NETWORK COMPONENTS OF A LAN

Network Components of a LAN

Any network requires four components so that the nodes within it can communicate with each other and exchange information. These components include the following:

1. The transmission medium over which the data is exchanged
2. Rules and standards or protocols that facilitate the communication on the network
3. Software components in the form of NOS and management applications
4. Hardware devices that make up the network

Transmission media and protocols have already been covered in the previous articless. This section consists of the hardware components that are used in a LAN. These components include the following devices:

• Media connectors
• Network Interface Cards
• Repeaters
• Hubs
• Bridges
• Switches

Media Connectors

Media connectors are devices that connect a node to the transmission medium. They correspond to the Physical layer of the OSI reference model.

The commonly used media connectors include the following:

• British Naval Connectors (BNCs): These connectors connect coaxial cables to the node. These connectors are commonly used to connect nodes in a bus topology.
• T-Connectors: These connectors connect a network card of a PC to a network through cables.
• RJ-45 connectors: These connectors connect a PC to the network socket in the wall.
• DB-9 connectors: These connectors are used with different interfaces, such as video interfaces.
• DB-25 connectors: These connectors are used in serial connections and parallel interfaces, such as printers.

Network Interface Cards

Network Interface Cards (NICs) are the internal components of nodes and connect each node to the network. NICs operate in the Data Link layer of the OSI model. As a result, they perform the functions corresponding to this layer. They supply the hardware or physical address to each node on the network.

Repeaters

The information traversing through the transmission media on a network is known as a signal. Each medium has a maximum range to carry data reliably. While traversing, the signal undergoes weakening, degradation, and distortion because the length of the network segment increases. As a result, the transmission media restricts the network segment's length.

This problem is overcome by the use of a hardware device known as repeaters. Repeaters amplify and regenerate the signal from one node to another on a network. As a result, repeaters allow you to extend the effective length of the transmission media. A repeater does not filter or interpret the signal. It only repeats or regenerates the signal. The repeaters operate at the Physical layer of the OSI reference model. If the distance between the segments to be connected is very large, multiple repeaters may be required.

The following figure shows the extension of a network segment between two floors of the same building and two different buildings using repeaters.

Network Setup Using Repeaters

Hubs

Hubs are the central point of connection on a network because they allow multiple nodes and devices to be attached to them at the same time. The point where a node or a network device is attached to the hub is referred to as a port.
Based on the number of ports, hubs can be 8-port, 10-port, 16-port, 24-port, and 32-port. Hubs with a higher port capacity are also available in the market.

The following figure shows a hub:

Network Setup Using Hub

Hubs are of the following types:

• Passive hubs: These hubs do not regenerate the signals that they receive. In addition, the signals are sent to all devices that are connected to them.
• Active hubs: These hubs are capable of signal regeneration. However, they also forward the signals that they receive to all the nodes attached to them.
• Intelligent hubs: Apart from signal regeneration, these hubs are capable of basic management-related activities, such as gathering statistics about network traffic and collisions. In addition, the signal that passes through the hub goes to the destination node and the other nodes do not receive the signal. As a result, these hubs actively participate in reducing network traffic.

Bridges

Bridges are devices to connect network segments to each other. Bridges not only extend a network, but also filter unnecessary traffic on the network.

In a large bus setup, network traffic is very high because the data packets are sent to all the nodes attached to the bus. As a result, excessive traffic is generated, which results in the low performance of the setup. The network device, bridge, is used to overcome this problem. The bridge operates on the MAC sublayer of the OSI Data Link layer.

The bridge between the two segments examines each packet for its destination information and forwards only those data packets that are specific to other segments instead of sending all the data packets. This helps reduce the network traffic between the two segments and the overall network traffic. The segregation of the network into segments and their connectivity by bridges enables the smooth functioning of the network in the event of a breakdown of a particular segment. The following figure shows the use of bridges to manage network traffic.

Network Setup Using Bridge

Bridges cannot join dissimilar network segments because it needs the physical address of the device to send the data packet. The physical address is the function of the Data Link layer that uses different protocols on each type of network.

Switches

Switches are intelligent network devices that provide universal connectivity. At the same time, switches make efficient use of network resources, especially transmission media and their bandwidth.

On receiving data packets, instead of forwarding the packets to all connected nodes or segments, switches forward the packets only to the node that is the intended recipient of the packets. As a result, switches prevent network bandwidth from being wasted.

Switches are capable of basic network management activities, such as gathering statistics about network traffic and collisions. In addition, switches can also perform advanced management activities, such as selecting the optimal path for signal delivery within a network. As a result, switches play an active role in bringing down the overall network traffic.
Switches can operate at the Data Link layer, the Network layer, or both. The switches that operate at both the Data Link layer and the Network layer are known as multilayer switches. The switches perform both the switching and routing function.

NB: Bandwidth is the range of frequencies that a signal, such as analog or digital, can occupy over a specific transmission medium. Bandwidth is measured in bits of data per second (bps) for a digital signal, while it is measured in kilohertz (kHz) for an analog signal.