Networking Fundamentals

Networking Fundamentals

• Networking involves connecting devices to facilitate resource sharing and communication
• A host or end device is any computer on a network

Servers

• Servers are computers that furnish data to end devices
• Email servers, web servers, and file servers are examples of servers

Clients

• Clients request data from servers
• Examples include accessing a web page and sending an email

Peer-to-Peer Networks

• Devices can function as both client and server in peer-to-peer networks
• Suited for very small networks

Peer-to-Peer Advantages

• Easy to set up with less complexity and lower costs
• Useful for tasks like file transfer and printer sharing

Peer-to-Peer Disadvantages

• Lacks centralized administration and has security vulnerabilities
• Limited scalability and slower performance

Network Components

• Nodes are devices in a network like computers or smartphones
• Links are physical or wireless connections between nodes

Bandwidth and Latency

• Bandwidth refers to the maximum data amount transferred in a given time
• Latency is the delay in data transmission

Communication Protocols

• Protocols specify the rules for communication such as HTTP and FTP

Types of Networks

• Local Area Network (LAN) covers a small area
• Wide Area Network (WAN) covers a larger area like cities or countries; the internet is an example
• Metropolitan Area Network (MAN) covers a city

Wireless Networks

• Wireless networks use technologies like Wi-Fi, Bluetooth, and mobile networks

Common Network Types

• Small home networks connect a few computers to the internet
• Small office/home office networks allow a home or remote office computer to connect to a corporate network
• Medium to large networks encompass numerous locations with interconnected computers
• Worldwide networks connect hundreds of millions of computers globally, like the internet

Network Infrastructure Aspects

• Size of the area covered
• Number of users connected
• Number and types of services available
• Area of responsibility

Local Area Network (LAN)

• LANs are network infrastructures spanning a small geographical area
• Interconnect end devices in a limited area
• Administered by a single organization or individual

Wide Area Network (WAN)

• WANs are network infrastructures spanning a wide geographical area
• Interconnect LANs over a wide areas
• Administered by one or more providers
• Slower speed links compared to LANs

The Internet

• The internet comprises a global collection of interconnected LANs and WANs
• LANs connect to each other using WANs
• WANs may use copper, fiber optic cables, and wireless transmissions

Internet Governance

• No single entity owns the internet
• Organizations like IETF, ICANN, and IIAB help maintain its structure

Network Diagrams

• Network or topology diagrams use symbols to represent devices
• Terms include Network Interface Card (NIC), physical port, and interface
• "Port" and "interface" are interchangeably used

Physical vs. Logical Topologies

• Physical topology diagrams show the physical location of devices and cables
• Logical topology diagrams show devices, ports, and addressing schemes

Intranet and Extranet

• Intranets are private LAN and WAN collections within an organization accessible to authorized members
• Extranets provide secure network access to individuals from different organizations requiring data access

Network Communication

• End devices are where messages originate or are received
• Intermediary devices interconnect end devices (switches, routers, firewalls)

Intermediary Device Functions

• Intermediary devices regenerate and retransmit data signals
• Maintain information about network pathways
• Notify devices of errors

Network Media

• Communication flows through a medium, from origin to destination
• Metal wires in cables use electrical impulses
• Fiber optic cables use pulses of light
• Wireless uses modulation of electromagnetic wave frequencies

Network Protocols (TCP/IP)

• TCP/IP serves as the foundation of the internet
• HTTP/HTTPS are used for web communication
• SMTP/IMAP handle email communication
• DNS converts domain names to IP addresses

OSI Model

• The OSI Model is a theoretical framework standardizing network communication
• Developed by the International Organization for Standardization (ISO)
• Consists of seven layers, each with specific functions

Importance of OSI Model

• Standardization ensures interoperability of hardware and software
• Aids troubleshooting by isolating issues to specific layers
• Enables modular development by allowing developers to focus on layers

Physical Layer (Layer 1)

• The physical layer transmits raw bits (0s and 1s) over a physical medium
• Defines hardware specifications like cables, voltages, and frequencies
• Uses network cables, wireless signals, hubs, and repeaters

Data Link Layer (Layer 2)

• The data link layer organizes raw bits into frames for reliable transmission
• Uses MAC addresses for device identification and corrects frame-level errors
• Employs switches and network interface cards (NICs)

Network Layer (Layer 3) Functions

• Determines the best path for data transmission using IP addressing
• Handles packet forwarding and routing
• Includes routers and IP addresses (IPv4/IPv6)

Transport Layer (Layer 4)

• Ensures data transmission reliability
• Uses ports to identify applications and provides error checking

Transport Layer Components

• TCP (Transmission Control Protocol) provides reliable, connection-oriented but slower delivery
• UDP (User Datagram Protocol) enables fast but unreliable delivery

Session Layer (Layer 5)

• The sessions between devices are managed here
• Login/logout procedures are controlled
• Synchronizes data exchange

Session Layer Components

• Authentication (user logins, tokens)
• Checkpoints for long data transfers

Presentation Layer (Layer 6)

• Converts data into understandable format with encryption, compression, and encoding
• Includes data translation and SSL/TLS encryption

Application Layer (Layer 7)

• Provides interfaces and services for applications with protocols like HTTP, FTP, and SMTP
• Web browsers, email clients, and file transfer apps are key components

TCP/IP Model Facts

• TCP/IP was designed by Vint Cerf and Bob Kahn
• They are also called the fathers of the internet
• TCP/IP has Application, Transport, Network, and Link layers