Download presentation
Presentation is loading. Please wait.
Published byTheodore Webb Modified over 8 years ago
1
SESI X
2
Network ◦ An interconnected chain, group or system Number of possible connections on a network is N * (N-1) ◦ Where N = number of nodes (points of connections on the network) ◦ Example, if there are 10 computers on a network, there are 10 * 9 = 90 possible connections
3
The usefulness of a network equals the square of the number of users On a small network, a change in technology affects technology only On a large network like the Internet, a change in technology affects social, political and economic systems
4
Telecommunications ◦ Exchange of information in any form (voice, data, text, images, audio, video) over networks
6
Information systems that use common standards for hardware, software, applications and networks Internet networking technologies are a common standard for open systems Connectivity: ◦ Ability of networked computers to easily access and communicate with each other and share information Interoperability: ◦ The ability of an open system to enable end user applications to be accomplished using different varieties of computer systems, software packages, and databases provided by a variety of interconnected networks
7
Any programming that serves to “glue together” two separate programs
8
Rapid change from analog to digital network technologies Analog: voice-oriented transmission, sound waves Digital: discrete pulse transmission Digital allows: ◦ Higher transmission speed ◦ Larger amounts of information ◦ Greater economy ◦ Lower error rates ◦ Multiple forms of communications on same circuit
9
Next generation of the Internet High-performance network In use at 200 universities, scientific institutions, communications corporations
11
Over 46 million servers (2004) 710 – 945 million users (2004) No central computer system No governing body No one owns it
12
ISP ◦ A company that specializes in providing easy access to the Internet ◦ For a monthly fee, you get software, user name, password and access ISPs are connect to one another through network access points
16
A network inside an organization ◦ That uses Internet technologies (such as Web browsers and servers, TCP/IP protocols, HTML, etc.) ◦ To provide an Internet-like environment within the organization ◦ For information sharing, communications, collaboration and support of business processes ◦ Protected by security measures ◦ Can be accessed by authorized users through the Internet
18
Network links that use Internet technologies ◦ To connect the Intranet of a business ◦ With the Intranets of its customers, suppliers or other business partners
20
Any arrangement where a sender transmits a message to a receiver over a channel consisting of some type of medium
21
Terminals: any input/output device that uses networks to transmit or receive data Telecommunications Processors: devices that support data transmission and reception Telecommunications Channels: media over which data are transmitted and received Computers: all sizes and types Telecommunications Control Software: programs that control telecommunications activities
23
Telecommunications network that covers a large geographic area Source: Courtesy of Cisco Systems Inc.
24
Connect computers within a limited physical area such as an office, classroom, or building
25
A secure network that uses the Internet as its backbone but relies on firewalls, encryption and other security A pipe traveling through the Internet
27
Clients: End user personal computers or networked computers Interconnected by LANs Servers: manage networks Processing shared between clients and servers
29
Networks are the central computing resource of the organization Thin clients: network computers and other clients provide a browser-based user interface
30
Networks that connect from one PC to another PC Common use is the downloading and trading of files
32
Twisted-pair wire: ◦ Ordinary telephone wire ◦ Copper wire twisted into pairs Source: Phil Degginger/Getty Images.
33
Coaxial cable: ◦ Sturdy copper or aluminum wire wrapped with spacers to insulate and protect it Source: Ryan McVay/Getty Images.
34
Fiber-optic cable: ◦ One or more hair-thin filaments of glass fiber wrapped in a protective jacket Source: CMCD/Getty Images.
35
Network providers use fiber optic to provide backbone But houses are connected to the backbone via twisted-pair Cannot get the benefit of the faster, better technology
36
Terrestrial microwave ◦ Earthbound microwave systems that transmit high- speed radio signals in a line-of-sight path ◦ Between relay systems spaced approximately 30- miles apart Communications satellites ◦ Satellite serves as relay stations for communications signals ◦ Uses microwave radio signals
37
Cellular and PCS telephone and pager systems ◦ Divide the geographic area into small areas or cells ◦ Each cell has transmitter or radio relay antenna to send message from one cell to another Wireless LANs ◦ Radio signals within an office or building ◦ Connect PCs to networks Bluetooth ◦ Short-range wireless technology ◦ To connect PC to peripherals such as printer
38
Connect portable communications devices to the Internet
39
Modems ◦ Convert digital signals from a computer into ◦ Analog frequencies that can be transmitted over ordinary telephone lines
41
Switch – makes connections between telecommunications circuits in a network Router – intelligent communications processor that interconnects networks based on different protocols Hub – a port switching communications processor Gateway – connects networks using different communications architectures
43
Multiplexer ◦ Allows a single communications channel to carry simultaneous data transmissions from many terminals
44
Used by servers and other computers to manage network performance Network Operating Systems Middleware
45
Traffic Management – manage network resources and traffic to avoid congestion and optimize service levels to users Security – provide authentication, encryption, firewall, auditing and enforcement Network Monitoring – troubleshoot and watch over the network, informing network administrators of potential problems before they occur Capacity Planning – survey network resources and traffic patterns and users’ needs to determine how best to accommodate the needs of the network as it grows and changes
46
Network Topologies Topology: structure of a network Star: ties end user computers to a central computer Ring: ties local computer processors together in a ring on a relatively equal basis Bus: local processors share the same communications channel
48
Protocol: standard set of rules and procedures for the control of communications in a network Network Architecture: ◦ Master plan of standard protocols, hardware, software and interfaces between end users and computer systems ◦ Goal of promoting an open, simple, flexible, and efficient telecommunications environment
49
Open Systems Interconnection (OSI) Model ◦ A seven-layer model that serves as a standard model for network architectures ◦ Model for how messages should be transmitted between two points in a network ◦ Each layer adds functions Transmission Control Protocol / Internet Protocol (TCP/IP) ◦ A five layer telecommunications protocol used by the Internet
51
Using an Internet connection to pass voice data using IP Voice over IP (VoIP) Skips standard long-distance phone charges
52
Bandwidth ◦ Frequency range of a telecommunications channel ◦ Determines transmission rate ◦ Classified in bits per second (bps) Transmission Rates: ◦ Narrow-band – low-speed ◦ Broadband – high-speed
54
Circuit Switching ◦ Switch opens a circuit to establish a link between a sender and receiver ◦ it remains open until the communication session is completed Packet Switching ◦ Break messages into groups called packets ◦ Transmit packets separately
55
Ensure that anyone anywhere on one network Can communicate With anyone anywhere on another network Telecommunications as discussed in this chapter wouldn’t be possible without interoperability
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.