Network Fundamentals presentation for grade 12 students.pptx

Networks

1. LAN, WAN, WLAN, PAN Different types of network

2. LAN (Local Area Network) A LAN is a network that connects computers and devices in a limited geographical area, such as a home, office, or school campus. LANs are typically owned, controlled, and managed by a single organization or individual. They usually use Ethernet cables or wireless technology like Wi-Fi to connect devices within the networ

3. WAN (Wide Area Network) A WAN is a network that spans a large geographical area, connecting multiple LANs and other networks together. WANs are often used to connect remote locations, such as branch offices or different cities. They rely on various communication technologies, including leased lines, satellites, and the Internet, to facilitate communication over long distances.

4. WLAN (Wireless Local Area Network) A WLAN is a type of LAN that uses wireless technology, such as Wi-Fi, to connect devices within a limited area. WLANs provide the same functionality as traditional wired LANs but offer the convenience of wireless connectivity, allowing users to connect to the network without the need for physical cables.

5. WLAN (Wireless Local Area Network)

6. PAN (Personal Area Network) A PAN is a network that connects devices within the immediate vicinity of an individual, typically within a range of a few meters. PANs are commonly used to connect personal devices, such as smartphones, tablets, laptops, and wearable technology, to each other and to other networks, such as LANs or the Internet. Bluetooth and infrared are examples of technologies used to create PANs.

7. SAN( Storage Area Network A SAN is a dedicated high-speed network that connects and consolidates storage resources to multiple servers. The primary purpose of a SAN is to provide block-level access to data storage. Unlike traditional storage architectures where storage devices are directly attached to servers, SANs separate storage resources from server resources, allowing multiple servers to access shared storage devices simultaneously.

8. Circuit Switching :  Connection-Oriented In circuit switching, a dedicated communication path or circuit is established between the sender and receiver for the entire duration of the communication. This path remains open, even if there is no data being transmitted. It’s a connection-oriented approach.   Fixed Bandwidth The allocated bandwidth is reserved for the entire duration of the call, regardless of whether data is actively being transmitted. This results in a constant, fixed data rate. Circuit switching is efficient for continuous data streams, such as voice and video, where a constant, dedicated connection is required. Examples Circuit switching is commonly associated with traditional telephone networks (PSTN – Public Switched Telephone Network). When you make a phone call, a circuit is established for the duration of the call.

9. Packet Switching In packet switching, data is divided into small packets that are individually transmitted across the network. Each packet can take its own path to the destination. Packet switching is connectionless, meaning there is no dedicated path for the entire communication. Variable Bandwidth Bandwidth is shared among multiple users and devices. The data rate is not fixed, and the available bandwidth is used more efficiently, as it is shared dynamically. Bursty Data Packet switching is efficient for bursty data, where data is sent in irregular intervals. It allows for efficient use of available bandwidth. Examples Packet switching is the basis for the Internet and most modern computer networks. It is highly versatile and can handle a wide range of data types, from text to multimedia content.

10. Segments, Packets & Frames

11. Segments Transport Layer (Layer 4 of the OSI model) Segmentation is the process of breaking down data from the higher layers (e.g., application layer) into smaller, manageable units for transmission. These smaller units are called segments. Segments contain sequence numbers and other control information.

12. Data Data TCP Segments Data Data Data

13. Packets Network Layer (Layer 3 of the OSI model) Packets are the data units used for communication between devices in a network. The network layer is responsible for routing packets from the source to the destination. Packets contain not only the data but also network layer IP addressing information . Each packet includes the source and destination IP addresses and other information for routing.

14. Data Data TCP Packets Data Data Data Data Data Data Data IP

15. Frames Data Link Layer (Layer 2 of the OSI model) Frames are the data units used for communication within a local network segment . The data link layer is responsible for controlling access to the physical medium (e.g., Ethernet or Wi-Fi) and ensuring reliable transmission within a local network. Each frame includes source and destination MAC addresses , frame delimiters, and error-checking information like CRC (Cyclic Redundancy Check)

16. Data Data TCP Frames Data Data Data Data Data Data Data IP Data MAC Data Data Data

17. Networks and the Internet

18. Hook If the World Wide Web is a web... What are at the joints? What are the fibres in between? Where does the web live??? How do we browse this web?

19. WWW and the Internet What is the difference between the World Wide Web and the Internet? The Internet, Born 1981, is a World Wide Network of interconnected LANs and WANs The World Wide Web is a distributed application that is contained within the Internet.

20. IPv4 - 32-Bit Numerical Addresses IPv4 is a 32 bit address split into 4 sections e.g. 255.255.255.255 Range 0 - 255 (256 Possibilities in each) Total addresses = 256 x 256 x 256 x 256 = 4.3 Billion. 4.2 Billion Addresses is not enough for the modern world as the world has 7 Billion plus inhabitants and many people have more than one internet connected device. Because of this we need to use Public / Private IP addressing and Dynamic IP / IP address pooling

21. IPv6 - 128-Bit Hexadecimal addresses 340,282,366,920,938,463,463,374,607,431,768,211,456 Addresses Eg: 134F:5B67:888A:4321:54B6:54FA:FFAA:5521 Advantages Future proof - plenty of unique addresses for each device. Security built in to the profile Allows for QOS packet prioritising. Disadvantages A bit more overhead in packet size Many legacy devices and systems still don't fully support IPv6 so we still need IPv4 backup. Impossible to memorise addresses?

22. Static NAT - Using multiple public IP Addresses Not explicitly on the syllabus...

23. Gateways

24. Servers and the Internet There are different types / functions of servers on the internet: File Server - stores and serves files Application Server - runs internet based applications Web Server - serves web pages Domain Name Server - Provides the Domain Name Service Proxy Server - Provides internet access via another computer These roles may be performed by a single machine or multiple machines

25. Server Ports

26. URLS An URL (aka web address) is the alpha-numerical address that humans type in to a web browser to access a website. Humans like to use URLs rather than IP Addresses because they are easy to remember. An URL can be the name of a website or a specific page and may also contain query parameters / port numbers. URLs contain: Protocol - Host Name:port number - File Name/Location - Reference/Arguments https:// learnlearn.uk:443 /alevelcs/ ?s=internet Only the protocol and host-name are required, rest are optional. If you don't add the protocol most browsers will default to https

27. Why do we need them? All data transmitted across the internet is sent and received using Internet Protocol (IP). Data is sent from computer to computer in packets , with each packet containing a source and destination IP Address . When people want to use the world wide web, they connected to websites by typing in a domain name (AKA Web Address), for example www.google.com . The computer needs to know the IP Address that corresponds to www.google.com , so that it can send the packet of data requesting Google send the webpage, so that it can be loaded on the user's internet browser.

28. Step 1 Your computer checks its DNS Cache to see if it has already cached the domain name & IP Address in its DNS Cache.

29. Step 2 Your computer sends a request to your ISP for the domain name IP Address. If it has the IP address it returns the address, otherwise we go to step 3.

30. Step 3 Your ISP contacts one of 13 global root servers. The root server returns the IP address of the Top Level Domain (TLD) Server. Top level domains are the .com, .uk, .co.uk etc at the end of a domain name

31. Step 4 Your ISP Contacts the TLD Server and the TLD returns the IP Address of the Name Serve r that knows the IP address of the learnlearn.uk server.

32. Step 5 Your ISP Contacts the name sever and the name server returns the IP Address of learnlearn.uk's server. Your ISP returns to your machine the IP Address and stores the learnlearn.uk address in its DNS Cache Table for a short amount of time(max 1 day usually).

33. Step 6 Your computer Caches the IP Address / Domain Name Combo and then finally sends the request for data to the learnlearn.uk's server. The learnlearn.uk's server serves the request, returning the HTML page ETC.

34. Exam Questions Why do we need to public and private IP addresses? How does NAT function? What is the difference between URLS and IP addresses What is the purpose of DNS? How does DNS work?

35. Intranet Intranets (mini private internets) An intranet is a private network that is only accessible to limited group of users, for instance the Employees of company or members of a scout group. They are used for : Sharing hardware resources ( such as printers, scanners, etc) Allowing users to access their files from multiple locations. File sharing within the company. Company-wide file backup Advantages of Intranets Files can be shared within a company that you don’t outsiders to see ( employee records, new product information) Intranet sites ( websites only available inside an intranet) often run faster than external sites. Expensive hardware like printers can be shared, so you don’t need a printer for each user. Technically difficult tasks such as automated backups can be performed by one person, who backs up everyone’s files

36. Extranet Extranets are a small portion of an intranet available externally to authorised users.

37. Virtual Private Networks

38. What is a VPN? A VPN, or Virtual Private Network, is a technology that creates a secure and encrypted connection over a less secure network, such as the internet. This allows users to send and receive data as if their devices were directly connected to a private network, offering privacy, security, and anonymity.

39. Consumer VPN Used for privacy, security and spoofing physical location. The user connects to the VPN proxy server via an encrypted connection . The VPN proxy server switches the IP address before forwarding the packet to the destination website, masking the user's real identity and location from the destination website.

40. Features of VPNs Encryption: VPNs encrypt data transmitted between your device and the VPN server, making it difficult for third parties to intercept or access your data. Anonymity: By masking your IP address, a VPN can make your online actions more anonymous, hiding your browsing activity from your internet service provider (ISP) and other entities. Access to Restricted Content: VPNs can allow users to bypass geo-restrictions and censorship by routing their connection through servers in different locations, enabling access to content that might be blocked in their region. Secure Connection: VPNs can protect data on public Wi-Fi networks, preventing potential security breaches when using such networks.

41. Multiple Exit Nodes Exit nodes, or exit servers, are the final VPN servers through which your internet traffic exits before reaching its destination. When a VPN offers multiple exit nodes, it allows your data to be routed through several different servers, often in various countries, before it reaches its final destination. This is sometimes referred to as multi-hop or double VP

42. Remote Access VPN Purpose Enables individual users to connect to a private network from a remote location. Use Case Commonly used by remote workers to securely access their company's internal network. How It Works Users connect to the VPN server through client software, creating an encrypted tunnel for data transmission.

43. Site to Site VPN Purpose Connects entire networks to each other, typically used by businesses with multiple office locations. Use Case A company with offices in different cities can use a site-to-site VPN to connect their networks, allowing employees at each site to access resources on the other network. How It Works Establishes a secure, encrypted connection between the routers of different networks.

44. VPN for IP Spoofing

45. VPN over public wifi

46. IPSec Modes IPsec (Internet Protocol Security) operates in two primary modes: Transport Mode and Tunnel Mode. Each mode serves different purposes and has distinct characteristics.

47. Transport Mode Transport Mode encrypts only the payload of the IP packet, leaving the original IP headers intact.It is typically used for end-to-end communication between hosts. Use Cases Host-to-host communication: Ideal for securing communication between two computers directly. Application-layer security: Useful when applications need to securely communicate without altering the underlying network infrastructure.

48. Tunnel Mode Tunnel Mode encrypts the entire IP packet, including both payload and headers, and then encapsulates it into a new IP packet with a new header.Commonly used for network-to-network (site-to-site) or network-to-host communication. Use Cases: VPNs: Frequently used to establish secure site-to-site or remote access VPNs. Gateway-to-gateway communication: Secures traffic between two network gateways, providing a secure tunnel over the internet or other untrusted networks.

49. How HTML web pages are served

50. How are pages loaded?

51. Step 1 The user enters the Unique Resource Locator (AKA web address) of the website/web-page to be loaded into a web browser. The browser looks in the computer's DNS cache to see if a matching IP address is stored. ** Not found → step 2 / Found → step 4 **

52. Step 2 A request is sent to the ISP's DNS resolver server to find out the IP address. The DNS resolver looks for the IP address and if it is stored the DNS Server returns the IP address to the originator. ** If not found → Step 3 ** catgifs.com? catgifs.com IP is 198.49.23.144 ISP Resolver Server

53. Step 3 The request is passed on to a higher level DNS. Once found the original DNS caches the IP address for future use and returns the IP address to the user. catgifs.com? catgifs.com IP is 198.49.23.144 ISP Resolver Server Root Server TLD Server Name Server

54. Step 4 The browser uses the IP address to send the web page request to the web server. Catgifs.com Server Get request: Home page

55. Step 5 The web server retrieves the page and sends it to the originator. Catgifs.com Server index.html

56. Step 6 The browser interprets the script and loads the page.

57. The user enters the URL of the website/web-page to be loaded into a web browser. The browser looks in the computer's DNS cache to see if a matching IP address is stored. ** If not found → step 2 / Found → step 4 ** A request is sent to the ISP's DNS resolver server to find out the IP address. The DNS resolver looks for the IP address and if it is stored the DNS Server returns the IP address to the originator. ** If not found → step 3 / Found → step 4 ** The request is passed on to a higher level DNS. Once found the original DNS caches the IP address for future use and returns the IP address to the user. The browser uses the IP address to send the web page request to the web server. The web server retrieves the page and sends it to the originator. The browser interprets the script and loads the page. How simple HTML web pages are served

58. Introduction to Protocols Protocols are a set of rules and conventions that govern the way data is formatted, transmitted, and received in computer networks and communication systems. These rules and conventions define how devices on a network should communicate with each other, ensuring that data is exchanged in a structured, consistent, and reliable manner. Protocols are essential for enabling interoperability and efficient communication within and between different devices and systems. Without protocols networking equipment from different manufacturers would not work together.

59. Key Aspects of Protocols Standardisation Protocols provide a standardized way for devices to communicate. This standardization ensures that different devices, from different manufacturers and running different operating systems, can work together seamlessly. Interoperability Protocols enable interoperability, allowing devices with varying capabilities and configurations to exchange data. This is crucial in heterogeneous network environments where multiple devices and technologies coexist. Error handling Protocols define how errors in data transmission are detected, reported, and corrected. This helps ensure data integrity and reliability during transmission.

60. Key Aspects of Protocols Flow control Many network protocols include mechanisms for flow control to manage the rate of data transmission and prevent congestion in the network. Security Protocols often include security features to protect data during transmission, such as encryption, authentication, and authorization mechanisms. Data formatting Protocols specify how data should be formatted before transmission, including how it should be structured, encoded, and encapsulated. This ensures that data is correctly understood by the recipient.

61. Common Network Protocols Transmission Control Protocol (TCP) A protocol responsible for reliable data transmission in the Internet Protocol (IP) suite. It ensures that data is delivered in the correct order and without errors. Internet Protocol (IP) A protocol for addressing and routing data packets across the Internet. Hypertext Transfer Protocol (HTTP) A protocol used for transmitting web pages and other resources over the World Wide Web. File Transfer Protocol (FTP) A protocol used for transferring files between computers over a network.

62. Common Network Protocols Simple Mail Transfer Protocol (SMTP) A protocol for sending and receiving email messages. Post Office Protocol (POP) and Internet Message Access Protocol (IMAP) Protocols for retrieving email from a mail server. Secure Sockets Layer (SSL) and Transport Layer Security (TLS) Protocols for encrypting data transmitted over the internet to ensure secure communication. `

63. Public IP Addresses Each LAN connected to the internet usually has a single public IP Address*. This is the address seen by other computers and networks on the Internet and is the address attached to packets sent across the Internet. There are 2 main types of Public IP Addresses:  Static  and  Dynamic * For larger organizations they might have a whole IP range issued to them instead, depending on what kind of network address translation (NAT) they are using. Publics addresses are usually assigned by your ISP.

64. Private IP Addresses Computers within a LAN have their own private IP Address, that is different to their Public IP Address. This private IP Adddress is either: Issued by the Server / Router using Dynamic Host Configuration Protocol (DHCP) Set manually by the computer user themselves. Private IP addresses are usually in the 192.168.x.x range though can also be in the 10.x.x.x and 172.x.x.x

65. Network Address Translation(NAT) When a user sends a packet from a computer to a server over the internet, the NAT server swaps the private IP address for a public IP Address and attaches a PORT ID to the packet. The NAT server keeps track of which computers are assigned to which private IP address, so that when a packet returned to the port, it can swap that public IP address on the packet back to the private ip address and send it through the LAN to the correct computer.

66. IPv4 IPv4 is a 32 bit address split into 4 sections e.g. 255.255.255.255 Range 0 – 255 (256 Possibilities in each) Total addresses = 256 x 256 x 256 x 256 = 4.3 Billion. 4.2 Billion Addresses is not enough for the modern world as the world has 7 Billion plus inhabitants and many people have more than one internet connected device.

67. IPv6 IPv6 is 128 Bit Address, 340,282,366,920,938,463,463,374,607,431,768,211,456 Addresses. Probably enough for the foreseeable future. Advantages Future proof – plenty of unique addresses for each device. Security built in to the profile Allows for QOS packet prioritising. Disadvantages A bit more overhead in packet size Many legacy devices and systems still don’t fully support IPv6 so we still need IPv4 backup.

68. learnlearn.uk / ibcs