Active and Passive network equipment
A router ensures the transmission of information between two separate networks by choosing the best path. It allows for the optimal routing of data packets between different networks. Routers generally integrate a small-capacity switch. ISP (Internet Service Provider) "boxes" contain a router, a switch (4 ports), an ADSL modem, and sometimes a Wi-Fi access point. These "boxes" allow the user's local network to be interconnected to the WAN. A router generally has (at least) two IP addresses: one for the local LAN and another for its connection to the second network (LAN or WAN). The devices listed above are classified as active equipment, whereas cables, enclosures, cords, and patch panels are classified as passive equipment.
To connect the various entities of a network, several physical data transmission media can be used. One of these possibilities is the use of cables. There are many types of cables, but the following are generally distinguished: Coaxial cable: This consists of two cylindrical conductors separated by an insulating material (as in antenna cable). It can be used for lengths of 185 m (10 B 2 cable) or 500 m (10 B 5 cable).
However, the data rate is limited to 10 Mbps (BNC cable). BNC connectors and impedance caps are used. Coaxial cable is used in bus networks. Twisted pair: This is an improved version of the telephone cable. It is inexpensive, but performance decreases over distance.
It is susceptible to electrical interference (RJ45 cable) and is used with a hub. Data rates can reach 100 Mbps (100 BT cable) or 1000 Mbps (1000 BT cable). Distances are limited to 100 m (beyond this, there is a significant risk of data loss).
(LAN—Ethernet card)
It is installed on every computer (including the server) on the network and on network printers. It allows computers to communicate with each other (by managing the data link layer of the OSI model). It handles collision detection on an Ethernet network: a collision occurs when two computers send information simultaneously. Network cards have a unique physical address assigned by the manufacturer.
MAC (Media Access Control)
It is essential because it allows a machine to be recognized by other machines on the network. The network card is an expansion card connected to a bus (usually PCI) and featuring an RJ45, BNC, or fiber connector. Some network cards (see photo) are multipurpose (combo) cards, which include a BNC connector for connecting the workstation to a bus network and an RJ45 connector for connecting the workstation to a
star Network Topology
The Star Network: Network devices are connected to a central hardware system (the node).
This node's role is to ensure communication between the various network devices. Particularly used by current RJ45 Ethernet networks, it now applies to the majority of networks.
When all stations are connected to a switch, we speak of a star topology. The network nodes are all connected to a central node. In this topology, all hosts are interconnected using a switch (until a few years ago, it was a hub): a sort of power strip for network cables placed at the center of the star. The stations transmit to this hub, which forwards the data to all other network ports (hub) or only to the destination switch. The cable between the different nodes is referred to as twisted pair
because the cable that connects the machines to the switch generally consists of four twisted pairs of wires and ends in connectors called RJ45.
Bus network: is a communication architecture where hardware is connected via a bus shared by all users.
Bus networks allow for the simple connection of multiple devices but pose problems when two machines want to transmit data simultaneously over the bus. Systems using a bus topology normally have an arbiter that manages access to the bus.