BASIC NOTIONS ABOUT LAN NETWORK
A local area network (LAN) is a group of devices connect in a located area in order to communicate
between them and share resources like, for example, printers. Datas are sent in packets and, for
this broadcasting, can be used several technologies. The most common LAN technology is
Ethernet, which is specified in the IEEE 802.3 standard.
Ethernet uses a topology in star where all single nodes (devices) are connected between them
trough an active network device like a switch. The number of devices connected to a LAN can
oscilate between two or several thousands.
The physical broadcasting way for a wired LAN includes twisted pair cables or optical fiber. A
twisted pair cable disposes of 8 cables (4 pairs of twisted cables) and used RJ 45 connectors
and sockets. The maximum length of a twisted pair cable is 100 m, while, for optical fiber, the
maximum length varies between 10 km to 70 km, depending on the cable type.
In general, the networks should always have more capacity that necessary. In order to prepare
a network, is a good idea to design a network that use about the 30% of the full capacity.
The majority of devices connected to the network, like a laptop or webcam, are equipped with an
Ethernet 100BASE-TX/10BASE-T interface (common named as 10/100 interface), this interface
admits as much 10Mbit/s as Fast Ethernet. The cable type of twisted pair compatible with Fast
Ethernet is Cat5.
In order to connect several devices to a LAN is necessary a switch. With this devices is possible
to use a conventional network cable instead of a crossover cable. The main function of a switch
es to send the data from a device to another device in the same network. It is an efficient method
due to the data can be enrouted froma device to another device without affect to the rest of
device in the same network.
USER MANUAL
45
