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What is the Internet?
- Billions of connected devices:
- hosts = end systems
- running network apps at Internet’s “edge”
- Packet switches: forward packets (chunks of data)
- Communication links
- fiber, copper, radio, satellite
- transmission rate: bandwidth
- Networks
- collection of devices, routers, links: managed by an organization
- Internet: “network of networks”
- Interconnected ISPs (Internet Service Providers)
- protools are everywhere
- control sending, receiving of messages
- e.g., HTTP (Web), streaming video, SKype, TCP, IP, WiFi, 4G, Ethernet
- Internet standards
- RFC: Request for Comments
- IETF: Internet Engineering Task Force
- Infrastructure that provides services to applications:
- Web, streaming video, multimedia teleconferencing, email, games, e-commerce, social media, interconnected appliances, …
- provides programming interface to distributed applications:
- “hooks” allowing sending/receiving apps to “connect” to, use Internet transport service
- provides service options, analogous to postal service
What is a protocol?
- Network protocols:
- computers (devices) rather than humans
- all communication activity in Internet governed by protocols
- Protocols define the format, order of messages sent and received among network entities, and actions taken on message transmission, receipt