COMPUTER NETWORKS and INTERNETS Chapter 1 Introduction and overview

Introductions Name Experience Major

review Base 10 (Decimal) Base 2 (Binary) Network Devices Switch Hub Router

Growth of computer networking In the late 1960’s the first workable prototype of the Internet was ARPANET (Advanced Research projects Agency Network) Funded by the U.S. Department of Defense 1969 - UCLA, Stanford, University of California-Santa Barbara, and University of Utah installed first nodes First message was “LO” meaning to Login 1973 Global networking (Internet) is born when University College of London (England) and Royal Radar Establishment (Norway) connect to ARPANET. Public population goes World Wide Web 1990 – HyperText Markup Language (HTML) is developed. This is used today. 1991 – World Wide Web (WWW) is introduced to the public 1994 – Netscape (Internet Browser) and Yahoo is created.

Growth of computer networking

The five key aspects of networking 1. Network Applications and Network Programing Span a wide range that includes Email File upload or download Web browsing Telephone calls Distributed database access Video conferencing 2. Data Communications Data communication refers to the study of low-level mechanisms and technologies used to send information across a physical communication medium. Copper wire, light beam, radio wave

The five key aspects of networking 3. Packet Switching and Networking Technologies Early communication networks evolved from a physical wire connecting two parties to complete a circuit. Similar to telephone switch board Packet switching changed networking in a fundamental way Instead of a dedicated circuit, multiple senders transmit data over a shared network Packet switching divides data into small blocks called packets. Devices (routers, switches, etc.) are throughout the network that contains information on how o reach end device.

The five key aspects of networking 4. Internetworking with TCP/IP What does a protocol mean Transmission Control Protocol/Internet Protocol (TCP/IP) Internetworking is a concept that allows computers (end devices) to communicate together.

The five key aspects of networking 5. Additional Networking Concepts and Technologies Assessing network performance Allowing multimedia and IP telephony Home automation

Public and private parts of the internet Public network is available to subscribers. Pay for subscription (and register for the address). Knows as a service provider. Internet Service Provider (ISP) Routed on Internet Private network is controlled by one particular group Consumer Least expensive owned by an individual. Probably a wireless router in home. Small Office/Home Office (SOHO) Connects two or more (typically less than 10) computers together for the Internet. Most are battery backup to minimize interruptions. Small-to-medium business (SMB) Many computers in multiple offices. Typically uses several routers Large enterprise A lot of IT infrastructure. Several geographical sites.

Networks, interoperability, and standards Communications always involves at least two entities Communications involves many details All agree on the voltage Exact way electrical signals are used to represent data Initiate and conduct communication Format of the message

Protocol suites and layering models A set of protocols must be constructed carefully to ensure that the resulting communications system is both complete and efficient Protocols are designed in complete cooperative sets called suites or families Each protocol in a suite handles one aspect of communication. Together all protocols in the suite handle all aspects of communication. Hardware failure and other exceptional conditions A layer model describes how all aspects of communication work together. The visual appearance of figures used to illustrate layering is called stack

Protocol suites and layering models (cont.)

How data passes through the layers

Headers and layers Encapsulation / Deencapsulation Protocol Data Units (PDU) Segments = Transport Packets = Internet, Frames = Network Access (Interface) or MAC Bits = Physical