What is Internet?

Infrastructure that provides services to networked (distributed) applications

• Web, email, games etc

Hardware

• Millions of connected computing devices
  • hosts = end systems
  • running network apps
• Communication Links
  • Fiver, copper, radio, satellite
• Packet switches
  • forward packets(chunks of data)
  • routers and switches

Software

• Protocols control sending, receiving of msgs
  • rules for communications
  • similar to languages in conversations
• Standards
  • Define protocols
  • Internet standards(TCP, IP, HTTP)
  • WiFi standards
  • Cellular standards

What’s a protocol

Protocols define format, order of msgs sent and received among network entities and action taken on msg transmission, receipt

Network

• Network edge
  • hosts (end systems) : clients and servers
  • access networks : physically connect end systems to the core (edge router)
• Network core
  • Interconnected routers
  • network of networks

Network edge

Hosts, access network, physical media

❓How to connect end systems to edge router?

• residential access networks
  • 집
• mobile access networks
  • 스마트폰-기지국
• institutional access networks
  • 학교, 회사

• Access net : cable network