Computer networking devices are hardware components that enable computers and other devices to communicate and share resources. These devices are essential for establishing and maintaining wired or wireless networks. Each device plays a unique role in ensuring data is transmitted accurately and efficiently.

Types of Computer Networking Devices

1. Hubs

• A hub is a basic networking device that connects multiple devices in a LAN. It broadcasts incoming data to all connected devices, which can lead to inefficiencies. While switches have largely replaced hubs, they remain important to networking history.
• Hub is a very simple network connecting device. In Star/hierarchical topology, a Repeater is called a Hub. It is also known as a Multiport Repeater Device.
• A Hub operates only in the physical network of the OSI Model. Since it works in the physical layer, it mainly deals with the data in the form of bits or electrical signals. A Hub is mainly used to create a network and connect devices on the same network only.
• A Hub is not an intelligent device, it forwards the incoming messages to other devices without checking for any errors or processing it. It does not maintain any address table for connected devices. It only knows that a device is connected to one of its ports.

There are mainly two types of Hub, they are:

1. Active Hub: An Active hub is also known as a Concentrator. It requires a power supply and can work as a repeater. Thus, it can analyze the data packets and amplify the transmission signals, if needed.
2. Passive Hub: A passive hub does not need any power supply to operate. It only provides communication between the networking devices and does not amplify the transmission signals. In other words, it just forwards the data as it is.

The following are the advantages of using a Hub:

1. It is simple to implement.
2. The implementation cost is low.
3. It does not require any special system administration configuration. We can just plug and play it.

The following are the disadvantages of using a Hub:

1. It can connect devices of the same network only.
2. It uses a half-duplex mode of communication.
3. It is less secure, as it broadcasts the data packets.
4. It can be used in a limited network size only.
5. Broadcasting induces unnecessary traffic on the channel.

2. Bridges

• A bridge connects two or more networks, allowing them to function as a single network. It reduces traffic by dividing networks into smaller, more manageable segments.

There are mainly two types of Bridge, they are:

1. Transparent Bridge: Transparent bridge simply works as a transmission medium between two devices. They are actually transparent(they are present but are not functionally visible to the devices) to the networking devices.
2. Routing Bridge: Routing bridges have their unique identity, they can be easily identified by the network devices. The source station or the sender can send the data packets through specific bridges(using the unique identity of bridges).

The following are the advantages of using a Bridge:

1. It is not so complex to implement.
2. The implementation cost is medium.
3. It does not require any special system administration configuration. We can just plug and play it.
4. Improves security by limiting the scope of data frames.
5. It has the filtering capability.
6. It can be used in a large network.

The following are the disadvantages of using a Bridge:

1. It can connect devices of the same network only.
2. There is a delay in forwarding the frames due to error checking.
3. There is a need to maintain an Address table.

3. Switches

• switches are used within local area networks (LANs) to connect multiple devices, such as computers, printers, and servers. Unlike hubs, switches intelligently forward data to the intended recipient, ensuring efficient network performance.

There are mainly four types of Switches, they are:

1. Store and Forward Switch: It is the most widely and commonly used switch. It does not forward the data frames unless the frames are errorless and completely received in the switch buffer. It is reliable in nature.
2. Cut-through Switch: Cut-through switches have no error checking. Also, it starts sending the data frame to the destination node when it starts receiving it. It is unreliable in nature.
3. Fragment-Free Switch: It is a combination of store and forward, and cut-through switch. It checks only the starting 64 bytes(header information) of the data frame before transmitting the frame.
4. Adaptive Switch: It is the most advanced kind of switch which automatically chooses any of the above three switches as per the need.

The following are the advantages of using a Switch:

1. The implementation cost is medium.
2. It does not require any special system administration configuration. We can just plug and play it.
3. Improves security by limiting the scope of data frames.
4. It has the filtering capability.
5. It can be used in a large network.
6. It uses full-duplex mode of communication
7. It has multiple collision domains, so there are least or no collisions in the channel.

The following are the disadvantages of using a Switch:

1. It can connect devices of the same network only.
2. There is a delay in forwarding the frames due to error checking.
3. There is a need to maintain a Switch table.

4. Routers

• Routers are pivotal devices that connect multiple networks and direct data packets to their destination. They are commonly used to link home or office networks to the internet. Routers operate using IP addresses and protocols to ensure data is routed efficiently.
• it works on the physical, data-link, and network layer of the OSI model.
• . It is mainly an internetworking device, which can connect devices of different networks(implementing the same architecture and protocols).

A Router can be a Wireless Router, Core Routers, Edge Routers, Virtual Routers, etc.

There are mainly two types of routing performed by Routers, they are:

1. Static Routing: In Static Routing, the path for the data packets is manually set. It is generally used for small networks.
2. Dynamic Routing: In Dynamic Routing, various routing algorithms are used to find the best and shortest path for the data packets.

The following are the advantages of using a Router:

1. It can connect devices and provide routing facilities over different networks implementing the same protocol and structure.
2. Improves security by limiting the scope of data packets.
3. It has the filtering capability.
4. It can be used in a large network.
5. It uses full-duplex mode of communication
6. It has control over both the collision and broadcast domains.

The following are the disadvantages of using a Router:

1. It is very complex to implement.
2. The implementation cost is quite high.
3. There is a need to maintain a Routing table.
4. There is a delay in forwarding the packets due to error checking.
5. It requires a special system administration configuration.

5. Gateways

• Gateways act as entry points between different networks. They enable communication between systems with different protocols, ensuring compatibility and data integrity.
• A Gateway is the most intelligent device among network connecting devices, offering advanced functionality for error control, data packet routing, transmission speed, and overall operation. It serves as a crucial component in connecting different networks, often with varying protocols and architectures.
• A Gateway is also referred to as a “Protocol Converter” because of its ability to convert data packets to match the protocol requirements of the destination network. This functionality is crucial when connecting networks that operate on different communication protocols.

The following are the advantages of using a Gateway:

1. It can connect the devices of two different networks having dissimilar structures.
2. It is an intelligent device with filtering capabilities.
3. It has control over both collisions as well as a broadcast domain.
4. It uses a full-duplex mode of communication.
5. It has the fastest data transmission speed among all network-connecting devices.
6. It can perform data translation and protocol conversion of the data packet as per the destination network’s need.
7. It can encapsulate and decapsulate the data packets.
8. It has improved security than any other network connecting device.

The following are the disadvantages of using a Gateway:

1. It is complex to design and implement.
2. The implementation cost is very high.
3. It requires a special system administration configuration.

6. Modems

• Modems (short for modulator-demodulator) are devices that connect a network to the internet by converting digital signals to analog and vice versa. They are essential for accessing internet services via broadband or DSL connections.
• Based on the differences in speed and transmission rate, a modem can be classified into the following categories:
  • Standard PC modem or Dial-up modem
  • Cellular Modem
  • Cable modem

Outline

What is Transmission Media?

Transmission media refer to the physical pathways that carry data from one point to another in a network. These media can be wired or wireless, depending on the application and environment.

Importance of Transmission Media in Communication

Effective communication relies heavily on the right transmission medium. The choice of medium impacts:

• Speed: Determines how quickly data is transmitted.
• Distance: Influences the range of data transmission.
• Cost: Affects overall budget requirements.
• Quality: Impacts signal integrity and reliability.

Classification of Transmission Media

Guided Media

It is defined as the physical medium through which the signals are transmitted. It is also known as Bounded media.

Types Of Guided Media:

1. Twisted Pair Cables are one of the most commonly used types of cables in networking and telecommunications. They consist of pairs of insulated copper wires twisted together, which helps reduce interference and improve signal quality.

                                                                                                fig. Twisted pair cables.

Here are the advantages of twisted pair cables:

1. Cost-Effective: Twisted pair cables are inexpensive compared to other transmission media like coaxial or fiber optic cables.
2. Easy Installation: They are lightweight, flexible, and simple to install.
3. Wide Availability: Twisted pair cables are commonly available and used in various network setups.
4. Noise Reduction: The twisted design minimizes electromagnetic interference and crosstalk.
5. Scalability: They are suitable for short- to medium-distance communication and can be easily upgraded or extended.
6. Durability: The cables are robust enough for standard use and can withstand bending without damage.
7. Support for Analog and Digital Signals: Twisted pair cables can efficiently carry analog and digital signals.
8. Compatibility: These cables are widely supported by various networking and telecommunication devices.

Types of Twisted pair:

1.Unshielded Twisted Pair (UTP)

Unshielded Twisted Pair (UTP) is a type of cable commonly used in telecommunications and computer networking. It consists of pairs of copper wires twisted together to reduce electromagnetic interference and crosstalk between adjacent pairs. UTP cables do not have an additional shielding layer, making them lightweight, flexible, and cost-effective.

Advantages Of Unshielded Twisted Pair:

• It is cheap.
• Installation of the unshielded twisted pair is easy.
• It can be used for high-speed LAN.

Disadvantage:

• This cable can only be used for shorter distances because of attenuation.

Shielded Twisted Pair (STP)

Shielded Twisted Pair (STP) is a type of twisted-pair cable that features an additional shielding layer around the pairs of wires to protect against electromagnetic interference (EMI) and crosstalk. This shielding can be made of a metallic foil, braided wire, or both, providing extra protection in environments with high levels of interference.

Characteristics of Shielded Twisted Pair (STP)

1. Shielding Layer: STP cables have a protective layer of metal shielding, which helps reduce interference from external electromagnetic signals.

2. Better Signal Quality: The shielding ensures better signal integrity by minimizing noise and crosstalk between adjacent wires.

3. Thicker and Heavier: The additional shielding makes STP cables thicker and heavier than unshielded twisted pair (UTP) cables.

4. Higher Cost: Due to the shielding material and more complex manufacturing process, STP cables are generally more expensive than UTP cables.

5. Requires Proper Grounding: For effective performance, STP cables need proper grounding to ensure the shield can dissipate unwanted interference.

6. Less Flexible: The added shielding makes the cable less flexible, which can complicate installation in tight or complex spaces.

7. Improved Performance in High-Interference Environments: STP cables are well-suited for environments with significant electromagnetic interference, such as factories, industrial settings, or areas with heavy electrical equipment.

8. Compatibility with Networking Standards: Modern STP cables are compatible with high-speed networking standards, such as Gigabit Ethernet, while offering enhanced protection against interference.

9. Lower Crosstalk: The shielding reduces the impact of crosstalk, which is the interference between cable pairs, resulting in better overall performance.

Disadvantages

• It is more expensive as compared to UTP and coaxial cable.It has a higher attenuation rate.

Coaxial Cable

• Definition: A coaxial cable is a commonly used transmission medium, often seen in applications like television connections.
• It is called “coaxial” because it contains two conductors that are parallel to each other.
• Coaxial cables operate at a higher frequency than twisted pair cables, making them suitable for high-speed data transfer applications.

Structure of Coaxial Cable:

1. Inner Conductor:

   • Made of copper and is responsible for carrying the data signals.

2. Non-Conductive Cover:

   • Surrounds the inner conductor to provide insulation and separation from the outer conductor.

3. Outer Conductor:

   • Made of copper mesh or foil, which acts as a shield to prevent electromagnetic interference (EMI).

4. Outer Jacket:

   • A protective covering that provides durability and physical protection for the cable.

Coaxial cable is of two types:

1. Baseband transmission: It is defined as the process of transmitting a single signal at high speed.
2. Broadband transmission: It is defined as the process of transmitting multiple signals simultaneously.

Advantages Of Coaxial Cable:

• The data can be transmitted at high speed.
• It has better shielding than twisted pair cables.It provides higher bandwidth.

• Disadvantages Of Coaxial cable:

  • It is more expensive as compared to twisted pair cables.
  • If any fault occurs in the cable causes the failure in the entire network.