Introduction To Computer Networks

AGENDA

• Introduction
• Features
• Architecture
• Components
• Computer Network Types
• Terminologies
• Topologies

Introduction:

A computer network is a system of interconnected computers and devices that communicate with each other using wired connections, optical fibres, or wireless links. The primary purpose of a computer network is to enable resource sharing, allowing multiple devices to exchange data, access shared files, and utilise common hardware resources such as printers or storage drives.

Computer networks facilitate efficient communication and collaboration by creating a seamless flow of information between devices. Depending on the specific needs and scale of an organisation or individual users, networks can range from small, local configurations (like those within a home or small office) to vast and complex systems spanning multiple regions or even continents.

In networking technology, various types of networks serve different purposes, categorised by their size, reach, and configuration complexity. These include Local Area Networks (LANs), Wide Area Networks (WANs), Metropolitan Area Networks (MANs), and other specialised network types, each designed to meet specific connectivity needs.

By linking devices in this way, computer networks play a critical role in modern communication, supporting everything from basic data sharing to sophisticated cloud computing and internet services.

Components of Computer Networks:

A. Network Interface Card (NIC)

A Network Interface Card (NIC) is an essential hardware component that enables a computer to connect and communicate with other devices on a network. Each NIC is equipped with a unique hardware address that allows the data-link layer protocol to identify the system, ensuring data is accurately routed to its intended destination. 

NICs are classified into two main types:

1. Wireless NIC: Commonly found in modern laptops, wireless NICs establish connections using antennas and utilise radio wave technology for communication.
2. Wired NIC: Wired NICs connect devices through physical cables, facilitating data transfer over a wired medium.

B. Hub

A hub functions as a central connection point within a network, allowing multiple devices to connect. When a computer requests information, it sends that request to the hub, which then distributes it to all devices connected to it. However, hubs transmit data indiscriminately to all devices on the network, making them less efficient than more advanced networking devices.

C. Switch

A switch serves as a more intelligent alternative to a hub, grouping devices on a network for effective data transmission. Unlike a hub, which broadcasts messages to all connected devices, a switch intelligently directs messages to the specific device intended to receive them. This targeted communication enhances network efficiency by minimising unnecessary data traffic.

D. Cables and Connectors

Cables are the physical medium used for transmitting communication signals across a network. 

There are three primary types of cables:

1. Twisted Pair Cable: Known for its high-speed capabilities, this type of cable can transmit data at speeds of 1 Gbps or more.
2. Coaxial Cable: Often resembling the cables used for television installations, coaxial cables are more expensive than twisted pair cables but offer higher data transmission speeds.
3. Fibre Optic Cable: This advanced cable transmits data using light signals, allowing for extremely high-speed data transfer compared to other cable types. Due to its cost, fibre optic cabling is typically used in high-demand applications, such as government networks.

E. Router

A router is a crucial networking device that connects a local area network (LAN) to the internet. It enables communication between distinct networks and allows multiple computers to share an internet connection, effectively routing data packets between the LAN and external networks.

F. Modem

A modem serves as a bridge between a computer and the internet by connecting to existing telephone lines. Unlike other components that may be integrated into a computer's motherboard, a modem is a standalone device typically installed in a dedicated PC slot. Its primary function is to modulate and demodulate signals, facilitating internet access over telephone lines.

Uses of Computer Networks:

1. Communication: Computer networks enable seamless communication between individuals and organisations through emails, instant messaging, and video conferencing. This connectivity fosters collaboration and information exchange regardless of geographical barriers.

2. File Sharing: Networks facilitate the sharing of files and resources among users, allowing multiple devices to access and collaborate on documents, applications, and databases efficiently. This feature enhances productivity by streamlining workflows.

3. Internet Access: Computer networks provide users with access to the internet, allowing for web browsing, online research, and utilisation of various internet-based services. This connectivity is essential for accessing information and services worldwide.

4. Resource Management: Networks allow for centralised management of resources such as printers, servers, and storage devices. By connecting these resources to a network, organisations can optimise usage, reduce costs, and simplify maintenance.

5. Remote Access: Computer networks enable remote access to systems and data, allowing users to connect to their office networks from remote locations. This capability supports flexible working arrangements and enhances productivity by providing access to critical resources anywhere, anytime.

Features of Computer Networks:

1. Scalability: Computer networks can easily expand by adding new devices or connections without disrupting existing operations. This flexibility allows organisations to grow and adapt their networks according to changing needs.

2. Reliability: Networks are designed to provide reliable data transmission through redundancy and fault tolerance mechanisms. This ensures that communication remains stable and consistent, even in the event of hardware failures or network disruptions.

3. Security: Computer networks incorporate various security measures, such as firewalls, encryption, and access controls, to protect sensitive data and prevent unauthorised access. These features safeguard both network integrity and user privacy.

4. Interoperability: Networks support the integration of different types of devices and operating systems, allowing seamless communication across various platforms. This interoperability enhances collaboration and resource sharing among diverse systems.

5. Centralised Management: Computer networks enable centralised management of network resources, configurations, and security settings. This feature simplifies administration tasks and allows network administrators to monitor performance and manage resources more efficiently.

Computer Network Architecture:

Network architecture refers to the structural design of a computer or communications network. It encompasses the organisation, allocation of tasks, and management of various devices such as laptops, tablets, and servers. Essentially, it outlines how network components interact and how tasks are distributed among connected devices.

The architecture is defined by both the physical layout and the logical structure of the software, hardware, protocols, and media used for data transmission. This article will delve into network architecture, its types, the skills required to become a network architect, and more.

Types of Network Architecture:

Computer networks can primarily be classified into two types based on their architecture:

1. Peer-to-Peer (P2P) Architecture

In a P2P network, all connected computers, referred to as peers, communicate directly with one another. This architecture enables file sharing without a central server, where each computer can function as both a client and a server. P2P networks are particularly beneficial for small environments, typically accommodating up to ten computers. This setup promotes equal roles among all devices, allowing for efficient communication and resource sharing.

Advantages of Peer-to-Peer Architecture:

• Cost-effective and affordable to set up.
• Simple to manage due to minimal complexity.
• Easy installation with self-managing capabilities in modern operating systems.

Disadvantages of Peer-to-Peer Architecture:

• Security policies can be difficult to enforce consistently.
• Each peer requires individual maintenance.
• Efficiency may decrease as the network scales.

2. Client/Server Architecture

In a client/server network, a centralised server connects to multiple client computers, which are generally less powerful. The server acts as the primary resource hub, enabling clients to access shared resources. This architecture is more stable and scalable compared to P2P networks.

Advantages of Client/Server Architecture:

• Centralised resource management through a Network Operating System (NOS).
• Simplified data management and updates due to centralised storage.
• Enhanced resource control and security provided by the server.

Disadvantages of Client/Server Architecture:

• A server failure can disrupt services for all clients.
• Higher investment in hardware and software is required for server setup.
• Requires skilled personnel to manage server operations.

Types of Computer Networks:

1. Local Area Network (LAN):

A Local Area Network (LAN) connects computers and devices within a limited geographical area, such as a single building, office, or home. LANs are commonly used in businesses and educational institutions, where multiple computers need to share resources like printers and files. They typically use Ethernet cables or Wi-Fi technology for communication.

Advantages:

• High-Speed Data Transfer: LANs offer high data transfer speeds, typically ranging from 100 Mbps to several Gbps, which enhances user productivity by facilitating quick access to shared resources.
• Cost-Effective: The hardware required to set up a LAN, such as switches, routers, and network cables, is relatively inexpensive, making it an affordable option for many organisations.
• Enhanced Security: Because LANs are limited to a small area, they are generally more secure. Access control measures can be easily implemented to restrict unauthorised users.
• Easy Resource Sharing: LANs enable users to easily share files, printers, and other resources, promoting collaboration among users.

Disadvantages:

• Limited Coverage: LANs are confined to a small geographical area, making them unsuitable for connecting distant locations or multiple branches of a business.
• Maintenance Complexity: As the number of devices on a LAN increases, managing and maintaining the network can become more complex, requiring dedicated IT staff.
• Network Congestion: High traffic can lead to network slowdowns, especially if many users access the network simultaneously.

Examples:

• Home Network: A typical home network connects personal computers, tablets, and smart devices via Wi-Fi or Ethernet.
• Office Network: An office LAN connects multiple computers and printers, allowing employees to share resources efficiently.

2. Personal Area Network (PAN)

A Personal Area Network (PAN) is designed for connecting personal devices within a very limited range, typically up to 10 metres. PANs are often used to connect devices such as smartphones, tablets, laptops, and wearable technology.

Advantages:

• Convenience: PANs provide an easy and convenient way to connect personal devices, allowing users to manage and share data seamlessly across their devices.
• Low Power Consumption: Devices in a PAN, especially those using Bluetooth technology, tend to consume less power, making them energy efficient for personal use.
• Flexibility: Setting up a PAN is generally straightforward and can be done without extensive configuration, allowing users to adapt their networks quickly.

Disadvantages:

• Limited Range: The short coverage area of PANs restricts connectivity to the immediate vicinity of the user, which can be inconvenient for broader usage scenarios.
• Interference: Wireless PANs may experience interference from other electronic devices, which can disrupt connectivity and reduce performance.
• Security Risks: Due to their wireless nature, PANs can be susceptible to unauthorised access if proper security measures are not in place, such as strong encryption and authentication.

Types of Personal Area Network:

• Wired Personal Area Network: Established using wired connections like USB cables.
• Wireless Personal Area Network: Utilises wireless technologies such as Wi-Fi and Bluetooth for connectivity.

Examples of Personal Area Networks:

• Body Area Network: A network of wearable devices, such as fitness trackers and smartwatches, that monitor health metrics and communicate with a smartphone.
• Home Network: Integrates devices like computers, printers, and smart TVs within a household without requiring an internet connection.
• Small Home Office: Connects personal devices to both the internet and a corporate network using VPN, allowing for secure remote work.

3. Metropolitan Area Network (MAN)

A Metropolitan Area Network (MAN) connects multiple LANs within a specific geographical area, such as a city or large campus. MANs are often used by government agencies, educational institutions, and businesses that require reliable communication across various locations within the metropolitan area.

Advantages:

• Extended Coverage: MANs provide a larger coverage area than LANs, making them suitable for organisations with multiple branches or locations within a city.
• Efficient Resource Sharing: Organisations can share resources, applications, and data across different locations, facilitating collaboration and reducing costs.
• Improved Communication: MANs enhance communication between different organisations, such as banks, universities, and government offices, streamlining processes and services.

Disadvantages:

• Higher Cost: The setup and maintenance of MANs can be expensive due to the required infrastructure, such as fibre optic cables and advanced networking equipment.
• Complex Management: Managing connections between multiple LANs can be complex and may require specialised IT staff with expertise in network management.
• Potential for Slower Speeds: Depending on the technology used, data transfer speeds may not be as fast as those experienced in LANs.

Examples:

• Citywide Wi-Fi Networks: Some cities provide free or low-cost Wi-Fi services that connect public institutions, businesses, and residents.
• University Campus Network: A university may implement a MAN to connect multiple buildings and departments, enabling students and faculty to access resources efficiently.

4. Wide Area Network (WAN)

A Wide Area Network (WAN) spans a vast geographical area, such as states or countries, and connects multiple LANs and MANs. WANs are crucial for businesses, government agencies, and educational institutions that operate across different locations.

Advantages:

• Global Connectivity: WANs enable organisations to communicate and share data over large distances, supporting international business operations and collaborations.
• Centralised Data Management: Data is often stored centrally, simplifying access for users across various locations and reducing the need for redundant storage solutions.
• Scalability: WANs can easily expand to accommodate more users and devices across different locations, making them suitable for growing organisations.

Disadvantages:

• Security Vulnerabilities: The extensive nature of WANs can make them more susceptible to security breaches and cyberattacks due to the complexity of protecting multiple access points.
• High Setup Costs: Establishing a WAN can be costly, requiring significant investment in advanced hardware, software, and infrastructure.
• Complex Troubleshooting: Troubleshooting network issues can be challenging due to the large geographical area covered and the variety of technologies involved.

Examples of Wide Area Networks:

• Mobile Broadband Networks: 4G and 5G networks provide internet connectivity across large regions and countries, enabling mobile devices to stay connected.
• Corporate WANs: Companies with multiple offices may establish a WAN to connect their branches securely and efficiently, allowing for data sharing and communication.
• Satellite Networks: Used in remote areas where traditional wired connections are impractical, satellite networks can provide internet access and connectivity across vast distances.

5. Virtual Area Network (VLAN)

Virtual Local Area Network (VLAN) is a technology that segments a physical network into smaller, logical networks. It allows devices to be grouped together logically, even if they’re physically spread across different locations. VLANs are configured on network switches, and each VLAN is identified by a unique VLAN ID.

With VLANs, network administrators can manage network traffic more efficiently, improve security by isolating sensitive information, and reduce broadcast traffic within the network. VLANs also allow flexibility, as devices can be moved to different parts of the network without needing physical rewiring—they can just be assigned to a different VLAN.

Advantages:

• Improved Security: VLANs create isolated network segments, which can be used to separate sensitive data. For instance, accounting data can be separated from general office traffic, making it more secure.
• Reduced Broadcast Traffic: VLANs limit the size of broadcast domains. Devices within the same VLAN receive broadcast traffic, reducing unnecessary traffic across the entire network.
• Flexible Network Management: With VLANs, you can manage devices as logical groups rather than physical ones. This is particularly useful for reorganising network devices by function, department, or location without needing new hardware.
• Enhanced Network Performance: By segmenting the network, VLANs reduce congestion and improve the performance of the network since broadcast traffic is contained within individual VLANs.
• Simplified Troubleshooting: Network issues can often be isolated within a single VLAN, making it easier to identify and fix problems without affecting other parts of the network.

Disadvantages:

• Complex Configuration: Setting up VLANs requires careful planning and configuration on network switches, especially for large or complex networks.
• Inter-VLAN Routing Requirement: Communication between VLANs requires a router or Layer 3 switch, adding an extra layer of complexity and potentially increasing costs.
• Potential Security Risks (VLAN Hopping): If VLANs are not configured correctly, they can be vulnerable to attacks like VLAN hopping, where a malicious user gains access to another VLAN.
• Limitations on Broadcast Control: While VLANs reduce broadcast domains, too many VLANs or too much inter-VLAN traffic can offset these benefits, leading to network inefficiencies.
• Increased Management Overhead: Managing multiple VLANs, especially in a dynamic network with frequent changes, can require additional monitoring and maintenance.

Examples of VLAN

• Corporate Office Network: In a large office, different departments like HR, IT, and Finance might need separate networks to handle sensitive data. By creating VLANs for each department (e.g., VLAN 10 for HR, VLAN 20 for IT, VLAN 30 for Finance), the company can ensure data isolation, reduce traffic, and increase security within each department’s network.
• University Campus: Universities often use VLANs to separate traffic among faculty, students, and administrative departments. For example, VLAN 100 could be assigned to student networks, VLAN 200 to faculty, and VLAN 300 to administration. This segmentation helps manage network resources and secure sensitive data, such as administrative records, from unauthorised access.
• Guest and Employee Wi-Fi Networks: Many organisations set up separate VLANs for guest and employee Wi-Fi access. This way, employees’ network traffic can be kept on VLAN 1, with access to internal resources, while guests are placed on VLAN 2, where they have restricted access, limited to internet-only, for security purposes.

Terminologies in Computer Network:

General Terms:

• Network: A collection of interconnected devices (e.g., computers, printers, servers) that can communicate and share resources with each other.
• Node: Any device connected to a network, such as a computer, printer, router, or switch.
• Protocol: A set of rules and standards that define how devices on a network communicate and exchange information.
• IP Address: A unique numerical identifier assigned to each device on a network, enabling identification and communication with other devices.
• Router: A networking device that connects multiple networks together and forwards data packets between them, often directing traffic within and outside of local networks.
• Switch: A networking device that connects multiple devices within a single network and forwards data packets based on MAC addresses, enhancing communication efficiency.
• Firewall: A security device or software that monitors and controls incoming and outgoing network traffic based on predefined security rules to protect against unauthorised access.
• DNS (Domain Name System): A system that translates human-readable domain names (like www.example.com) into IP addresses, allowing devices to locate and connect to websites and other network resources.

Network Types:

• Internetwork: A general term for multiple networks connected together, with the Internet being the largest and most well-known example.
• SAN (Storage Area Network): A specialised network designed to provide high-speed, lossless access to large-capacity storage devices, often used in data centres.
• VPN (Virtual Private Network): A secure network that allows users to send and receive data across public or unsecured networks, enabling remote access to private networks while protecting data privacy.

Addressing and Communication:

• DHCP (Dynamic Host Configuration Protocol): A protocol that automatically assigns IP addresses and network configuration settings to devices on a network, simplifying network administration.
• TCP/IP (Transmission Control Protocol/Internet Protocol): A set of communication protocols used for transmitting data over the Internet and other networks, forming the basis of Internet communication.

Basic Protocols:

• IP (Internet Protocol): A protocol for sending data packets across networks, defining addressing methods for computers and devices.
• FTP (File Transfer Protocol): A standard network protocol used to transfer files between a client and a server on a computer network.
• SMTP (Simple Mail Transfer Protocol): A protocol used for sending and receiving email messages over the Internet.
• HTTP (Hypertext Transfer Protocol): The foundation of data communication on the World Wide Web, used for transferring web pages and other resources.

Roles in Networking:

• Client: A host that requests information or services from another host (the server).
• Server: A host that provides information, resources, or services to clients on the network.
• Peer: A host that can act both as a client and a server, requesting and providing information to other hosts in a network.

Miscellaneous Terms:

• Bandwidth: The maximum rate of data transfer across a network, often measured in bits per second (bps), determining the speed of data transmission.
• Latency: The time delay between the transmission of data and its receipt, affecting the responsiveness of network communication.
• Topology: The arrangement or layout of a network, describing how devices are interconnected. Common topologies include star, ring, bus, and mesh.
• Throughput: The actual amount of data successfully transmitted over a network in a given time frame, often affected by network conditions and congestion.

Topologies:

1. Bus Topology:

• The bus topology is designed in such a way that all the stations are connected through a single cable known as a backbone cable.
• Each node is either connected to the backbone cable by drop cable or directly connected to the backbone cable.
• When a node wants to send a message over the network, it puts a message over the network. All the stations available in the network will receive the message whether it has been addressed or not.
• The bus topology is mainly used in 802.3 (ethernet) and 802.4 standard networks.
• The configuration of a bus topology is quite simpler as compared to other topologies.
• The backbone cable is considered as a "single lane" through which the message is broadcast to all the stations.
• The most common access method of the bus topologies is CSMA (Carrier Sense Multiple Access).

Advantages of Bus topology:

• Low-cost cable: In bus topology, nodes are directly connected to the cable without passing through a hub. Therefore, the initial cost of installation is low.
• Moderate data speeds: Coaxial or twisted pair cables are mainly used in bus-based networks that support 10 Mbps.
• Familiar technology: Bus topology is a familiar technology as the installation and troubleshooting techniques are well known, and hardware components are easily available.
• Limited failure: A failure in one node will not have any effect on other nodes.

Disadvantages of Bus topology:

• Extensive cabling: A bus topology is quite simple, but still it requires a lot of cabling.
• Difficult troubleshooting: It requires specialised test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes.
• Signal interference: If two nodes send the messages simultaneously, then the signals of both the nodes collide with each other.
• Reconfiguration is difficult: Adding new devices to the network would slow down the network.
• Attenuation: Attenuation is a loss of signal that leads to communication issues. Repeaters are used to regenerate the signal.

2. Ring Topology:

• Ring topology is like a bus topology, but with connected ends.
• The node that receives the message from the previous computer will retransmit to the next node.
• The data flows in one direction, i.e., it is unidirectional.
• The data flows in a single loop continuously known as an endless loop.
• It has no terminated ends, i.e., each node is connected to another node and has no termination point.
• The data in a ring topology flow in a clockwise direction.
• The most common access method of the ring topology is token passing.

1. Token passing: It is a network access method in which a token is passed from one node to another node.

2. Token: It is a frame that circulates around the network.

Advantages of Ring topology:

• Network Management: Faulty devices can be removed from the network without bringing the network down.
• Product availability: Many hardware and software tools for network operation and monitoring are available.
• Cost: Twisted pair cabling is inexpensive and easily available. Therefore, the installation cost is very low.
• Reliable: It is a more reliable network because the communication system is not dependent on the single host computer.

Disadvantages of Ring topology:

• Difficult troubleshooting: It requires specialised test equipment to determine the cable faults. If any fault occurs in the cable, then it would disrupt the communication for all the nodes.
• Failure: The breakdown in one station leads to the failure of the overall network.
• Reconfiguration is difficult: Adding new devices to the network would slow down the network.
• Delay: Communication delay is directly proportional to the number of nodes. Adding new devices increases the communication delay.

3) Star Topology:

• Star topology is an arrangement of the network in which every node is connected to the central hub, switch or a central computer.
• The central computer is known as a server, and the peripheral devices attached to the server are known as clients.
• Coaxial cable or RJ-45 cables are used to connect the computers.
• Hubs or Switches are mainly used as connection devices in a physical star topology.
• Star topology is the most popular topology in network implementation.

Advantages of Star topology

• Efficient troubleshooting: Troubleshooting is quite efficient in a star topology as compared to bus topology. In a bus topology, the manager has to inspect the kilometres of cable. In a star topology, all the stations are connected to the centralised network. Therefore, the network administrator has to go to the single station to troubleshoot the problem.
• Network control: Complex network control features can be easily implemented in the star topology. Any changes made in the star topology are automatically accommodated.
• Limited failure: As each station is connected to the central hub with its own cable, therefore failure in one cable will not affect the entire network.
• Familiar technology: Star topology is a familiar technology as its tools are cost-effective.
• Easily expandable: It is easily expandable as new stations can be added to the open ports on the hub.
• Cost effective: Star topology networks are cost-effective as it uses inexpensive coaxial cable.
• High data speeds: It supports a bandwidth of approx 100Mbps. Ethernet 100BaseT is one of the most popular Star topology networks.

Disadvantages of Star topology

• A Central point of failure: If the central hub or switch goes down, then all the connected nodes will not be able to communicate with each other.
• Cable: Sometimes cable routing becomes difficult when a significant amount of routing is required.

4) Tree topology:

• Tree topology combines the characteristics of bus topology and star topology.
• A tree topology is a type of structure in which all the computers are connected with each other in hierarchical fashion.
• The top-most node in tree topology is known as a root node, and all other nodes are the descendants of the root node.
• There is only one path between two nodes for the data transmission. Thus, it forms a parent-child hierarchy.

Advantages of Tree topology

• Support for broadband transmission: Tree topology is mainly used to provide broadband transmission, i.e., signals are sent over long distances without being attenuated.
• Easily expandable: We can add the new device to the existing network. Therefore, we can say that tree topology is easily expandable.
• Easily manageable: In tree topology, the whole network is divided into segments known as star networks which can be easily managed and maintained.
• Error detection: Error detection and error correction are very easy in a tree topology.
• Limited failure: The breakdown in one station does not affect the entire network.
• Point-to-point wiring: It has point-to-point wiring for individual segments.

Disadvantages of Tree topology

• Difficult troubleshooting: If any fault occurs in the node, then it becomes difficult to troubleshoot the problem.
• High cost: Devices required for broadband transmission are very costly.
• Failure: A tree topology mainly relies on the main bus cable and failure in the main bus cable will damage the overall network.
• Reconfiguration difficult: If new devices are added, then it becomes difficult to reconfigure.

5) Mesh topology

• Mesh technology is an arrangement of the network in which computers are interconnected with each other through various redundant connections.
• There are multiple paths from one computer to another computer.
• It does not contain the switch, hub or any central computer which acts as a central point of communication.
• The Internet is an example of the mesh topology.
• Mesh topology is mainly used for WAN implementations where communication failures are a critical concern.
• Mesh topology is mainly used for wireless networks.
• Mesh topology can be formed by using the formula:Number of cables = (n*(n-1))/2;

Where n is the number of nodes that represents the network.

Mesh topology is divided into two categories:

• Fully connected mesh topology
• Partially connected mesh topology

• Full Mesh Topology: In a full mesh topology, each computer is connected to all the computers available in the network.
• Partial Mesh Topology: In a partial mesh topology, not all but certain computers are connected to those computers with which they communicate frequently.

Advantages of Mesh topology:

1. Reliable: The mesh topology networks are very reliable as if any link breakdown will not affect the communication between connected computers.

2. Fast Communication: Communication is very fast between the nodes.

3. Easier Reconfiguration: Adding new devices would not disrupt the communication between other devices.

Disadvantages of Mesh topology:

• Cost: A mesh topology contains a large number of connected devices such as a router and more transmission media than other topologies.
• Management: Mesh topology networks are very large and very difficult to maintain and manage. If the network is not monitored carefully, then the communication link failure goes undetected.
• Efficiency: In this topology, redundant connections are high that reduces the efficiency of the network.

6) Hybrid Topology:

• The combination of various different topologies is known as Hybrid topology.
• A Hybrid topology is a connection between different links and nodes to transfer the data.
• When two or more different topologies are combined together it is termed as Hybrid topology and if similar topologies are connected with each other will not result in Hybrid topology. For example, if there exists a ring topology in one branch of ICICI bank and bus topology in another branch of ICICI bank, connecting these two topologies will result in Hybrid topology.

Advantages of Hybrid Topology:

• Reliable: If a fault occurs in any part of the network will not affect the functioning of the rest of the network.
• Scalable: Size of the network can be easily expanded by adding new devices without affecting the functionality of the existing network.
• Flexible: This topology is very flexible as it can be designed according to the requirements of the organisation.
• Effective: Hybrid topology is very effective as it can be designed in such a way that the strength of the network is maximised and weakness of the network is minimised.

Disadvantages of Hybrid topology:

• Complex design: The major drawback of the Hybrid topology is the design of the Hybrid network. It is very difficult to design the architecture of the Hybrid network.
• Costly Hub: The Hubs used in the Hybrid topology are very expensive as these hubs are different from usual Hubs used in other topologies.
• Costly infrastructure: The infrastructure cost is very high as a hybrid network requires a lot of cabling, network devices, etc.