LBSC 690 Session 3 Networking

Analog to Digital We live in an analog world: Sound, temperature, light, etc. –Sensory inputs. Are continuous signals. Can assume all (essentially infinite) values in a given interval. Basis for analog computers: –Uses electrical voltage/current to variables. to represent.

Digital Discrete representation: assumes a finite number of values in a given interval. Basis for digital computers: –Use 2 discrete values to represent data, & instructions. (Binary system). Analog signals converted to digital by Pulse Code Modulation (PCM).

PCM Three step process: Analog signal is sampled: –Nyquist’s Theorem. Samples are quantized. Quantized samples are encoded into binary digits, called “bits” for short. See handout.

Evolution Computers initially stand alone. Need to communicate. –Transmit data at a distance. Communications: –Data communication. –Telecommunication: Provides electrical communications at a distance. Service provided by a number of companies internationally. –The “telecommunications industry.”

Telecommunications Industry Carriers: –LECs (RBOCs: 7 to 4); CLECs. –IXCs. Internet Service Providers (ISPs). Vendors/Consultants & Manufacturers. Judicial/Political/Legislative: –Regulatory agencies. Standards Making Organizations. Customers: business & residential. Technology and research.

Networking Simplest form: Directly connect two communicating devices. Not practical solution. –Problem of topology: How to deal with fully connected mesh. Need network. –Nodes and segments.

The Universal Seven Part Data Model DTE DCE DTE DTE: Data Terminal Equipment DCE: Data Communication Equipment DTE/DCE Interface Transmission Channel DCE/DTE Interface

Network (Cont’d.) NETWORK N N N N S S S S S: Network Station N: Network Node “Local loop”

Network Types Switched Communication Network: Circuit-switched. Packet–-switched. Broadcast communication Network: Packet radio network. Satellite network. Local area network.

Generic Switching Network Reference handout.

LANs What are they? Need & functions. Hardware/software components. Concept of packets. Ethernet and token ring. Need to interconnect LANs.

LANs Data communication facilities designed to provide high-speed switched connections between processors peripherals and terminals within a local area, e.g., buildings or a campus.

LAN Functions File sharing Printer sharing CD ROM sharing On-line databases Groupware OPAC access Dial in & out Fax in & out Voice-video-multi- media Internet access

LAN Benefits Shared access Increased security Application and data highway –Adding new applications is done once (on server) Support services more effective and lower cost

LAN Installation Network Operating System (NOS). Network Interface Cards (NIC). Cabling and connectors. Concentrators/Hubs/ Switches. Network Servers: –File, Print, Communication, etc.

TRAINING Network Management: –Network Administrator & Support Personnel. –Certification. –Continuing education. User training.

Ethernet Developed in 1973 at Xerox Corporation’s Palo Alto Research Center (PARC). Developed by Bob Metcalfe. Uses the Ethernet Protocol. Protocol: A code prescribing strict adherence to correct etiquette and precedence. Communication protocols: symbols (Character set), rules for sequence and timing of messages, and procedures for error detection and handling. Messages broken into frames (packets). –With source address and destination address.

Network Topology Bus Star Ring Mesh Hybrid

Ethernet Broadcast Carrier Sense Multiple Access/Collision Detection (CSMA/CD) Collision retry (random wait) Need for repeaters Hubs Switches Bridges (internetting)

Ethernet Media 4-wire phone 3kbps 200 ft. UTP100Mbps100 ft. STP 16Mbps100 ft. Coax 10Mbps500 ft. Fiberoptic 10Gbps2-5 km.

The Internet Historical development. TCP/IP Protocol Suite. Telnet. FTP. . Assignment 1: –Two exercises. Packet switching. Addressing: URLs.

Packet Switching General Switching Diagram: –Reference Handout

Modems Function: –Modulation – demodulation. Types and speeds: –ISDN. –Cable. –ADSL. –Satellite

World Wide Web (WWW) Historical development. HTTP. HTML. XML. Multimedia.

Trends Convergence. Voice over IP (VIP). Wireless. Remote access. Remote device control.