Saturday, February 25, 2023

What is a networking

Computer Networking DTechVNS

📡 Computer Networks - Complete Guide

What is a Computer Network?

A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies, based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies.

Key Components:

  • Nodes: Personal computers, servers, networking hardware
  • Network Addresses: Used for locating and identifying nodes
  • Hostnames: Memorable labels for nodes
  • Protocols: Rules for communication (like Internet Protocol)

Network Classification

Classification Basis Types Description
Transmission Medium Wired, Wireless Physical connection type
Geographic Scale PAN, LAN, MAN, WAN Coverage area
Topology Bus, Star, Ring, Mesh Physical layout
Organizational Scope Intranet, Extranet, Internet Access and control

Historical Timeline

1958

First Commercial Modem

Bell 101 modem released by AT&T Corporation - first commercial modem for computers (110 bits/sec)

1969

ARPANET Born

First four nodes connected between UCLA, Stanford, UCSB, and University of Utah (50 kbit/s circuits)

1973

Ethernet Invented

Robert Metcalfe invented Ethernet at Xerox PARC

1995

Fast Ethernet

Ethernet speed increased from 10 Mbit/s to 100 Mbit/s

1998

Gigabit Ethernet

Ethernet supported 1 Gbit/s transmission speed

Network Components & Devices

Network Interface Card (NIC)

Hardware that connects computer to network media

MAC Address: 6 octets

Repeaters & Hubs

Regenerate and distribute network signals

Layer: Physical (OSI)

Switches & Bridges

Forward frames based on MAC addresses

Layer: Data Link (OSI)

Routers

Forward packets between networks using routing tables

Function: Internetworking

Firewalls

Control network security and access rules

Purpose: Security

Modems

Convert digital to analog signals for transmission

Types: DSL, Cable, Dial-up

Transmission Media

Wired Media

  • Coaxial Cable: 200-500 Mbit/s (TV systems, offices)
  • Twisted Pair: 2 Mbit/s - 10 Gbit/s (Ethernet)
  • Optical Fiber: Up to trillions bits/sec (long distance)
  • Types: Single-mode & Multi-mode

Wireless Media

  • Terrestrial Microwave: Line-of-sight, low GHz range
  • Satellite: Geosynchronous orbit, global coverage
  • Cellular: Radio communication, geographic areas
  • Wi-Fi: IEEE 802.11, spread spectrum
  • Free-space Optical: Visible/invisible light, line-of-sight

Network Protocols

TCP/IP Protocol Suite

  • IP: Internet Protocol (addressing)
  • TCP: Transmission Control Protocol (reliable)
  • UDP: User Datagram Protocol (unreliable)
  • HTTP: HyperText Transfer Protocol (web)
  • FTP: File Transfer Protocol

IEEE 802 Standards

  • 802.3: Ethernet (wired LAN)
  • 802.11: Wireless LAN (Wi-Fi)
  • 802.1Q: VLAN (Virtual LAN)
  • 802.1X: Port-based Network Access Control

Other Protocols

  • SONET/SDH: Optical fiber multiplexing
  • ATM: Asynchronous Transfer Mode
  • DNS: Domain Name System
  • DHCP: Dynamic Host Configuration Protocol

Network Types by Geographic Scale

PAN Personal Area Network

Range: Up to 10 meters

Examples: Bluetooth, USB connections

LAN Local Area Network

Range: Building/campus

Speed: Up to 100 Gbit/s

Examples: Ethernet, Wi-Fi

MAN Metropolitan Area Network

Range: City/metro area

Technology: Fiber optics, microwave

WAN Wide Area Network

Range: Country/continents

Examples: Internet, enterprise networks

VPN Virtual Private Network

Purpose: Secure remote access

Technology: Tunneling, encryption

Network Performance Metrics

Bandwidth

Maximum data transfer rate (bit/s)

Measured in: bps, Kbps, Mbps, Gbps

Latency (Delay)

Time for data to travel across network

Types: Processing, Queuing, Transmission, Propagation

Throughput

Actual data transfer rate achieved

Always ≤ Bandwidth

Jitter

Variation in packet delay

Critical for real-time applications

Packet Loss

Percentage of packets lost

Causes: Congestion, errors

QoS

Quality of Service

Prioritization of traffic

Network Security

Authentication

Verifying user identity (IDs, passwords, biometrics)

Encryption

Protecting data confidentiality

  • SSL/TLS: Web security (HTTPS)
  • E2EE: End-to-End Encryption
  • VPN: Virtual Private Networks

Firewalls

Filtering unauthorized access

Types: Packet-filtering, Stateful, Application-level

Threats

  • Viruses & Worms
  • DDoS Attacks
  • Phishing
  • Man-in-the-Middle

Quick Reference

OSI Model Layers

  1. Physical
  2. Data Link
  3. Network
  4. Transport
  5. Session
  6. Presentation
  7. Application

Common Ports

  • HTTP: Port 80
  • HTTPS: Port 443
  • FTP: Port 21
  • SSH: Port 22
  • DNS: Port 53
  • SMTP: Port 25

Ethernet Speeds

  • Ethernet: 10 Mbps
  • Fast Ethernet: 100 Mbps
  • Gigabit: 1 Gbps
  • 10 Gigabit: 10 Gbps
  • 100 Gigabit: 100 Gbps
  • 400 Gigabit: 400 Gbps