types of computer networks:
Local Area Network (LAN):
- A LAN is a network that typically covers a small geographic area, such as a single building or campus.
- It connects computers and devices to share resources and data locally.
- Sharing Peripherals is an advantage of LAN.
- Examples: Office LANs, home networks.
- Token Ring is a network topology and access method used in local area networks (LANs). It was developed by IBM in the 1970s
- Token Ring networks are characterized by a logical ring topology, in which data travels in a unidirectional or bidirectional manner around a closed-loop network.
- LAN has the highest transmission speed.
- LANs have a high data transfer rate and faster speed than MAN and WAN.
- WLAN stands for “Wireless Local Area Network.”
- It is a type of computer network that uses wireless communication to connect devices within a limited geographic area, such as a home, office, campus, or public hotspot.
Wide Area Network (WAN):
- A WAN spans a larger geographical area, often connecting LANs or other networks across cities, countries, or continents.
- It uses public or private infrastructure for data transmission.
- It is also termed as long haul Networks.
- Examples: The Internet, corporate WANs connecting branch offices.
- The Internet is called a super network or meta Network.
Metropolitan Area Network (MAN):
- A MAN falls between LANs and WANs in terms of size and covers a metropolitan area like a city. It provides high-speed connectivity for organizations within the same city.
- Examples: Citywide Wi-Fi networks, cable TV networks.
Personal Area Network (PAN):
- A PAN is a small network designed for personal or device-to-device connections over short distances, often within a few meters.
- Examples: Bluetooth connections, wireless USB.
Campus Area Network (CAN):
- A CAN is larger than a LAN but smaller than a MAN. It typically connects multiple buildings within a university campus or business complex.
- Examples: University campus networks, corporate campus networks.
Virtual Private Network (VPN):
- A VPN is a secure network that uses encryption to create a private and secure connection over a public network, such as the Internet. It’s often used for remote access and secure data transmission.
- Examples: Corporate VPNs, remote work connections.
Intranet:
- An intranet is a private network based on internet technologies that is restricted to an organization.
- It provides internal services, information sharing, and collaboration tools.
- Examples: Company intranets, educational institution intranets.
Extranet:
- An extranet extends an intranet to include external parties, such as business partners, suppliers, or customers.
- It allows controlled access to certain resources.
- Examples: Supplier portals, customer access to order status.
Client-Server Network:
- In a client-server network, one or more servers provide services and resources to multiple client devices.
- Clients request and use resources from the servers.
- Examples: Web servers serving web pages, file servers for data storage.
Peer-to-Peer Network (P2P):
- In a P2P network, devices communicate directly with each other without a centralized server. Each device can act as both a client and a server.
- Examples: File-sharing networks, decentralized blockchain networks.
Internet of Things (IoT) Network:
- IoT networks connect a large number of physical devices, sensors, and objects to the internet, allowing them to exchange data and interact.
- Examples: Smart home networks, industrial IoT networks.
Industrial Control System (ICS) Network:
- ICS networks are used in industrial settings, such as manufacturing and utilities, to control and monitor processes and equipment.
- Examples: SCADA (Supervisory Control and Data Acquisition) networks.
Networking mode :
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- “Networking mode” typically refers to the operational mode or configuration used in computer networking, specifically in the context of wireless networking.
- It describes how devices within a network are set up to communicate with each other.
- Here are the two primary networking modes commonly used in wireless networking:
- Infrastructure Mode:
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- In this mode, devices communicate through a central wireless access point (AP) or router.
- The access point acts as a central hub that connects multiple wireless devices to the network and provides access to the internet if needed.
- Suitable for home networks, business networks, and public Wi-Fi hotspots.
- Provides a centralized point for network management and security configurations.
- Ad Hoc Mode (Peer-to-Peer Mode):
- Ad hoc mode, also known as peer-to-peer mode, allows wireless devices to connect directly to each other without the need for a central access point or router.
- In this mode, devices communicate in a decentralized manner.
- Often used for creating temporary networks for file sharing, collaborative work, or scenarios where infrastructure mode is not available.
- Devices in an ad hoc network need to be in close proximity to each other.
Components of Computer networks :
- Computer networks consist of various components and devices that work together to enable communication and data exchange between computers and other devices.
- These components are organized to form a network infrastructure.
Nodes (Devices):
- Nodes are the devices connected to the network.
- They can be computers, servers, laptops, smartphones, tablets, printers, and other devices that participate in network communication.
Network Interface Cards (NICs):
- NICs are hardware components that enable devices to connect to the network.
- They provide a physical or wireless interface for data transmission.
Switches:
- Switches are networking devices that operate at the data link layer (Layer 2) of the OSI model.
- They are used to connect multiple devices within a local network (LAN) and forward data frames to the appropriate destination based on MAC addresses.
Routers:
- Routers are networking layer devices that operate at the network layer (Layer 3) of the OSI model.
- They connect different networks together and make routing decisions to forward data between them.
- Routers are essential for connecting LANs to form a wide area network (WAN) or connecting a LAN to the internet.
Access Points (APs):
- Access points are used in wireless networks to allow devices to connect wirelessly. They provide wireless connectivity to a wired network and manage wireless client connections.
Modems:
- Modems (modulator-demodulator) are used to convert digital data from a computer into analog signals for transmission over analog communication lines (e.g phone lines) or to convert analog signals from these lines into digital data for computers.
repeater :
- A repeater in information technology (IT) and networking is a device that is used to extend the range and improve the quality of data transmission within a network.
- Repeaters are primarily used in wired and wireless networks to overcome signal degradation and loss that occurs over long distances or due to other factors.
- Signal Amplification: The primary function of a repeater is to amplify and regenerate signals.
- It is also known as Signal Booster.
Bridge :
- In information technology (IT) and networking, a bridge is a network device or component that operates at the data link layer (Layer 2) of the OSI model.
- Its primary function is to connect and filter traffic between two or more network segments, making decisions based on the hardware (MAC) addresses of devices.
- Bridges are used to divide a larger network into smaller segments or collision domains, which can help reduce network congestion and improve overall network performance.
Firewalls:
- Firewalls are security devices that control incoming and outgoing network traffic, enforcing security policies and protecting the network from unauthorized access and threats.
Gateways:
- Gateways are devices or software programs that translate data between different network protocols or formats.
- They enable communication between networks that use different technologies or standards.
Cabling and Connectors:
- Various types of cabling (e.g., Ethernet cables, fiber-optic cables) and connectors are used to physically connect devices within a network. The choice of cable and connector depends on the network type and requirements.
Network Operating System (NOS):
- NOS is software that manages and controls network resources. It provides features like file sharing, user authentication, and network management. Examples include Windows Server, Linux distributions, and Cisco IOS for routers.
Servers:
- Servers are computers or devices that provide specific services to network users. These services can include file storage, email, web hosting, and more.
Clients:
- Clients are devices, such as computers and smartphones, that request and use services provided by servers on the network.
Protocols:
- Protocols are rules and conventions that govern how data is transmitted and received over a network. Examples include TCP/IP, HTTP, and FTP.
Network Topology:
- Network topology refers to the physical or logical layout or arrangement of network components.
- Common topologies include star, bus, ring, and mesh.
Cabling Infrastructure:
- The physical cabling infrastructure consists of cables, connectors, and distribution hardware (e.g., patch panels, switches) that provide the physical medium for data transmission.
Power Supply and Backup:
- Reliable power supply and backup systems (e.g., uninterruptible power supplies or UPS) are crucial to ensure continuous network operation, especially in critical environments.
Others Terms :
Piggybacking on Network Connections:
- Piggybacking can also refer to the unauthorized use of someone else’s network connection, often without their knowledge or consent.
- Technique of Temporarily Delaying Outgoing Acknowledgements.
WEP stands for “Wired Equivalent Privacy,” and it is a security protocol used to protect wireless computer networks.
Network congestion occurs when a computer network experiences an excessive volume of data traffic that exceeds its capacity, leading to performance degradation, delays in data transmission, and potential packet loss. Network congestion can happen in both wired and wireless networks and can occur for various reasons.
Deadlock :
- Deadlock in the context of computer networks refers to a situation where two or more devices or processes are unable to proceed with their intended tasks because they are waiting for each other to release a resource or take a specific action.
- In a deadlock scenario, the involved entities become effectively stuck, and no progress can be made until the deadlock is resolved.
OSI (Open Systems Interconnection) model
- The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and standardize how different networking protocols and technologies interact in a networked environment.
- The OSI model consists of seven distinct layers, each responsible for specific functions and services in the network.
- Here are the seven layers of the OSI model, from the top (Layer 7) to the bottom (Layer 1):
Layer 7: Application Layer:
- The Application Layer is the topmost layer and is responsible for providing network services directly to end-users and applications.
- It handles tasks such as data encoding, encryption, and application-specific protocols.
- Examples of protocols at this layer include HTTP, FTP, SMTP, and DNS.
Layer 6: Presentation Layer:
- The Presentation Layer is responsible for data translation, encryption, and compression.
- It ensures that data is presented in a format that can be understood by both the sender and the receiver.
- Functions at this layer include character encoding (e.g., ASCII to Unicode conversion) and data encryption/decryption.
Layer 5: Session Layer:
- The Session Layer establishes, manages, and terminates communication sessions between two devices.
- It handles session synchronization, checkpointing, and recovery.
- Protocols at this layer manage dialog control and may include NetBIOS and RPC (Remote Procedure Call).
Layer 4: Transport Layer:
- The Transport Layer is responsible for end-to-end communication between devices.
- It provides error detection and correction, as well as flow control to ensure reliable data transmission.
- Key protocols at this layer include TCP (Transmission Control Protocol) for reliable communication and UDP (User Datagram Protocol) for connectionless, faster communication.
Layer 3: Network Layer:
- The Network Layer is responsible for logical addressing, routing, and forwarding data packets between devices across different networks.
- It uses logical addresses (e.g., IP addresses) to route data. Protocols such as IP (Internet Protocol) operate at this layer.
- Examples : IP, Routers
Layer 2: Data Link Layer:
- The Data Link Layer is responsible for framing data into packets, adding hardware addresses (e.g., MAC addresses), error detection, and managing access to the physical transmission medium.
- It ensures data is transmitted reliably within a local network segment.
- Protocols include Ethernet, Wi-Fi (802.11), and PPP (Point-to-Point Protocol).
Layer 1: Physical Layer:
- The Physical Layer deals with the physical transmission of data over the network medium, such as cables, fibers, or wireless signals.
- Examples include Ethernet cables, fiber optics, and wireless radio waves.
Network Topology
- Network topology refers to the physical or logical layout or arrangement of devices and connections within a computer network.
- It defines how devices such as computers, routers, switches, and other network equipment are interconnected and how data is transmitted between them.
- There are several common network topologies, each with its own characteristics:
Bus Topology:
- In a bus topology, all devices are connected to a single central cable, called the bus or backbone.
- Data is transmitted in both directions along the cable, and devices listen for data intended for them.
- It is simple to set up but may suffer from network congestion and is not suitable for large networks.
Star Topology:
- In a star topology, all devices are connected to a central hub or switch.
- Data traffic between devices passes through the hub or switch, which manages the connections.
- It offers better fault tolerance than bus topology because a failure of one device does not affect the others, but the hub or switch is a single point of failure.
- LAN is based on star topology.
Ring Topology:
- In a ring topology, devices are connected in a closed-loop, with each device connected to exactly two other devices.
- Data circulates around the ring in one direction, and each device passes data to its neighbor.
- It offers good fault tolerance, as data can still travel in the opposite direction if a device or connection fails, but it can be challenging to add or remove devices.
Mesh Topology:
- In a full mesh topology, every device is connected to every other device in the network.
- It provides the highest level of fault tolerance and redundancy but can be costly and complex to implement, especially in large networks.
- Partial mesh topologies connect some devices to all others, striking a balance between redundancy and cost.
Tree Topology (Hierarchical Topology):
- A tree topology combines characteristics of star and bus topologies.
- Devices are organized hierarchically, with lower-level devices connected to upper-level devices, forming a tree-like structure.
- It is commonly used in large networks such as organization-wide networks, where departments or branches are connected to a central core.
Hybrid Topology:
- Hybrid topologies combine two or more different topologies to meet specific network requirements.
- For example, a network might have a combination of a star topology within departments and a backbone ring topology connecting department hubs.
Point-to-Point Topology:
- Point-to-point topology is the simplest, where two devices are directly connected to each other.
- It is commonly used for direct communication between two devices, such as a computer and a printer or two routers.
Data transmission modes
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- Data transmission modes, also known as communication modes or transfer modes, define how data is transmitted between two devices or systems in a network or communication context.
- There are three primary data transmission modes:
- Simplex Mode:
- Half-Duplex Mode:
- Full-Duplex Mode:
Simplex Mode:
- In simplex mode, communication occurs in one direction only, from the sender to the receiver.
- The sender transmits data, and the receiver can only receive and read the data but cannot send a response.
- Examples of simplex communication include television and radio broadcasts, where the sender (broadcast station) transmits content to multiple receivers (TV or radio sets).
Half-Duplex Mode:
- Half-duplex mode allows communication in both directions, but not simultaneously.
- Devices can transmit and receive data, but they cannot do so at the same time. They take turns.
- Walkie-talkies and many two-way radios use half-duplex communication. Users press a button to talk and release it to listen.
Full-Duplex Mode:
- Full-duplex mode enables communication in both directions simultaneously.
- Devices can transmit and receive data concurrently without taking turns.
Ethernet networks, telephone conversations, and most modern data communication systems, including the internet, use full-duplex communication