Transcript Chapter 4 – Data Communication Fundamental

Data Communication & Networking in
Manufacturing System
Nanang Ali Sutisna
Master Eng. in Computer Integrated Manufacture
Senior PLM Consultant, IBM Indonesia (Retired)
Senior Manager, Product Development
Multistrada Arah Sarana
Data Communication & Networking in
Manufacturing System
Chapter 4
Data Communication
Fundamental
What is data communication?
 Not to be confused with telecommunication
• Any process that permits the passage from a sender to one
or more receivers of information of any nature, delivered in
any easy to use form by any electromagnetic system.
 Data communication
• Defined as a subset of telecommunication involving the
transmission of data to and from computers and
components of computer systems.
• More specifically data communication is transmitted via
mediums such as wires, coaxial cables, fiber optics, or radiated
electromagnetic waves such as broadcast radio, infrared light,
microwaves, and satellites.
History of Telecommunications
 Invention of telegraph Samuel Morse – 1837
 Invention of telephone- Alexander Graham
Bell – 1876
 Development of wireless By ??? – 1896
 Concept of universal access and growth of
AT&T
 Divestiture of AT&T—what year??
History of Telecommunications
Continued….
 Telecommunications Act of 1996
 Three main developments that led to
the growth of data communications
systems:
• Large-scale integration of circuits reduced the
cost and size of terminals and comm equipment
• Developments of software systems made
establishment of communication networks easy
• Competition among providers of transmission
facilities reduced the cost of data circuits
History of Data Communication
 Transistor developed by Bell Labs 1947
 Hush-a-Phone Case
 Carterphone case
 MCI and Long Distance
 Creation of networks (LAN’s and
WAN’s)
 Data Link Protocols
 Microcomputers
History of the Internet
1836
-- Telegraph. Cooke and Wheatstone patent it. Why is this relevant?
•Revolutionized human telecommunications.
•Morse Code a series of dots and dashes used to communicate between humans.
This is not a million miles away from how computers communicate via (binary 0/1)
data today. Although it is much slower!!
1858-1866
-- Transatlantic cable. Allowed direct instantaneous communication across the
Atlantic. Why is this relevant?
•Today, cables connect all continents and are still a main hub of telecommunications.
1876
-- Telephone. Alexander Graham Bell Exhibits.
Why is this relevant?
•Telephones exchanges provide the backbone of Internet connections today.
•Modems provide Digital to Audio conversions to allow computers to connect over
the telephone network.
1957
-- USSR launches Sputnik, first artificial earth satellite. Why is this relevant?
•The start of global telecommunications. Satellites play an important role in transmitting
all sorts of data today.
•In response, US forms the Advanced Research Projects Agency (ARPA) within the
Department of Defense (DoD) to establish US lead in science and technology applicable
to the military.
1962 - 1968
-- Packet-switching (PS) networks developed Why is this relevant?
•As we will see later the Internet relies on packets to transfer data.
•The origin is military : for utmost security in transferring information of networks (no
single outage point).
•Data is split into tiny packets that may take different routes to a destination.
•Hard to eavesdrop on messages.
•More than one route available -- if one route goes down another may be followed.
Networks can withstand large scale destruction (Nuclear attack - This was the time of the
Cold War).
1969
-- Birth of Internet
ARPANET commissioned by DoD for research into networking. Why is this relevant?
•First node at UCLA (Los Angeles) closely followed by nodes at Stanford Research Institute, UCSB
(Santa Barbara) and U of Utah (4 Nodes).
1971
-- People communicate over a network
•15 nodes (23 hosts) on ARPANET.
•E-mail invented -- a program to send messages across a distributed network. Why is this relevant?
E-mail is still the main way of inter-person communication on the Internet today.
You will make extensive use of E-mail for the rest of your life.
1972
-- Computers can connect more freely and easily
•First public demonstration of ARPANET between 40 machines.
•Internetworking Working Group (INWG) created to address need for establishing agreed upon
protocols.
Why is this relevant?
Telnet specification
Telnet is still a relevant means of inter-machine connection today.
1973
-- Global Networking becomes a reality
•First international connections to the ARPANET: University College of London (England)
and Royal Radar Establishment (Norway)
•Ethernet outlined -- this how local networks are basically connected today.
•Internet ideas started.
•Gateway architecture sketched on back of envelope in hotel lobby in San Francisco.
Gateways define how large networks (maybe of different architecture) can be connected
together.
•File Transfer protocol specified -- how computers send and receive data.
1974
-- Packets become mode of transfer
•Transmission Control Program (TCP) specified. Packet network Intercommunication -the basis of Internet Communication.
•Telnet, a commercial version of ARPANET, opened -- the first public packet data service.
1976
-- Networking comes to many
•Queen Elizabeth sends out an e-mail.
•UUCP (Unix-to-Unix CoPy) developed at AT&T Bell Labs and distributed with UNIX.
Why is this relevant?
UNIX was and still is the main operating system used by universities and research
establishments.
These machines could now ``talk'' over a network.
Networking exposed to many users worldwide.
1977
-- E-mail takes off, Internet becomes a reality
•Number of hosts breaks 100.
•THEORYNET provides electronic mail to over 100 researchers in computer science
(using a locally developed E-mail system and TELNET for access to server).
•Mail specification
•First demonstration of ARPANET/Packet Radio Net/SATNET operation of Internet
protocols over gateways.
1979
-- News Groups born
•Computer Science Department research computer network established in USA.
•USENET established using UUCP.
Why is this relevant?
USENET still thrives today.
A collection of discussions groups, news groups.
3 news groups established by the end of the year
Almost any topic now has a discussion group.
•First MUD (Multiuser Dungeon) -- interactive multiuser sites. Interactive adventure
games, board games, rich and detailed databases.
•ARPA establishes the Internet Configuration Control Board (ICCB).
•Packet Radio Network (PRNET) experiment starts with ARPA funding. Most
communications take place between mobile vans.
1981
-- Things start to come together
•BITNET, the "Because It's Time NETwork" Started as a cooperative network at the City University of
New York, with the first connection to Yale
Provides electronic mail and listserv servers to distribute information, as well as file transfers
•CSNET (Computer Science NETwork) established to provide networking services (specially E-mail)
to university scientists with no access to ARPANET. CSNET later becomes known as the Computer
and Science Network.
1982
-- TCP/IP defines future communication
•DCA and ARPA establishes the Transmission Control Protocol (TCP) and Internet Protocol (IP), as
the protocol suite, commonly known as TCP/IP, for ARPANET.
Why is this relevant?
Leads to one of the first definitions of an internet as a connected set of networks, specifically
those using TCP/IP, and Internet as connected TCP/IP internets.
•EUnet (European UNIX Network) is created by EUUG to provide E-mail and USENET services.
Original connections between the Netherlands, Denmark, Sweden, and UK
External Gateway Protocol specification -- EGP is used for gateways between
(different architecture) networks.
1983
-- Internet gets bigger
•Name server developed.
Why is this relevant?
Large number of nodes.
Hard to remember exact paths
Use meaningful names instead.
•Desktop workstations come into being.
Why is this relevant?
Many with Berkeley UNIX which includes IP networking software.
Need switches from having a single, large time sharing computer connected to
Internet per site, to connection of an entire local network.
•Internet Activities Board (IAB) established, replacing ICCB
•Berkeley releases new version of UNIX 4.2BSD incorporating TCP/IP.
•EARN (European Academic and Research Network) established on similar lines to BITNET
1984
-- Growth of Internet Continues
•Number of hosts breaks 1,000.
•Domain Name Server (DNS) introduced.
instead of 123.456.789.10
it is easier to remember something like
www.myuniversity.mydept.mynetwork.mycountry
( e.g. www.cs.cf.ac.uk).
•JANET (Joint Academic Network) established in the UK
•Moderated newsgroups introduced on USENET.
1986
-- Power of Internet Realised
•5, 000 Hosts. 241 News groups.
•NSFNET created (backbone speed of 56 Kbps)
•NSF establishes 5 super-computing centers to provide high-computing power for all -This allows an explosion of connections, especially from universities.
•Network News Transfer Protocol (NNTP) designed to enhance Usenet news
performance over TCP/IP.
1987
-- Commercialization of Internet Born
•Number of hosts 28,000.
•UUNET is founded with Usenix funds to provide commercial UUCP and Usenet access.
1988
•2 November - Internet worm burrows through the Net, affecting ~6,000 of the 60,000
hosts on the Internet
•CERT (Computer Emergency Response Team) formed by DARPA in response to the
needs exhibited during the Morris worm incident. The worm is the only advisory issued
this year.
•NSFNET backbone upgraded to T1 (1.544 Mbps)
•Internet Relay Chat (IRC) developed
1989
-- Large growth in Internet
•Number of hosts breaks 100,000
•First relays between a commercial electronic mail carrier and the Internet
•Internet Engineering Task Force (IETF) and Internet Research Task Force (IRTF) comes
into existence under the IAB
1990
-- Expansion of Internet continues
• Electronic Frontier Foundation (EFF) is founded by Mitch Kapor
•300,000 Hosts. 1,000 News groups
•ARPANET ceases to exist
•Archie released files can be searched and retrieved (FTP) by name.
•The World comes on-line (world.std.com), becoming the first commercial provider of Internet dialup access.
1991
-- Modernization Begins
•Commercial Internet eXchange (CIX) Association, Inc. formed after NSF lifts restrictions on the
commercial use of the Net.
•PGP (Pretty Good Privacy) released by Philip Zimmerman
•US High Performance Computing Act (Gore 1) establishes the National Research and Education
Network (NREN)
•Wide Area Information Servers (WAIS) Why is relevant?
Provides a mechanism for indexing and accessing information on the Internet.
Large bodies of knowledge available: E-mail messages, text, electronic books, Usenet articles,
computer code, image, graphics, sound files, databases etc..
These form the basis of the index of information we see on WWW today.
Powerful search techniques implemented. Keyword search.
1991 (cont)
-- Friendly User Interface to WWW established
•Gopher released by Paul Lindner and Mark P. McCahill from the U of Minnesota. Why is
relevant?
Text based, menu-driven interface to access internet resources.
No need to remember or even know complex computer command. User Friendly
Interface (?).
Largely superseded by WWW, these days.
-- Most Important development to date
•World-Wide Web (WWW) released by CERN; Tim Berners-Lee developer. Why is
relevant?
Originally developed to provide a distributed hypermedia system.
Easy access to any form of information anywhere in the world.
Initially non-graphic (this came later, MOSAIC, 1993).
Revolutionized modern communications and even our, way of life (?).
•NSFNET backbone upgraded to T3 (44.736 Mbps). NSFNET traffic passes 1 trillion
bytes/month and 10 billion packets/month
•Start of JANET IP Service (JIPS) using TCP/IP within the UK academic network.
1992
- Multimedia changes the face of the Internet
•Number of hosts breaks 1 Million. News groups 4,000
•Internet Society (ISOC) is chartered.
•First MBONE audio multicast (March) and video multicast (November).
•The term "Surfing the Internet" is coined by Jean Armour Polly.
1993
-- The WWW Revolution truly begins
•Number of Hosts 2 Million. 600 WWW sites.
•InterNIC created by NSF to provide specific Internet services
directory and database services
registration services
information services
•Business and Media really take notice of the Internet.
•US White House and United Nations (UN) comes on-line.
•Mosaic takes the Internet by storm. Why is this relevant?
User Friendly Graphical Front End to the World Wide Web.
Develops into Netscape -- most popular WWW browser to date.
1994
-- Commercialization begins
•Number of Hosts 3 Million. 10,000 WWW sites. 10,000 News groups.
•ARPANET/Internet celebrates 25th anniversary
•Local communities begin to be wired up directly to the Internet (Lexington and Cambridge, Mass.,
USA)
•US Senate and House provide information servers
•Shopping malls, banks arrive on the Internet
A new way of life
You can now order pizza from the Hut online in the US.
First Virtual, the first cyberbank, open up for business
•NSFNET traffic passes 10 trillion bytes/month
•WWW edges out telnet to become 2nd most popular service on the Net (behind ftp-data) based on
% of packets and bytes traffic distribution on NSFNET
•UK's HM Treasury on-line (http://www.hm-treasury.gov.uk/)
•First cyberstation, RT-FM, broadcasts from Interop in Las Vegas
•Arizona law firm of Canter & Siegel "spams" the Internet with email advertising green card lottery
services; Net citizens flame back
1995
-- Commercialization continues
•6.5 Million Hosts, 100,000 WWW Sites.
•NSFNET reverts back to a research network. Main US backbone traffic now routed through
interconnected network providers
•WWW surpasses ftp-data in March as the service with greatest traffic on NSFNet based on packet
count, and in April based on byte count
•Traditional online dial-up systems (Compuserve, America Online, Prodigy) begin to provide Internet
access
•A number of Net related companies go public, with Netscape leading the pack.
•Registration of domain names is no longer free.
•Technologies of the Year: WWW, Search engines (WAIS development).
•RealAudio, an audio streaming technology, lets the Net hear in near real-time
RFC 1882: The 12-Days of Technology Before Christmas
Country domains registered: Ethiopia (ET), Cote d'Ivoire (CI), Cook Islands (CK) Cayman Islands (KY),
Anguilla (AI), Gibraltar (GI), Vatican (VA), Kiribati (KI), Kyrgyzstan (KG), Madagascar (MG), Mauritius
(MU), Micronesia (FM), Monaco (MC), Mongolia (MN), Nepal (NP), Nigeria (NG), Western Samoa
(WS), San Marino (SM), Tanzania (TZ), Tonga (TO), Uganda (UG), Vanuatu (VU)
Top 10 Domains by Host #: com, edu, net, gov, mil, org, de, uk, ca, au
•New WWW technologies emerge
Mobile code (JAVA, JAVAscript, ActiveX),
Virtual environments (VRML),
Collaborative tools (CU-SeeMe)
1996
-- Microsoft enters
•12.8 Million Hosts, 0.5 Million WWW Sites.
•Internet phones catch the attention of US telecommunication companies who ask the US Congress to ban the
technology (which has been around for years)
•The WWW browser war begins , fought primarily between Netscape and Microsoft, has rushed in a new age in
software development, whereby new releases are made quarterly with the help of Internet users eager to test
upcoming (beta) versions.
•The controversial US Communications Decency Act (CDA) becomes law in the US in order to prohibit distribution of
indecent materials over the Net. A few months later a three-judge panel imposes an injunction against its
enforcement. Supreme Court unanimously rules most of it unconstitutional in 1997.
•Various ISPs suffer extended service outages, bringing into question whether they will be able to handle the growing
number of users. AOL (19 hours), Netcom (13 hours), AT&T WorldNet (28 hours - email only)
•Domain name tv.com sold to CNET for US$15,000
•MCI upgrades Internet backbone adding ~13,000 ports, bringing the effective speed from 155Mbps to 622Mbps.
•The Internet Ad Hoc Committee announces plans to add 7 new generic Top Level Domains (gTLD): .firm, .store, .web,
.arts, .rec, .info, .nom. The IAHC plan also calls for a competing group of domain registrars worldwide.
•RFC 1925: The Twelve Networking Truths
•Restrictions on Internet use around the world:
China: requires users and ISPs to register with the police
Germany: cuts off access to some newsgroups carried on Compuserve
Saudi Arabia: confines Internet access to universities and hospitals
Singapore: requires political and religious content providers to register with the state
New Zealand: classifies computer disks as "publications" that can be censored and seized
source: Human Rights Watch
1997
-- What Next?
•19.5 Million Hosts, 1 Million WWW sites, 71,618 Newsgroups.
•Domain name business.com sold for US$150,000
•Early in the morning of 17 July, human error at Network Solutions causes the DNS table for .com
and .net domains to become corrupted, making millions of systems unreachable.
•In protest of the DNS monopoly, AlterNIC's owner, Eugene Kashpureff, hacks DNS so users going to
www.internic.net end up at www.alternic.net
Technologies of the Year: Push, Multicasting
1998 •US Depart of Commerce (DoC) releases the Green Paper outlining its plan to privatize DNS on 30
January. This is followed up by a White Paper on June 5
•Network Solutions registers its 2 millionth domain on 4 May
•Canada kicks off CA*net 3, the first national optical internet
•Compaq pays US$3.3million for altavista.com
•ABCNews.com accidentally posts test US election returns one day early (2 November)
•French Internet users give up their access on 13 December to boycott France Telecom's local
phone charges (which are in addition to the ISP charge)
•Open source software comes of age
•Technologies of the Year: E-Commerce, E-Auctions, Portals
•Emerging Technologies: E-Trade, XML, Intrusion Detection
1999
•First Internet Bank of Indiana, the first full-service bank available only on the Net, opens for
business on 22 February
•IBM becomes the first Corporate partner to be approved for Internet2 access
•European Parliament proposes banning the caching of Web pages by ISPs
•US State Court rules that domain names are property that may be garnished
•MCI/Worldcom, the vBNS provider for NSF, begins upgrading the US backbone to 2.5GBps
•A forged Web page made to look like a Bloomberg financial news story raised shares of a small
technology company by 31% on 7 April.
•First large-scale Cyberwar takes place simultaneously with the war in Serbia/Kosovo
•The Web becomes the focal point of British politics as a list of MI6 agents is released on a UK Web
site. Though forced to remove the list from the site, it was too late as the list had already been
replicated across the Net. (15 May)
•Activists Net-wide target the world's financial centers on 18 June, timed to coincide with the G8
Summit. Little actual impact is reported.
•business.com is sold for US$7.5million (it was purchased in 1997 for US$150,000 (30 Nov)
•Technologies of the Year: E-Trade, Online Banking, MP3
•Emerging Technologies: Net-Cell Phones, Thin Computing, Embedded Computing
•Viruses of the Year: Melissa (March), ExploreZip (June)
2000
•The US timekeeper (USNO) and a few other time services around the world report the new year as
19100 on 1 Jan
•A massive denial of service attack is launched against major web sites, including Yahoo, Amazon, and
eBay in early February
•Web size estimates by NEC-RI and Inktomi surpass 1 billion indexable pages
•Hacks of the Year: RSA Security (Feb), Apache (May), Nike (June)
•Technologies of the Year: ASP, NAPSTER?, IPV6?
•Viruses of the Year: Love Letter (May)
•Current up to date web user statistics
Framework for Global Electronic
Commerce
 A Framework for Global Electronic Commerce
was released in 1997
 It’s release underscores the importance of
Internet-based commerce in the global
economy
 It outlines several guiding principles for ecommerce planners and strategists
Table 1-3
Table 1-4
Features of Communication
 Four things required
• Sender, receiver, medium, and message
 Types of messages
•
•
•
•
•
•
File
Request
Response
Status
Control
Correspondence
 Understandability
 Error Detection
Network Applications
 The network applications environment
consists of several important components:
• Application programs
• Operating systems
• Data communication systems
• Database management systems
 The application environment is illustrated in
Figure 1-10
Figure 1-10
Online System Requirements
 Response Time
 Throughput
 Consistency
 Flexibility
Online Systems Requirements Continued
 Availability
 Reliability
• Mean time between failure (MTBF)
• Mean time to repair (MTTR)
• Fault Tolerance
 Recovery
 Security
Business Data Communication Applications
 Major data communication applications
include:
• E-mail
• Groupware
• Knowledge management systems
• E-commerce and e-business applications
• Wireless applications
Groupware Applications
 Group calendar
systems
 Electronic filing
cabinets
 Project
management
software
 Group support
systems
 Electronic
meeting and
videoconferencin
g systems
 Document
management
systems (image
processing
systems)
Other Data Communication Applications
 Batch
 Interactive
 Data entry
applications
 Sensor-based
applications
 Distributed
applications
 Combined
applications
applications
 Inquiry/response
applications
applications
Application Service Providers
 Many businesses have turned to third-
party services for some or all of their
business and data communications
applications
 Application service providers (ASPs)
are third-party organizations that
manage and distribute software and
services to other companies over the
Web
 Many ASPs specialize in integrated ecommerce and e-business applications
Business Data Communications Issues
 Major data communications issues include:
• Cost-effectiveness
• The Internet
• Bandwidth
• Evolving technologies
• Convergence
• Standards
• Privacy and security
Important Standard-Setting Organizations
Table 1-5
Business Data Communication Careers
 There are numerous job opportunities and
career paths for individuals interested in data
communications and networking
 Table 1-6 includes examples of data
communication job titles
 Table 1-7 summarizes some of the major
professional certifications for networking and
data communications specialists
Introduction to Networks
 Can be defined as a single computer , called a
host, together with communication circuits,
communication equipment, and terminals.
 There are many different types of network
configurations (see figures1-4 to 1-8)
Key Data Communication Concepts
 Session: communication dialog between network users







or applications
Network: interconnected group of computers and
communication devices
Node: a network-attached computer
Link: connects adjacent nodes (see Figure 1-4)
Path: end-to-end route within a network
Circuit: the conduit over which data travels
Packetizing: dividing messages into fixed-length
packets prior to transmission over a network’s
communication media
Routing: determining a message’s path from sending to
receiving nodes.
Store-and-Forward Systems
 Messages may be stored at
intermediate nodes along the
transmission path between sender and
receiver in store-and-forward systems
• This helps ensure message delivery without
obligating the sender to wait until a message is
delivered before transmitting other messages
• It also helps ensure message delivery in the case
of link or destination failure while the message is
in transit
• Store-and forward algorithms are valuable in
time-staged delivery systems and in networks
that assign priorities to different messages
Network Topology, Architecture, and
Complexity
 Network topology refers to the physical
layout of a network, the way that
nodes attach to the communication
medium
 Network architecture refers to the way
in which media, hardware, and
software are integrated to form a
network
 Network complexity is concerned with
extent to which network architectures
are simple or diverse in their make
• Figures 1-5, 1-6, and 1-7 illustrate various levels of
complexity
Figure 1-5
Figure 1-6
Telecom Channels
 Channels - the links by which data or
voice are transmitted between sending
and receiving devices in a network
• twisted wires
• coaxial cable
• fiber-optic cable
• backbone
• wireless
• microwave
• satellite
Telecom Channels – other Wireless
 Cellular
 Mobile data networks (2-way)
 PCS (personal communication systems)- to
the end user acts like cellular, but different
 Personal data assistants
 smart phones
Transmission Speeds
Medium
Speed
Cost
Twisted W
ire
Microwave
Satellite
Coaxial Cable
Fiber-Optic Cable
300 bps-10 Mbps
256 Kbps-100 Mbps
256 Kbps-100 Mbps
56 Kbps-200 Mbps
500 Kbps-10 Gbps
Low
High
Data Communication Frameworks
 Two major data communication frameworks
have been developed to help ensure that
networks meet business and communication
requirements:
• Open Systems Interconnection (OSI) reference
model developed by the International Standards
Organization (ISO)
• Transmission Control Protocol/Internet Protocol
(TCP/IP) suite
History of the OSI Model
 Open Systems Interconnected Model
• was created in the 70’s by the ISO (although the
CCITT came up with their own model)
• 10 different people got together and considered all
functions of communications
• was created because people realized that our
computers needed to talk to each other(and
there was no one dominant computer system)
• ISDN was a big factor
• 7 layers = 4 upper and 3 lower
OSI Reference Model in Practice
 The OSI reference model is used in
many ways:
• To provide assistance when troubleshooting
network problems
• To provide a common terminology and
framework for networking technology developers
• To facilitate the development of connectivity
standards needed for flexible open architectures
• To enable the development of protocol stacks
that allow network nodes to communicate with
one another
The OSI Model

THE OSI MODEL
LAYER
LAYER
LAYER
LAYER
7
6
5
4
Application
Presentation
Session
Transport
LAYER
LAYER
LAYER
3
2
1
Network
Data Link
Physical



LAYER 7– APPLICATION
The visual interface level between the user and the
network, or computer. (Ex Word, Excel, Access,
Email)
LAYER 6-- PRESENTATION
This layer is responsible for converting the visual
interface into a code that is then sent through the
computer or network. For example, this layer may
convert ASCII code (what many applications like
Word use) to an 8-bit code.
LAYER 5 – SESSION
This layer keeps track of whose turn it is to receive
traffic, basically it is a dialog control. This is the
level that acknowledges receipt of a transmission as
well as sends the message to the network.
LAYER 4 – TRANSPORT
All streams of data are received and combined into
one single stream so that data may be sent through
the network. Multiplexing and demultiplexing
occurs on this layer.
The OSI Model


THE OSI MODEL
LAYER
LAYER
LAYER
LAYER
7
6
5
4
Application
Presentation
Session
Transport


LAYER
LAYER
LAYER
3
2
1
Network
Data Link
Physical
BOTTOM/LOWER LAYERS
LAYER 3– NETWORK
On this level the router exists to determine if the
message is meant for the system or if it needs to be
redirected to its final destination. This is done by a
header system, which is programmed to accept or
reject depending if the header is the one used by the
network.
LAYER 2– DATA LINK
There is where a check of the message occurs. That
is the message is checked for the proper frame,
formation, synchronization, power level, voltage,
and wavelength. If the test is a successful, the
message is sent to the network layer to determine if
the message is truly meant for the system.
LAYER 1– PHYSICAL
Where the actual physical makeup of the message is
identified. That is the duration of bits, the right
number of bits, and the right wavelength is checked.
As with the other two layers, if this test is
successful, the message is sent up the chain.
OSI LAYER INTERACTIONS
Application
Process
DATA
Application
Process
Incoming Frame
Reduction
Outgoing Frame
Application
Construction
Presentation
PCI DATA
PCI APDU
Session
Transport
Network
Link
PCI PPDU
PCI SPDU
PCI TPDU
PCI NPDU
Physical
Application
Presentation
Session
Transport
Network
Link
Physical
encoded bit stream
TCP/IP Protocol Suite
 The TCP/IP suite provides insights into
the inner workings of the Internet
 Like the OSI model, the TCP/IP suite is
layered
• Because the protocols found at each layer are
independent of those at the other layers, a given
protocol can be modified without affecting those
found at other layers
• TCP/IP layers and layer-specific protocols are
illustrated in Figure 1-9
Moving Bits through the Network
Analog Signal
1
0
Digital Signal
1
1
1
0
0
digital
Computer
0
analog
Modem
digital
Modem
telephone lines
Computer
Putting It all Together
 Data Communications Supports
Applications
 The Operating System manages the
resources of the computer.
 There must however, be a system that
provides a bridge between applications
and the devices so they can
communicate—this is called a
Transaction Control Process (TCP)