Ninth Edition by William Stallings Chapter 1 Data Communications Data Networks and the Internet Data and Computer Communications Ninth Edition by William Stallings c Pearson Education Prentice Hall 2011 ID: 673658
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Data and Computer Communications
Ninth Editionby William Stallings
Chapter 1 – Data Communications, Data Networks, and the Internet
Data and Computer Communications, Ninth Edition by William Stallings, (c) Pearson Education - Prentice Hall, 2011Slide2
Data Communications, Data Networks, and the Internet
“The
fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point”Data communications deals with the transmission of signals in a reliable and efficient manner. -
The Mathematical
Theory of Communication, Claude Shannon Slide3
Technological Advancement
Driving Forces
Three different forces have consistently driven the architecture and evolution of data communications and networking facilities:Slide4
Changes in Networking Technology
changes in the way organizations do business
* Emergence of high-speed LANs
*
Digital electronics
* Corporate WAN needsSlide5
Convergence
Convergence refers to The merger of previously distinct telephony and information technologies and markets.Convergence can be thought in terms of three layers:
applicationsthese are seen by the end usersenterprise servicesservices the information network supplies to support applicationsinfrastructurecommunication links available to the enterprise Slide6
Convergence LayersSlide7
Benefits
Convergence benefits include:Slide8
Communications Model
the transmission of signals in a reliable and efficient manner
. Slide9
Communications Tasks
Transmission system utilization
Addressing
Interfacing
Routing
Signal generation
Recovery
Synchronization
Message formatting
Exchange management
Security
Error detection and correction
Network management
Flow control
key tasks that must be performed in a data communications systemSlide10
Data Communications Model
the transmission of signals in a reliable and efficient manner
. Slide11
The basic building block of any communications facility is the transmission line.
The business manager is concerned with a facility providing the
required capacity, with acceptable reliability, at minimum cost.
Capacity
Reliability
Cost
Transmission
Line
Transmission LinesSlide12
Transmission Mediums
Two mediums currently driving
the evolution of data communications transmission are: Fiber optic transmissions
and
Wireless transmissions
Slide13
Networking
Advances in technology have led to greatly increased capacity and the concept of integration, allowing equipment and networks to work simultaneously.Slide14
LANs and WANs
There are two broad categories of networks: Slide15
Wide Area Networks (WANs)
Span a large geographical areaRequire the crossing of public right-of-ways
Rely in part on common carrier circuitsTypically consist of a number of interconnected switching nodesSlide16
Wide Area Networks
Circuit switchingPacket switching
Recently the following have assumed major roles.Frame relayAsynchronous Transfer Mode (ATM)
WANs
have been implemented using one of two technologies
:Slide17
Circuit Switching
Uses a dedicated communications pathConnected sequence of physical links between nodesLogical channel dedicated on each link
Rapid transmissionThe most common example of circuit switching is the telephone networkSlide18
Packet Switching
Data are sent out in a sequence of small chunks called packetsPackets are passed from node to node along a path leading from source to destination
Packet-switching networks are commonly used for terminal-to-terminal computer and computer-to-computer communicationsSlide19
Packet Switching
Packet switching systems have large overheads to compensate for errors
Modern systems are more reliableErrors can be caught in end systemFrame Relay provides higher speedsoriginal packet-switching networks were designed with a data rate to the end user of about 64 kbps, frame relay networks are designed to operate efficiently at user data rates of up to 2 Mbps. Slide20
Frame Relay
Developed to take advantage of high data rates and low error rates
Operates at data rates of up to 2 MbpsRate of errors dramatically lowered thus reducing overhead of packet-switchingSlide21
Asynchronous Transfer Mode (ATM)
Referred to as cell relayCulmination of circuit switching and packet switchingUses fixed-length packets called cellsWorks in range of 10’s and 100’s of Mbps and in the Gbps range
Data rate on each channel dynamically set on demandSlide22
Local Area Networks (LAN)
A LAN is a communications network that interconnects a variety of devices and provides a means for information exchange among those devices. Slide23
Metropolitan Area Networks (MAN)
typically spanning a city / metro area with higher speed connections.Slide24
The Internet
Internet evolved from ARPANET
developed in 1969 by the Advanced Research Projects Agency (ARPA) of the U.S. Department of Defense.Developed to solve the dilemma of communicating across arbitrary, multiple, packet-switched networkTCP/IP provides the foundationSlide25
Internet Key Elements
key elements that comprise the Internet, whose purpose is to interconnect end systems, called
hosts
; including PCs, workstations, servers, mainframes, and so on. Most hosts that use the Internet are connected to a
network
, such as a local area network (LAN) or a wide area network (WAN). These networks are in turn connected by
routers
. Slide26
Internet Architecture
hosts grouped into LANs, linked to an
Internet service provider (ISP)
through a
point of presence (POP)
. The connection is made in a series of steps starting with the
customer premises equipment (CPE). ISPs can be classified as regional or backbone, with peering links between.Slide27
Internet TerminologySlide28
A Networking Configuration
typical communications and network elements in use today
The Internet consists of a number of interconnected routers that span the globe.
The routers forward packets of data from source to destination through the InternetSlide29
Summary
Trends challenging data communications:traffic growthdevelopment of new services
advances in technologyTransmission mediumsfiber opticwirelessNetwork categories:WANLANInternetevolved from the ARPANETTCP/IP foundation