ad hoc wireless networks do not interfere with each other in radio traffic, there is a
unique network name, the SSID (Service Set Identifier). The SSID is used for addressing so that a
data packet can always be assigned to a certain cell.
If you want to join an existing cell, you require the network name (SSID), which you enter in the
settings for the network card. The driver searches for a wireless network with this identifier during
start-up. When the network card has found a wireless network, it connects to it and you can
communicate with the systems in this wireless network. If two cells are very closed to each other,
the channels of these networks should lie 4 to 5 channels apart to avoid malfunctions.
Infrastructure mode
In the infrastructure mode, a base station, referred to as an access point, exists in addition to the
mobile stations. In the infrastructure mode the access point assumes the function of a "guard". In
contrast to the adhoc mode, each system must log on to the AccessPoint before it is allowed to
exchange data in the cell.
Another task of the access point is the connection of the cells with a cable-connected Ethernet. As
due to the logon requirement, the access point knows at all times exactly which stations are on the
radio side, it can decide exactly which data must be sent to it and which don't. This process is also
referred to as bridging.
The range of a wireless network can be increased with several AccessPoints. The AccessPoints
have the same SSID for this purpose. When a system enters the wireless network, it searches
among the reachable access points for the one with the strongest signal and logs on there. Two
systems logged on to different AccessPoints communicate with each other in this way, even when
they are not within direct radio reach. If a system also continuously monitors the radio situation after
the logon, it can detect how the signals from an access point become weaker and those of another
become stronger, and can then log on to the stronger one without the user noticing. This procedure
is referred to as roaming.
Port Replicator
The Port Replicator (also available as an accessory) is a docking device with which you can quickly
connect your notebook to your peripheral devices. Among other things, the Port Replicator is
equipped with the standard ports for serial data transmission, printer, monitor, audio, mouse and
keyboard.
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Additional information on the Port Replicator and on the various external devices that can
be connected to it is contained in the in the chapter entitled "Connecting external
devices".