COMPUTER NETWORKING FOR CCNA BEGINERESS PART-2

COMPUTER NETWORKING FOR CCNA BEGINNERS

TWO TYPES OF TECHNOLOGIES USED IN NETWORKING

• -WIRED

• -WIRELESS

Examples Of Wired Technologies

Cable television systems, workplaces, and other locations where local area networks are used are frequently equipped with coaxial cable. Between 200 million bits per second and more than 500 million bits per second are transmitted.

To construct a high-speed local area network, ITU-T G.hn technology takes advantage of the coaxial cable, phone, and power lines that already exist in homes.

Standard wired Ethernet and other protocols use twisted pair cabling. 4 pairs of copper wiring, which can be used for both voice and data transmission, make up the standard configuration. Crosstalk and electromagnetic induction are diminished by using two wires that have been twisted together. 2 Mbit/s to 10 Gbit/s are the available transmission speeds. Unshielded and shielded twisted pairs (UTP and STP, respectively) are the two variations of twisted pair cabling. There are multiple category ratings for each form, each of which is intended for use in a different situation.

Glass fiber is an optical fiber. Through the use of lasers and optical amplifiers, it transmits light pulses that stand in for data. Optical fibers have a very low transmission loss and are immune to electrical interference, which are some benefits over metal cables. Using dense wave division multiplexing, optical fibers may send data at up to billions of bits per second by concurrently transmitting numerous streams of information on various light wavelengths. Optic fibers are utilized in undersea communication cables that connect continents and can be used for lengthy cable runs carrying extremely high data rates. A single-mode optical fiber (SMF) and multi-mode optical fiber (MMF) are the two fundamental varieties of fiber optics. The benefit of using single-mode fiber is that it can maintain a coherent signal for dozens or even 100 km. Depending on the data rate and cable grade, multimode fiber can only be extended for a few hundred or perhaps a few dozen of meters, making it more expensive to terminate.

Wireless

Computers are very often connected to networks using wireless links

Network connections can be established wirelessly using radio or other electromagnetic means of communication.

Terrestrial microwave — Terrestrial microwave communication makes use of satellite-dish-like transmitters and receivers that are situated on Earth. All communications are restricted to line-of-sight because terrestrial microwaves operate in the low gigahertz band. There are roughly 40 miles (64 km) between relay stations.

Satellites that carry out communication also use microwaves. In a geosynchronous orbit 35,400 kilometers (22,000 miles) above the equator, the satellites are fixed in space. These Earth-orbiting devices are equipped to receive and transmit TV, data, and voice signals.

The radio communications technology used by cellular networks is diverse. The systems separate the covered region into several different geographic regions. A low-power transceiver provides service to each location.

Technologies involving radio and spread spectrum - Wireless LANs use high-frequency radio technology akin to digital cellular. To allow communication between numerous devices in a constrained space, wireless LANs use spread spectrum technology. Wi-Fi is an open-standards wireless radio-wave technology that is commonly used. IEEE 802.11 defines Wi-Fi.

Visible or invisible light is used in free-space optical communication to carry messages. The majority of the time, line-of-sight propagation is employed, which places restrictions on the actual placement of communication devices.

The Interplanetary Internet IP via Avian Carriers was a lighthearted Request for Comments that was published as RFC 1149, extending the Internet to extraterrestrial dimensions using radio waves and optical techniques. In 2001, it was put into practice in real life. 

The last two cases have a large round-trip delay time, which gives slow two-way communication but doesn't prevent sending large amounts of information (they can have high throughput). 

Network nodes (node networking)

Apart from any physical transmission media, networks are built from additional basic system building blocks, such as network interface controllers, repeaters, hubs, bridges, switches, routers, modems, and firewalls. Any particular piece of equipment will frequently contain multiple building blocks and so may perform multiple functions.

Network interfaces

An ATM network interface in the form of an accessory card. A lot of network interfaces are built-in.

A network interface controller (NIC) is a piece of hardware for computers that links them to network media and can process basic network data. The NIC, for instance, might comprise circuitry and a connector for receiving a cable or an antenna for wireless transmission and reception. 

Each NIC in Ethernet networks has its own Media Access Control (MAC) address, which is often kept in the controller's permanent memory. The Institute of Electrical and Electronics Engineers (IEEE) upholds and regulates MAC address uniqueness to prevent address conflicts between network devices. Ethernet MAC addresses have a six-octet size limit. To identify NIC manufacturers, the three most important octets are set aside. Every Ethernet interface made by these manufacturers has its three least-significant octets assigned in a unique way utilizing just the prefixes that have been given to them. 

Repeaters and hubs

A repeater is a piece of technology that accepts network signals, removes any extraneous noise, and then regenerates the signals. For the signal to go further distances without degrading, it is retransmitted at a higher power level or to the other side of the obstruction. For cable runs longer than 100 meters, repeaters are usually needed in twisted-pair Ethernet systems. Repeaters can be tens of kilometers or even hundreds of kilometers apart when using fiber optics.

Repeaters recreate the signal quickly, although they still operate on the physical layer of the OSI model. This may damage the performance of the network and its ability to function properly by causing a propagation delay. As a result, many network topologies, such as the Ethernet 5-4-3 rule, have a cap on the number of repeaters that can be utilized in a network. 

The term "Ethernet hub" refers to an Ethernet repeater with several ports. A repeater hub helps the network with collision detection and fault isolation in addition to reconditioning and disseminating network signals. Modern network switches have rendered hubs and repeaters in LANs completely obsolete. 

Bridges and switches

In contrast to a hub, which forwards frames to all ports, network bridges and switches only send frames to the ports involved in the communication. The only ports seen on a bridge are two, but a switch can be viewed as a multi-port bridge. Switches typically have a large number of ports, allowing for device star topology and cascading further switches.

To create a single local network out of two or more network segments, bridges and switches operate at the data link layer (layer 2) of the OSI model. Both are devices that forward data frames across ports based on each frame's destination MAC address. By looking at the source addresses of incoming frames, they can determine how physical ports and MAC addresses are related, and they only forward frames when necessary. When attempting to communicate with an unidentified destination MAC, the device broadcasts the request to all ports other than the source and deduces the location from the response. 

Bridges and switches divide the network's collision domain but maintain a single broadcast domain. Network segmentation through bridging and switching helps break down a large, congested network into an aggregation of smaller, more efficient networks.

Bridges and switches separate the network's broadcast domain while keeping its collision domain intact. A large, crowded network can be divided into a collection of smaller, more effective networks using network segmentation techniques like bridging and switching.

Routers

A typical home or small office router shows the ADSL telephone line and Ethernet network cable connections

An internetworking device known as a router processes the addressing or routing information contained in a packet before forwarding it between networks. The routing table and the route information are frequently processed together. When deciding where to forward packets, a router consults its routing table rather than broadcasting them, which is inefficient in very large networks.

Modems

To connect network nodes using a wire that was not intended for wireless or digital network traffic, modems (modulator-demodulators) are utilized. To achieve this, the digital signal is modulated by one or more carrier signals to create an analog signal that can be adjusted to provide the necessary transmission-related features. Audio signals delivered over a traditional voice telephone connection were modulated by early modems. For telephone lines, cable television systems, and digital subscriber lines (DOCSIS), modems are still frequently utilized.

Firewalls

A firewall is a piece of network hardware or software that regulates access restrictions and network security. Connections between potentially insecure external networks, such as the Internet, and secure internal networks are protected by firewalls. Firewalls are often set up to allow actions from recognized sources while rejecting requests for access from unrecognized ones. Firewalls are becoming increasingly important for network security as cyberattacks continue to rise.

COMMUNICATION PROTOCOLS

Communication protocols are a set of rules and standards that determine how data is exchanged between different devices or systems. They provide a common language for different devices to communicate with each other and ensure that the data is transmitted and received correctly.

There are many different types of communication protocols, each designed for specific purposes and applications. Some common communication protocols include:

1)Transmission Control Protocol/Internet Protocol (TCP/IP): This is the most widely used communication protocol on the Internet. It provides reliable, connection-oriented data transmission between devices.

2)HyperText Transfer Protocol (HTTP): This is the protocol used for transferring data on the World Wide Web. It specifies how web browsers and servers should interact with each other.

3)File Transfer Protocol (FTP): This protocol is used for transferring files over a network. It allows users to upload and download files from remote servers.

4)Simple Mail Transfer Protocol (SMTP): This is the protocol used for sending and receiving email messages.

5)Hypertext Markup Language (HTML): This is a markup language used for creating web pages. It defines the structure and content of web pages.

6)Secure Sockets Layer/Transport Layer Security (SSL/TLS): These protocols are used for secure data transmission over a network. They provide encryption and authentication to ensure that data is transmitted securely.

Communication protocols are essential for the proper functioning of any network or system. They ensure that data is transmitted correctly and that devices can communicate with each other. Without communication protocols, devices would be unable to exchange data and networks would be unable to function.

GEOGRAPHICAL SCALE

Geographic scale refers to the spatial extent of a geographical phenomenon or process. It is a way of categorizing the size or scope of a phenomenon or process about its spatial context. There are several different scales of geography, each with its own characteristics and scope.

The most commonly recognized geographic scales include:

1)Local scale: This refers to phenomena that occur within a relatively small geographic area, such as a neighborhood or town.

2)Regional scale: This refers to phenomena that occur within a larger geographic area, such as a city, state, or province.

3)National scale: This refers to phenomena that occur within the boundaries of a nation-state, such as political or economic systems.

4)Global scale: This refers to phenomena that occur on a global level, such as climate change, international trade, or migration.

It's important to note that geographic scales are not mutually exclusive and that phenomena can occur at multiple scales simultaneously. For example, a political process may occur at both the national and regional scales, while a natural disaster may affect multiple geographic scales from the local to the global level.

Understanding the geographic scale of a phenomenon or process is important for developing effective policies and strategies, as the appropriate level of intervention will depend on the scale at which the phenomenon is occurring.

ORGANIZATIONAL SCOPE

In most cases, the companies who control a network administer it. Intranets and extranets may be combined in private enterprise networks. The Internet, which has no single owner and enables nearly infinite worldwide connectivity, may likewise be made available via their network.

INTERNET

An Internet is a private network that is used within an organization to facilitate communication, collaboration, and information sharing among its employees or members. It functions much like the public Internet, but it is accessible only to authorized users within the organization.

The main features of an intranet include:

1. Private network: An intranet is a closed network that is accessible only to employees or members of an organization.

2. Web-based interface: An intranet typically uses a web-based interface to allow users to access and share information.

3. Secure access: Access to an intranet is restricted to authorized users, and it typically requires a username and password to log in.

4. Centralized content management: An intranet is typically managed by a central team or department within the organization, which is responsible for managing the content and ensuring that it is up to date.

5. Collaboration tools: An intranet typically includes tools for collaboration and communication, such as email, instant messaging, and discussion forums.

6. Search functionality: An intranet typically includes a search function that allows users to quickly find the information they need.

Intranets are used by organizations of all sizes and types, from small businesses to large corporations and government agencies. They are particularly useful for organizations with multiple locations or remote workers, as they provide a centralized platform for communication and collaboration. Intranets can also help to improve productivity, reduce duplication of effort, and enhance the flow of information within an organization.

EXTRANET:-

An extranet is a private network that is used to provide secure and controlled access to specific external users, such as customers, partners, or suppliers. It is a secure extension of an organization's internal network that allows authorized external users to access certain information, applications, or services.

The main features of an extranet include:

1. Secure access: Access to an extranet is restricted to authorized external users, and it typically requires a username and password to log in. Access is usually granted only to specific areas of the extranet that are relevant to the external user's needs.

2. Web-based interface: An extranet typically uses a web-based interface to allow external users to access and share information.

3. Collaborative features: An extranet may include collaborative features such as email, instant messaging, discussion forums, and file sharing, which allow external users to communicate and work with internal staff.

4. Centralized content management: An extranet is typically managed by a central team or department within the organization, which is responsible for managing the content and ensuring that it is up to date.

5. Integration with internal systems: An extranet may be integrated with the organization's internal systems, such as customer relationship management (CRM) or enterprise resource planning (ERP) systems, to provide external users with access to relevant information.

Extranets are used by organizations to improve collaboration and communication with external stakeholders, such as customers, partners, and suppliers. They can be particularly useful in industries such as manufacturing, retail, and finance, where external stakeholders play a critical role in the organization's operations. Extranets help to streamline communication, reduce duplication of effort, and improve efficiency by providing external stakeholders with controlled access to the information and resources they need to do business with the organization.

INTERNET:-

The Internet is a vast network of linked computers and other electronic devices that communicate with one another using industry-standard protocols. It connects billions of people and objects all over the world and is the biggest and most used network in the world.

The main features of the Internet include:

1. Global reach: The Internet is a global network that connects people and devices from all over the world.

2. Standard communication protocols: The Internet uses a standard set of communication protocols, such as TCP/IP, HTTP, and SMTP, to ensure that devices can communicate with each other regardless of their hardware or software.

3. Open architecture: The Internet is built on an open architecture that allows anyone to create and publish content, applications, and services, and make them available to anyone else on the network.

4. Search functionality: The Internet includes a search function that allows users to find information on any topic quickly and easily.

5. Social networking: The Internet includes a variety of social networking platforms that allow users to connect and interact with each other online.

6. E-commerce: The Internet has become a major platform for e-commerce, allowing businesses to sell goods and services to customers all over the world.

7. Multimedia content: The Internet includes a vast array of multimedia content, including text, images, audio, and video, that can be accessed and shared by anyone with an Internet connection.

The way we interact, work, and conduct business has been completely transformed by the Internet. It has created new possibilities for innovation, creativity, and economic growth by enabling people and organizations to connect and work together on a global scale. The regulation of online material and behaviour, privacy, and security all face additional difficulties as a result.

Partial map of the Internet based on 2005 data. Each line is drawn between two nodes, representing two IP addresses. The length of the lines indicates the delay between those two nodes.

DARKNET:-

The Darknet, also known as the Dark Web, is a portion of the Internet that is not indexed by traditional search engines and can only be accessed using specialized software or configurations. It is a network that is intentionally hidden and difficult to access and is often associated with illegal activities.

The main features of the Darknet include:

1. Anonymity: The Darknet provides a high degree of anonymity, which makes it attractive to those who want to engage in illegal activities such as buying and selling drugs, weapons, or stolen data.

2. Encryption: The Darknet uses encryption to ensure that communication and transactions remain secure and private.

3. Specialized software: Accessing the Darknet requires specialized software, such as Tor (The Onion Router) or I2P (Invisible Internet Project), which enable users to browse the web anonymously and access hidden websites.

4. Hidden websites: The Darknet includes hidden websites that are not accessible through traditional search engines, and often require specific URLs or access codes to enter.

5. Illegal activities: The Darknet has gained notoriety for its association with illegal activities, such as the sale of drugs, weapons, and stolen data, as well as for hosting illegal marketplaces, forums, and communities.

It is important to note that while the Darknet has gained a reputation for being a haven for illegal activities, it also serves legitimate purposes, such as providing a safe and anonymous platform for journalists, activists, and whistleblowers to communicate and share information. However, because of the potential for illegal activities on the Darknet, it is important for users to exercise caution and be aware of the potential risks and consequences of their actions.

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