4.1. The network devices.
Mainly represents the point of access to all the features of a computer application and an operating system, in particular to computing resources (mail, Office Automation, web applications, but also printer, document scanner, keyboard...).
4.2. The network interface card (NIC)
This adapter is needed to connect a workstation to a server or other workstations. The network adapter is the interface between the computer and the network cable. The function of a NIC is to prepare and send control data on the network.
The network adapter has usually two indicator lights (LEDs):
o The Green LED corresponding to the supply of the card;
o The orange LED (10 Mb/s) ...view middle of the document...
Each thread wrapped around the other serves as a protection against interference. There are two types of twisted pair: the twisted pair shielded and unshielded twisted pair the only difference between these two types of twisted pair is the presence of a coating shielded protecting better interference. An important advantage of the IO Base-T is that it is easier to troubleshoot than a bus network. The network cables leave a dispatcher for go to the nodes of the network. If one of these cables is switched off or short-circuited. The node is disconnected but the rest of the network is not affected.
Five categories of twisted pairs exist:
o Category 1: it's the simple telephone wire.
o Category 2: This cable is intended for (less than 4 Mbps) average speed transmissions.
The next three categories provide better quality cables and have the following characteristics: they have three cables all 30 cms. Two pairs should not have the same sense of cables.
o Category 3: This cable is often chosen in local networks. It is used for transmissions up to 10 Mbps.
o Category 4 this cable is used for the transmissions at 16 Mbps.
o Category 5: this cable is intended for very fast networks. With the shield, the maximum transmission speed is 100 Mbps.
o The simplest and the cheapest made up of metallic pairs ((0.2 to 1 mm).
o Easy to install and team virtually everything pre-wired,
o Average buildings most commonly used for the phone (mid-frequency).
o Major weakening without shielding (UTP cable).
o Advantages: bitrate important short distance (100Mbps on ~ 100 m).
o Is suitable for local area networks where machines are just scattered.
2. Coaxial cable
Sometimes called coaxial cable BNC cable (a form of bayonet connector is used for the coaxial cable end), is a relatively rigid copper drowned in a cover made of insulating plastic, itself surrounded by a second wire mesh consisting driver playing the role of screen with regard to interference. If you need a bandwidth and a noise protection more important than those provided by the twisted pairs, without wanting to optical fiber, then the coaxial cable is a good choice.
In addition, this technology uses significantly less cable star that a network using a topology as does the IO Base-T. Then, it does not require the use of a hub. Therefore, you made the economy of space, power and money since the network nodes connect directly with each other. However if the string is cut, the network crashes. Remember that the maximum distance between two elements for insulated wire without repeaters is 100 metres and 185 metres to the BNC.
- avoids disturbances due to external electromagnetic noise,
- Three types of cables: - (Thin and Thick Ethernet) to baseband networks,
- (CATV) for broadband and video networks,
- (IBM) terminals 3270)
- Advantages: the bit rate can reach 25 Mbps over long distances and the amplifiers must be arranged all 4.5 km for telephony (MPX),