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Unit 6: Business Networks and Telecommunications

LAN users can select personal files that they want co-workers to see, such as engineering drawings, Notes
department plans, contracts, or drafts of memos. Co-workers can look at these files without
delays for printing paper copies. LAN can be used to transmit and manage electronic mail and
messages.

LAN also provides access to shared databases. Figure 6.12 shows a LAN system that is set up for
this purpose because it contains a file server for retrieving data requested by the workstations.
The file server is linked to a disk that contains shared databases, such as the firm’s customer list
and telephone directory. When a workstation needs data in a shared database, it sends a request
message to the file server, which performs the retrieval from the disk and sends the data to the
requesting workstation. This arrangement avoids maintaining redundant copies of data. In
addition to not wasting storage, having the databases in one place avoids problems with
inconsistent data.

Figure 6.12: The Functioning of LAN
Workstations File server

Fax Laser printer

Instead of storing separate copies of spreadsheet or work-processing software at each workstation,
the LAN can deliver a temporary copy of processing software to each workstation. Handling
software this way assures that everyone uses only the latest version of the software. Upgrading
to a new software version involves only one replacement instead of finding and replacing each
copy. This approach also reduces the number of copies of the software that must be purchased.

Example: If no more than 10 out of 25 people on a LAN use a spreadsheet at the same
time, the firm can purchase a license for 10 copies instead of 25, and can use the LAN to monitor
the number of copies in use.
Intermediate nodes (i.e. repeaters, bridges and switches) allow LANs to be connected together
to form larger LANs. A LAN may also be connected to another LAN or to WANs and MANs
using a Router1. LANs allow users to share resources on computers within an organisation, and
may be used to provide a (shared) access to remote organisations through a router connected to
a Metropolitan Area Network (MAN) or a Wide Area Network (WAN).
A device that determines the next network point to which a data packet should be forwarded
enroute toward its destination. The router is connected to at least two networks and determines
which way to send each data packet based on its current understanding of the state of the
networks it is connected to. Routers create or maintain a table of the available routes and use this
information to determine the best route for a given data packet.

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