Transcript ch_01_Network_Overview - Faculty Web Hosting

Standards

Clear visible standards.
 Students must have clear understandings learning
standards in the areas of
 learning goals,
 lecture notes
 assignments and
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getting basic academics and
applications skills.
I would like to establish a clear system of standards
learning standards are aligned with your
expectations and the expectations of the global
marketplace
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Standards
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Communication delivered over multiple
channels is more efficient than
communication over a single channel.
Multiple channels make it more likely that the
whole message will be received.
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An appropriate picture adds another
channel
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by making a visual connection to an abstract idea.
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PowerPoint makes it easy to create
visuals, and by using a template, makes it
easy to be consistent.
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Research-based principles for design
Power Point presentation
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Educational psychologist, Richard Mayer, posits a
theory of multimedia learning wherein he finds
seven research-based principles for design.
Students learn better
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2.
3.
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from words and pictures than from words alone
(Multimedia Principle)
when corresponding words and pictures are presented near
rather than far from each other on the page or screen (Special
Contiguity Principle)
when corresponding words and pictures are presented
simultaneously rather than successively (Temporal
Contiguity Principle)
Mayer, R. (2001). Multimedia Learning. Cambridge University Press.
Rodriguez, R. (2005) Theories Into Practice with Blackboard ONLINE, University of La
Verne.
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Lecture Notes presentation
Eyes are attracted to great contrast
●Contrast should fit information relevance
●Important information should have high contrast

I use color or/and color
●Less relevant details should have lower contrast
Context should be hierarchical
●Group related contexts
● More details should be indented
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Lecture Notes presentation
Our eyes are attracted to:
●Size
●Contrast
●Texture
●Depth
●Motion
To control focus, we use:
●Larger size
●Greater contrast
●Different color
●Hierarchy
●Should be easy to ignore lower levels as
familiarity increases
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●Sometimes
animation
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Lecture Notes presentation
Addition to that we introduce
1.
Hierarchy of bullets
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Nested bulleted and numbered lists
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2.
3.
4.
Level 1 item 1
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Level 2 item
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Level 2 item
Level 1 item 2
1.
Level 2 item
2.
Level 2 item
1
2
1
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Higher level more general info
Lower level more specific info
Key words in red
Important words in bold
Ability to learn from slides
Example:
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Distributed Computing
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Work distributed over networks
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N-Tier applications
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Split parts of applications over numerous computers
1.
User interface
2.
Business-logic processing
3.
Database
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Different parts interact when application runs
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My Lecture Notes:
Have tutorial values:
 Comply with research-based principles for
design Power Point presentation
 Concepts are presented visually with
many diagrams and pictures.
 They use visual aids (diagrams, pictures etc.)
and pictures are presented near each
other on the page or screen.
 The context is presented in the
hierarchical way, details are indented

Important key words are highlighted or written in
different color
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PART I
Overview of
Data Communications
and
Networking
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
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expanded by Jozef Goetz, 2009
Overview
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Chapters
Chapter 1 Introduction
Chapter 2 Network Models
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Chapter 1
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1.1 Data Communication
•The term telecommunication means communication at a
distance.
•The word data refers to information presented in
whatever form is agreed upon by the parties creating and
using the data.
•Data communications are the exchange of data
between two devices via some form of transmission
medium such as a wire cable.
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1.1 Data Communication
•Data communication is the transfer of data from one device to another via some form
of transmission medium.
•A data communications system must transmit data to the correct destination in
an accurate and timely manner.
A. Components
B. Data Representation
C. Direction of Data Flow
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A. Five components of data communication
are the message, sender, receiver, medium, and protocol.
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B. Data Representation
text,
 numbers,
 images,
 audio, and
 video
are different forms of information.
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C. Direction of Data Flow
Figure 1.2 Simplex
e.g. the keyboard and the monitor
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Figure 1.2 Half-duplex
e.g. Walkie-talkies, CB radios
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Figure 1.2
Full-duplex
e.g. 2 people are communicating by a tel. line
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1.2 Networks
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A network is a set of communication
devices connected by media links.
• A network is a set of devices (often referred to
as nodes) connected by communication links.
• A node can be a computer, printer, router
or any other device capable of sending
and/or receiving data generated by other
nodes on the network.
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1.2 Networks
1. Distributed Processing
• Task is divided
2. Network Criteria should be met
• Important:
1. Performance
• Metrics – they are contradictory
• Transit time (from A to B)
• Response time
• Throughput
-How much data is sent
• Delay
-traffic congestion
2. Reliability
• Measured by the freq. of failure
3. Security
• Protecting data from unauthorized
access and damage
3. Physical Structures
4. Categories of Networks
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ad 3. Physical Structures
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In a point-to-point connection, two and only two devices are connected by a dedicated link.
Physical Structures
Figure 1.3
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Point-to-point connection
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Multipoint connection
(timeshare connection – capacity)
Figure 1.3
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In a multipoint connection, three or more devices share a link.
1.2 NETWORKS
How do we categorize?
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Topology, geography
Technology
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Topologies
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Wide area networks - WAN
Metropolitan networks - MAN
Local area networks - LAN
Personal networks - PN
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Technologies
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Circuit switched
Packet switched
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4. Categories of Networks
A topology is the geometric representation of the relationship of
all the links and linking devices
Figure 1.4 Categories of topology (a network is layout physically)
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Figure 1.5
Fully connected mesh topology (for five devices)
Every device has a dedicated point to point link to every other device
How many physical links do we need for n nodes (devices)?
-’s:
•Expensive
•Huge amount of cabling
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Figure 1.6
Star topology
Each device has a dedicated point to point link only to a central controller, called a hub
If one device wants to send data to another.
•It sends the data to the controller, which then relays the data to the other connected device.
So, it doesn’t allow direct traffic between devices
-’s: If one link fails, only that link is effected.
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Figure 1.7 Bus topology is multipoint,
previous all were point to point
One long cable acts as a backbone
connection
+s:
•include ease of installation
nodes are connected to the bus cable by drop lines and taps
•cable redundancy is eliminated
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Figure 1.8
Ring topology
Each device has a dedicated point to point link only with 2 devices on either side of it.
When a device receives a signal intended for another device,
its repeater regenerates the bits and passes them along.
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Figure 1.9 A hybrid topology: a star backbone with three bus networks
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Figure 1.10 An isolated LAN connecting 12 computers to a hub in a closet
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Categories of networks
A network falls is determined by criteria:
1. Its size
2. Its ownership
3. The distance
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Networks
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LAN -- Local Area Network
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MAN -- Metropolitan Area Network
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Usually confined to a single building or group
of buildings
Connects computer resources in a local
geographical area e.g. city
WAN -- Wide Area Network
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Usually uses some form of public or
commercial communications network to
connect computers is widely dispersed
geographical areas e.g. regions, countries,
states, with a minimum distance typical of that
34between major metropolitan areas.
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LAN - Local Area Network
•Designed for a single office, campus, building or between nearby
buildings.
•LANs allow resources to be shared
•Hardware
•Software
•Data
between PCs or workstations.
•License restriction
• LANs are distinguished by three characteristics:
– size
restricted in size based on the size of the campus or building.
– transmission technology
broadcast networks
– topology
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LANs - Transmission
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• LANs are usually broadcast networks that are
connected by a cable that attaches all of the
computers together.
• LANs can run at speeds from 10Mbps to
10Gbps depending on the technology.
• LAN delays are usually small (microseconds)
and few errors (scrambled data) occur.
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LAN (Continued)
A given LAN use only one type of transmission medium.
Speed : 4-16 Mbps
Today: 10 Gbps
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MAN - Metropolitan Area Network
(e.g. cable TV)
Designed to extend over an entire city, connects LANs
LANs can be shared
- offices can be connected via a city
Best known example – a cable TV network.
Originally intended for TV only, it quickly became used for computer
networks once the cable companies determined that there was money to
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be made.
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WAN - Wide Area Network
Provides all transmission (data, video, image etc.) over large areas e.g. states, countries,
a continent , or the whole world.
In contrast to LANs may utilize public, leased, or private communication equipment.
• The user computers in a WAN are called hosts (owned by the customers).
• Host computers on various LANs are connected via a communication subnet (owned by
a tel company or Internet service provider).
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Wide Area Networks
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Relation between hosts on LANs and the
subnet.
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The subnet consists of routers and transmission
lines.
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A router is a specialized piece of switching hardware that is
responsible for determining the direction that data packets
should be sent.
Routers are responsible for directing data down transmission lines
from one LAN to another.
Figure 1.11 WANs: a. a switched WAN
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- use routers to coonect LANs and WANs
b. a point-to-point WAN
•leased line
•dial up connection
WAN can be as complex as the backbones that connect the Internet or a home computers
to the2009
Internet
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Wide Area Networks
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A stream of packets from sender to receiver.
A subnet is organized according to the principle called storeand-forward or packet-switched subnet
– The message sent by a process is broken down into smaller packets to
send.
– Each packet is sent out onto the network.
– As a packet arrives at a router, it is stored (store-and-forward) there
until the outgoing line is free. It is then sent on it’s way.
– All the packets make take the same or different routes depending on if
Jozef Goetz, 2009 they are individually routed or not.
A WAN connecting two LANs
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Figure 1.12 e.g.
A heterogeneous network made of four WANs and two LANs
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Subnets (cont’d)
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• It is possible to have a broadcast subnet.
• The best example is a satellite system, where
the data is broadcast to everyone.
• With a satellite, no routing occurs at the
satellite – it simply acts as a big dish to
bounce signals off of.
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Wireless Networks.
• Wireless networks can be divided into three
main categories:
A.– System Interconnection
B.– Wireless LANs
C.– Wireless WANs
• Lets take a look at these three categories…
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A. System Interconnection
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• We can use wireless technology to
interconnect our system.
– wireless mouse
– wireless keyboard
– wireless PDA
• Bluetooth is a wireless technology that would
allow all sorts of digital devices (cameras,
headsets, scanners, computers ) to “talk” to
each other just by being close.
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Wireless Networks
(a) Bluetooth configuration (master-slave paradigm,
master determines how long, when and
frequency slaves can use)
(b) Wireless LAN
Computers and printers can connect to the network with a radio
communication link.
There is usually a (or some) central access point or base station
where the radio connections are converted to wire connections.
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B. Wireless LANs
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• Computers may also be able to talk directly
to one another if close enough together.
Wireless is great for old homes you don’t want to wire and
laptops that you want to be able to move around with.
• The standard is IEEE 802.11.
• It works on the same frequency as 2.4 GHz
portable phones and Bluetooth.
There are some compatibility issues between 802.11 and
Bluetooth that have to be worked out.
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C. Wireless WANs – IEEE 802.16
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• Cell phone networks are a good example
of wireless WANs.
• We are on our third generation of
wireless WANs – there was
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analog voice,
digital voice,
and now digital voice and data.
• Distances are much greater than LANs,
but bandwidth is much lower.
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Wireless Networks
(a) Individual mobile computers
(b) A flying LAN
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Home Network Categories.
Many devices are capable of being networked:
 Computers (desktop PC, PDA, shared peripherals)
 Entertainment (TV, DVD, VCR, camera, stereo, MP3)
 Telecomm (telephone, cell phone, intercom, fax)
 Appliances (microwave, fridge, clock, furnace, airco,
lights)
 Telemetry (utility meter, burglar alarm, thermostat,
babycam).
• Many of us have them already – multiple computers all
connected.
• What about connections to phones, entertainment systems,
appliances and other devices?
• How practical is a home network?
• Will people pay so that their toaster can talk to their fridge?
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Home Network Categories
Requirements:
1. Easy to install, manage
2. Foolproof in operation
3. High performance to connect
multimedia devices
4. Low cost
5. Expand the network gradually
6. Secure and reliable
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Internetworks
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Replace the subnet by a WAN we’ll
get Internetworks.
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The subnet consists of routers and transmission
lines.
A WAN contains both routers and hosts
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Internetworks
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A collection of interconnected networks is
called an internetwork or internet.
Connections are usually made through
gateways that can provide the translation
between the two different technologies.
An internetwork is formed when distinct
networks are connected ex: a LAN and a WAN
or two LANs are connected
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TEST YOUR UNDERSTANDING
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Q 1- 10 ? p.24
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1.3 The Internet
•The Internet has revolutionized many aspects of our
daily lives.
•It has affected the way we do business as well as the
way we spend our leisure time.
•The Internet is a communication system that has
brought a wealth of information to our fingertips and
organized it for our use.
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1.3 The Internet
•A Brief History
•The Internet Today
•When 2 or more networks are connected, they become an internetwork, or
internet.
•An internet is a network of networks.
•An "internet" (lower case i) is any computers connected to each other (a
network), and are not part of the Internet unless the use TCP/IP protocols.
•The Internet (upper case) is a collaboration of more
than 100s thousands interconnected networks.
INTERNET (Upper case I) The vast collection of interconnected networks that all use the TCP/IP
protocols and that evolved from the ARPANET of the late 60’s and early 70’s.
•The Internet is a structured, organized collection of many separate
networks.
•TCP/IP is the protocol suite for the Internet.
•An "intranet" is a private network inside a company or organization that uses the same kinds of
software that you would find on the public Internet, but that is only for internal use. An
intranet may be on the Internet or may simply be a network
.
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What is the World Wide Web?
From the Free Online Dictionary of Computing, we get this definition from its entry
for WWW:
"An
Internet client-server hypertext distributed
information retrieval system." The Web is
not a network. The Web is not the Internet itself. The Web is not a
proprietary system like AOL. Instead the Web is a system of clients (Web
browsers) and servers that uses the Internet for its data exchange.

On the WWW everything (documents, menus, indices) is represented to
the user as a hypertext object in HTML format. Hypertext links
refer to other documents by their URLs.
 These can refer to local or remote resources accessible via FTP,
Gopher, Telnet or news, as well as those available via the http
protocol used to transfer hypertext documents.
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What is the World Wide Web?
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The client program (known as a browser), e.g. NCSA
Mosaic, Netscape Navigator, runs on the user's computer
and
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two basic navigation
operations:
provides
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to follow a link or
to send a query to a server.
A variety of client and server software is freely
available.
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A brief history of the Internet.
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• ARPANET (50s and 60s, some universities)
• NSFNET (late 70s, all universities)
• TCP/IP (invention ’74) became the official protocol in 1983.
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When NSFNET and the ARPANET were connected, the growth
became exponential
Many regional networks (Canada, Europe, the Pacific) joined up
In mid-80s people began viewing the collection of networks as the
Internet
The glue that holds the Internet together is the TCP/IP reference
model and TCP/IP protocol stack
• ANS (Advanced Networks and Service) by MERIT, MCI, and IBM
took over NSFNET in 1990 and form ANSNET
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•
ANSNET
sold to American Online in 1995.
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The ARPANET
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Growth of the ARPANET (a) December 1969. (b) July 1970.
(c) March 1971. (d) April 1972. (e) September 1972.
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Figure 1.13 Hierarchical organization of the Internet
•End users to be connected
use the services
of Internet Service
Provider (ISP)
NAP = Network Access Point
to the Internet Backbone
in major cities,
is the complex switching stations.
Speed: up to 600 Mbps
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Figure 1.13
Internet today
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There are local, regional, national, and international Internet service providers (ISPs).
NAP = Network Access Point
to the Internet Backbone
in major cities,
is the complex switching stations.
Speed: up to 600 Mbps
•End users to be connected use the services
of Internet Service Provider (ISP)
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EO - End Office
PSTN – Public Switching Telephony Network
PBX
– Private
Exchange Switch
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1.4 Protocols and Standards
•Protocols
•Set of rules that governs data
communication
•Key elements:
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•Syntax
•Structure or format – order in which they are
presented
•Semantics
•Meaning of each section of bits
•Timing
•What data and how fast they can be sent
not to overload a receiver.
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1.4 Standards
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A standard provides a model for
development that enables a product to
work regardless of the individual
manufacturer
Standards are essential in:
i. Creating competitive markets for
equipment manufacturers
ii. Guaranteeing national and international
interoperability and compatibility
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1.4 Standards Categories
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De Facto (by fact) standards
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Proprietary
Nonproprietary
De Jure (by law) standards
read: dyzuri
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1.4 Protocols and Standards
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Standards Organizations
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The ISO,
ITU-T (previously CCITT),
ANSI,
IEEE, and
EIA
are some of the organizations involved in
standards creation.
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1.4 Protocols and Standards
Forum
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Consist of representatives from interested
corporations
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Present their conclusions to the standards
bodies
Facilitate standardization process
Frame Relay Forum
ATM Forum and Consortium
Internet Society (ISOC) and Internet
Engineering Task Force (IETF)
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1.4 Protocols and Standards
Forum
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are special-interest groups (work with
universities and users), that evaluate and
standardize new technologies.
Internet Standards
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Is a thoroughly tested specification that is useful
to and adhered to by those who work with the
Internet
First an Internet draft is published as a Request
For Comment (RFC)
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is an idea or concept that is a precursor to an Internet
standard.
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1.4 Protocols and Standards
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ISO (International Standards Organization) 1946 – vast
number of subjects
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89 countries
13000 standards
ISO is a member of ITU-T
Documents are:
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ANSI (American National Standards Institute)
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Private, nongovernmental, nonprofit organization
NIST (National Institute of Standards and Technology) – a
part of the US Dept of Commerce
IEEE (Institute of Electrical and Electronics Engineering)
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Draft
Draft International
International Standard
Largest professional organization in the world
ITU-T International Telecommunications Union Telecommunications Standardization Sector (former CCITT) –
3000 recommendations
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1.4 Protocols and Standards
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ISO
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ISO 8877—Interface in Integrated Services
Digital Network (ISDN)
ISO 3309—HDLC frame structure
ISO 8028—X.25 packet level protocol
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1.4 Protocols and Standards
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ITU-T
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V.32: Defines data transmission over
phone lines
X.25: Defines transmission over public
digital networks
I.430: Define physical layer specifications for
an interface
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1.4 Protocols and Standards
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ANSI
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X3. 23-1985 Programming language COBOL
SONET Synchronous Optical Network
ISDN Integrated Services Digital Network
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1.4 Protocols and Standards
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IEEE
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IEEE 802.3: CSMA/CD LAN
IEEE 802.4: Token Bus LAN
IEEE 802.5: Token Ring LAN
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1.4 Protocols and Standards
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EIA
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EIA-232: A 25-pin interface standard
EIA-449: Specifies a 37-pin connector and a
9-pin connector
EIA-530: Defines a 25-pin connector
1.4 Regulatory Agencies
Federal Communication Commission (FCC)
 Authority for interstate and international
traffic
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Reviews communication services and prices
Reviews technical specs of communication
hardware
Assigns carrier frequencies for radio and
television
Public Utility Commission (PUC)
 Authority for intrastate traffic
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IP Address
Download and install free utility. Run it from Start => All Programs =>
VisualRoute 2009 – Lite Edition or from Internet Explorer under Tools
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IP Address
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Each device connected to the Internet
has a unique numeric IP address.
These addresses consist of a set of four
groups of numbers, called octets.
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66.94.234.13 will get you Yahoo!
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Use
ping 66.94.234.13
 ping yahoo.com
 tracert yahoo.com
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as exercises
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Your IP can be found here http://myip.dk/
exercises