Computer Communication Networks: Internet Intro

Introduction to Computer Networks

• A computer network comprises end-systems or hosts connected through communication links and packet switches.
• End-systems generate or receive data in packets, collections of bits.
• The sequence of packet switches and communication links is termed as a route or path.
• Administration of a computer network is usually handled by a single entity.

Internet Overview

• The Internet is a vast network interconnecting billions of computing devices worldwide.
• It provides services for distributed applications, which run across different hosts.
• Key historical developments include DARPA, ARPANET, packet switching, TCP/IP, and DNS.

Notable Inventions and Inventors

• World Wide Web: Tim Berners-Lee, MIT, 1989-90.
• Email: Ray Tomlinson, BBN, 1972.
• DNS: Paul Mockapetris, USC, 1982.
• RFC: Stephen Crocker, UCLA, 1969.
• Packet Switching: Leonard Kleinrock, UCLA, 1961.
• TCP/IP: Bob Kahn and Vincent Cerf, DARPA/SRI, 1972-73.
• Ethernet: Bob Metcalfe, Xerox PARC, 1973.

Internet Ownership and Control

• Internet access is provided by Internet Service Providers (ISPs), which charge subscription fees.
• End-systems connect to ISPs at points-of-presence (PoPs), with thousands of PoPs indicating ISP reach.
• PoPs include routers, link layer switches, and communication links.

ISP Hierarchy and Revenue Generation

• End users pay access ISPs, which then pay regional ISPs, leading to Tier 1 ISPs.
• Tier 1 ISPs can have bilateral agreements to share bandwidth and resources.
• Peering or multi-homing ISPs may share revenue based on resource utilization.

Distributed Applications and Services

• Applications operate independently on hosts, exchanging messages via internet socket interfaces.
• Protocols determine message format and exchange order and govern actions taken during transmission or reception.
• Services like reliability and guaranteed rates are provided by hardware or software tied to devices.

Network Edge

• The network edge encompasses computer networks that connect to the internet, categorized as access networks.
• End-systems can be classified into clients and servers.
• Gateways are routers connecting access networks to ISPs.
• Access networks can be classified based on size (local area, home, wide area), topology (tree, star, ring, bus, point-to-point), and physical media (wired or wireless).