IPv4 Addressing and Network Switching

This page delves into the technical aspects of internet addressing and data transmission methods, focusing on IPv4 addressing and the concepts of circuit and packet switching.

Vocabulary: IPv4 $Internet Protocol version 4$ addresses are unique identifiers assigned to devices on a network, consisting of four 8-bit numbers $0-255$ separated by dots.

Example: An IPv4 address might look like this: 72.129.214.32

It's worth noting that newer IPv6 addresses use 128-bit numbers represented in hexadecimal format to accommodate the growing number of internet-connected devices.

Circuit Switching vs. Packet Switching

1. Circuit Switching: Used in traditional telephone networks Establishes a dedicated connection for the duration of a call Not suitable for internet data transmission due to limited capacity
2. Packet Switching: The method used for data transmission over the internet Breaks files into smaller data packets $typically 512 bytes each$ Each packet contains a header with crucial information

Definition: Packet switching is a method of data transmission where files are broken into smaller packets, each containing routing and sequencing information, allowing for efficient network utilization.

Packet headers include:

• Destination IP address
• Source IP address
• Sequence number
• Total number of packets in the communication
• Error checking data

Highlight: Packet switching allows data to flow through different routes on the internet, optimizing network resources and improving efficiency.

The recipient computer reassembles the packets upon arrival, checking for errors and requesting retransmission of corrupt packets if necessary. This method ensures reliable and efficient data transmission across the complex network infrastructure of the internet.

Network Infrastructure and Domain Name System

This page explores the fundamental components of network infrastructure and the Domain Name System $DNS$, which are crucial for the functioning of the internet.

Network Nodes and Routers

Vocabulary: Nodes are points on a network diagram, with routers being specialized nodes that direct data packets from one location to another.

Domain Name System $DNS$

The DNS is a hierarchical naming system for computers, services, or other resources connected to the internet. It translates human-readable domain names into IP addresses.

Example: The domain name "google.co.uk" corresponds to a specific IP address.

DNS Servers:

• 13 root DNS servers worldwide maintain a complete database of domain names and IP addresses
• Lower-level DNS servers, often owned by Internet Service Providers $ISPs$, hold partial databases
• Requests are passed between servers until a match is found

Highlight: The DNS allows users to access websites using easy-to-remember names instead of numerical IP addresses, greatly enhancing the user experience of the internet.

Dynamic IP Addresses

Home devices typically use dynamic IP addresses, which can change when:

• The router reconnects to the internet
• A device is used in a different location $e.g., on holiday$

Network Interface Cards $NICs$

NICs are essential hardware components in networked devices:

• Built into every networked device
• Can be wireless $with an antenna$ or wired $with a network cable socket$
• Often integrated into the motherboard of modern devices

Definition: A Network Interface Card $NIC$ is a hardware component that enables a device to connect to a network, facilitating the sending and receiving of data.

Understanding these components and systems is crucial for comprehending how data is transmitted and accessed across the global internet infrastructure.

MAC Addressing and Network Communication

This page focuses on Media Access Control $MAC$ addressing, a crucial aspect of network communication at the hardware level.

Definition: A Media Access Control $MAC$ address is a unique identifier assigned to network interface controllers $NICs$ for use as a network address in communications within a network segment.

Key points about MAC addresses:

1. Assigned by the manufacturer to each NIC
2. Devices may have multiple MAC addresses $e.g., for Ethernet and Wi-Fi$
3. Format example: 3B:14:E6:39:0A:20
4. There are 2^48 possible MAC addresses, enough for about 40,000 per person globally

Highlight: Unlike IP addresses, which can change, the MAC address of a NIC is unique and permanent.

Role of MAC Addresses in Network Communication

When you request a web page:

1. Each router along the data path uses the MAC address of the next router to forward the data packet
2. This process continues until the packet reaches its final destination

Example: A smartphone typically has two different MAC addresses: one for Wi-Fi and one for Bluetooth.

Understanding MAC addressing is crucial for network professionals as it plays a fundamental role in local network communications and helps in troubleshooting network issues.

Vocabulary: Network Interface Controller $NIC$ - A hardware component that connects a device to a network, often integrated into the device's motherboard in modern systems.

The use of MAC addresses in conjunction with IP addresses enables efficient and accurate data transmission across both local and wide area networks, forming the backbone of internet communication protocols.

Networks and Internet

The internet is a complex system of interconnected networks that supports various services and technologies. This page introduces key concepts related to internet infrastructure and its evolution.

Definition: The internet is a collection of interconnected networks that enables services such as the web, email, and file sharing.

Vocabulary: The World Wide Web $WWW$ is an information system of interlinked web pages and resources accessible through web browsers, utilizing HTTP for data transmission.

Wide Area Networks $WAN$ play a crucial role in the internet's structure. WANs connect remote locations using various technologies:

• Cables
• Telephone lines
• Satellites
• Radio waves

Highlight: The internet is considered the largest WAN in the world, connecting numerous organizational networks across geographical locations.

The growth of the internet has been remarkable:

• 1969: Four interconnected networks
• 1989: 100,000 connected networks
• 2019: 4.5 billion internet users

Example: The Internet of Things $IoT$ has contributed significantly to this growth. By 2020, over 31 billion IoT devices were connected to the internet, including mobile devices, parking meters, smart meters, cars, kitchen appliances, and even cat trackers.

Definition: The Internet of Things $IoT$ refers to the network of "smart" devices connected over the internet, allowing them to collect and exchange data.

This exponential growth in connectivity has transformed how we interact with technology and each other, paving the way for innovative applications and services across various sectors.