Alfredo Digrillioni:

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• Alfredo Digrillioni
• -Introduction to Networking
• -OSI model
• Jalal Pirzada
• -Topology and Access
• -Designs and software
• Aymin Matri
• -Protocols
• -IP Addressing
• Stephen Kurtz
• -Subnetting
• -Intranet

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FUNDAMENTALS OF NETWORKING

• NETWORK
• INTERCONNECTION OF COMPUTERS LINKED TOGETHER
  USING A VARIETY OF DIFFERENT CONECTING MEANS.
• COMPUTERS ARE INTERCONNECTED FOR DIFFERENT
  PURPOSES.
• REASONG FOR NETWORKING
• TO SHARE RESOURCES (FILES, PRINTERS, MODEMS, FAX
  MACHINES)
• TO SHARE APPLICATIONS SOFTWARE
• TO INCREASE PRODUCTIVITY (TO MAKE EASIER TO SHARE
  DATA AMONGST USERS)
• MOST COMMON TYPES OF NETWORKS
• LANs (LOCAL-AREA NETWORKS)
• WANs (WIDE-AREA NETWORKS)? COMPUTER ARE FARTHER
  APART AND ARE CONNECTED VIA TELEPHONE/COMMUNICATIO
  N LINES, RADIO WAVES, OR OTHER MEANS OF
  CONNECTION.
• THE INTERNET IS AN EXAMPLE OF THIS TYPE OF
  NETWORKING.

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BRIEF HISTORY OF NETWORKING

• ARPANET (YEAR 1969)? WAS AN EXPERIMENTAL NETWORK
  CONNECTING THE MAINFRAME COMPUTERS OF
  UNIVERSITIES AND OTHER FEDERAL CONTRACTORS.
• THIS PROJECT WAS FUNDED BY ARPA (ADVANCED
  RESEARCH PROJECT AGENCY OF THE U.S. DEPARTMENT OF
  DEFENSE)
• INTRANETS? EXPANSION OF CORPORATE GOVERNMENT
  (PRIVATE) NETWORKS / NO ACCESS TO THE GENERAL
  PUBLIC.
• INTERNET? NETWORK OF NETWORKS / GLOBAL
• ACCESIBLE TO EVERYBODY
• INTERNATIONAL STANDARDS IN NETWORKING
• IN 1983/1984 THE ISO (INTERNATIONAL STANDARDS
  ORGANIZATION)? ADOPTED A CODIFICATION OF THE
  IDEAL NETWORK PROTOCOL STACK IN A SCHEME CALLED
  OSI (OPEN SYSTEM INTERFACE REFERENCE MODEL OR
  OPEN SYSTEM INTERCONNECTION MODEL)
• THE MODEL ALLOWS THE SENDING AND RECEIVING OF
  DATA BETWEEN TWO DISSIMILAR COMPUTERS, USING A
  LAYER APPROACH (EACH LAYER IS RESPONSIBLE FOR
  PERFORMING CERTAIN FUNCTIONS).

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OSI MODEL

• COMPUTERS CAN TRANSFER DATA BETWEEN THEMSELVES,
  WITHOUT RESTRICTIONS ON THE TYPE OF OF HARDWARE
  OR SOFTWARE USED.
• DIVIDES NETWORKING SOFTWARE INTO A VERTICAL
  SEVEN-LAYER STACK, IN WHICH EACH LAYER HAS A
  DISTINCT FUNCTION.
• MESSAGES BETWEEN TWO CONNECTED MACHINES ARE SENT
  DOWN THE STACK OF THE SENDING MACHINE, ACROSS THE
  NETWORK, AND UP THE STACK OF THE RECEIVING
  MACHINE.
• WHY THE LAYER APPROACH ?
• SENDING DATA FROM ONE COMPUTER TO ANOTHER
  REQUIRES MANY DIFFERENT TASKS TO BE PERFORMED.
• DIVIDING THOSE FUNCTIONS INTO SEPARATE LAYERS
  MAKES WRITING THE RESPECTIVE SOFTWARE MUCH EASIER

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• OSI MODEL - SEVEN LAYERS
• LAYER 7 APPLICATION LAYER
• PROVIDES APPLICATIONS WITH ACCESS TO NETWORK
  SERVICES.
• THE PROGRAMS WHICH USE SERVICES OF THE NETWORK
  RESIDE IN THIS LAYER.
• LAYER 6 PRESENTATION LAYER
• DETERMINES THE FORMAT USED TO EXCHANGE DATA
  AMONG NETWORKED COMPUTERS.
• IT FORMATS DATA FOR THE PURPOSE OF DISPLAY OR
  PRINTING.
• LAYER 5 SESSION LAYER
• ALLOWS TWO APPLICATIONS TO ESTABLISH, USE AND
  DISCONNECT A CONNECTION BETWEEN (CALLED A
  SESSION).
• PROVIDES FOR NAME RECOGNITION AND ADDITIONAL
  FUNCTIONS LIKE SECURITY WHICH ARE NEEDED TO ALLOW
  APPLICATIONS TO COMMUNICATE OVER THE NETWORK.

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• LAYER 4 TRANSPORT LAYER
• ENSURES THAT DATA IS DELIVERED ERROR FREE, IN
  SEQUENCE AND WITH NO LOSS, DUPLICATIONS OR
  CORRUPTION.
• THIS LAYER ALSO REPACKAGES DATA BY ASSEMBLING
  LONG MESSAGES INTO LOTS OF SMALLER MESSAGES FOR
  SENDING, AND REPACKAGING THE SMALLER MESSAGES
  INTO THE ORIGINAL LARGER MESSAGE AT THE RECEIVING
  END.
• LAYER 3 NETWORK LAYER
• THIS LAYER IS RESPONSIBLE FOR ADDRESSING
  MESSAGES AND DATA SO THEY ARE SENT TO THE CORRECT
  DESTINATION, AND FOR TRANSLATING LOGICAL
  ADDRESSES AND NAMES INTO PHYSICAL ADDRESSES.
• THIS LAYER IS ALSO RESPONSIBLE FOR FINDING A
  PATH THROUGH THE NETWORK TO THE DESTINATION
  COMPUTER.

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• LAYER 2 DATA-LINK LAYER
• THIS LAYER TAKES THE DATA FRAMES OR MESSAGES
  FROM THE NETWORK LAYER AND PROVIDES FOR THEIR
  ACTUAL TRANSMISSION.
• IT ALSO PROVIDES ERROR-FREE DELIVERY OF DATA
  BETWEEN THE TWO COMPUTERS BY USING THE PHYSICAL
  LAYER IT PACKAGES THE DATA FROM THE NETWORK
  LAYER INTO A FRAME WHICH INCLUDES ERROR DETECTION
  INFORMATION.
• AT THE RECEIVING COMPUTER, THE DATA-LINK LAYER
  READS THE INCOMING FRAME, AND GENERATES ITS OWN
  ERROR DETECTION INFORMATION BASED ON THE RECEIVED
  FRAMED DATA.
• AFTER RECEIVING ALL OF THE FRAME, IT COMPARES
  ITS ERROR DETECTION VALUE WITH THAT OF THE
  INCOMING FRAMES, AND IF
• THEY MATCH, THE FRAME HAS BEEN RECEIVED
  CORRECTLY.

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• LAYER 1 PHYSICAL LAYER
• CONTROLS THE TRANSMISSION OF THE ACTUAL DATA
  ONTO THE NETWORK CABLE.
• IT DEFINES THE PHYSICAL COMMUNICATION MEDIA
  (TYPE OF CABLE, FREQUENCY, TERMINATIONS, ETC.).

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Network Computers are connected to each other
and to other devices (wired or wireless)
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Major Types of Networks

• -Local Area Network (LAN) A network that
  connects computers that are close to each other,
  usually in the same building, linked by a cable.
• -Wide Area Network (WAN) A network in which
  computers are connected to each other over a long
  distance, using telephone lines and satellite
  communications.
• -largest WAN is the Internet
• -two or more LANs connected together
• -Metropolitan Area Networks (MAN) A data network
  designed for a town or city.
• -LAN, WAN, MAN uses Topology, Access (speed),
  and Designs but vary due to size location
• -Future Wireless Networking (Blue Tooth) or
  Networking by Electrical Outlet

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Basic Topologies

• The configuration of a network the ways
  computers are interconnected. Common network
  topologies are
• Bus
• Star
• Ring
• Mesh

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Bus Topology Single cable connects all the
computers in a line

• Pros
• -Simple
• -One Wire or Cable
• Cons
• -Single point of failure can stop the entire
  network
• -Slow and not efficient

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Star Topology Computers are connected to hub by
a cable

• Pros
• -One computer fails, the remainder function
  normally
• Cons
• -If the hub fails, the entire network fails

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Ring Topology Computers are connected to a cable
that forms a circle around a central location

• Pros
• -Each computer acts as a repeater, regenerating
  the signal
• -Handles high traffic environments better than a
  bus topology
• Cons
• -Only one computer at time can send data on a
  single token ring
• -More expensive

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Mesh Topology Computers on the network are
connected to every other computer by cable

• Pros
• -Backup capabilities, one cable fails info can
  still be passed
• -Multiple LANs can be connected in a Mesh by
  leased telephone lines, or fiber optic lines
• Cons
• -Redundant paths require more cabling, hence
  expensive

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Accessing (Speed) The Network

• Ethernet
• Token Ring
• ATM (Asynchronous Transfer Mode)
• FDDI (Fiber Distributed Data Interface)

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• Ethernet -The most popular type of local area
  network, which sends its communications through
  radio frequency signals carried by a coaxial
  cable.
• -Each computer checks to see if another computer
  is transmitting and waits its turn to transmit.
• -If two computers accidentally transmit at the
  same time and their messages collide, they wait
  and send again in turn.
• Transfer Speed 10mbps to 1Gibabit mbps

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• Token Ring -A local area network in which
  computers are configured in a ring, and a message
  called a token is passed from station to station.
  
• -The token is used to avoid conflicts in
  transmission a machine can only transmit
  messages while it holds the token.
• Transfer Speed 4-16mbps for all cable types

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• ATM 1. Asynchronous Transfer Mode, a network
  technology that enables the transmission of data,
  voice, audio, video, and frame relay traffic in
  real time.
• 2. Automatic Teller Machine, a bank terminal
  that lets customers deposit, withdraw cash, and
  perform other transactions electronically.
• Transfer Speed FiberOptic 155 to 622mbps

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• FDDI Fiber Distributed Data Interface. An ANSI
  standard for 100 Mbit/s data transmission through
  fiber optic cable, in a token ring setup.
• Many local area networks can be linked together
  with a backbone that uses FDDI.
• Transfer Speed FiberOptic 155 to 622mbps

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Network Designs

• Workgroup
• Client/Server
• Domain Based
• Directory Based

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Workgroup Two or more computer users working
together on a project, sharing data and files by
means of a network.
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• Client/Server
• An architecture in which one computer can get
  information from another.
• The client is the computer that asks for access
  to data, software, or services.
• The server, which can be anything from a personal
  computer to a mainframe, supplies the requested
  data or services for the client.

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Software

• Network Operating System
• -Windows NT or 2000
• -Novell Netware

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Protocols
Protocol It is a set of rules that governs data
communication. A protocols defines what is
communicated, how it is communicated and when it
is communicated. The key elements of a protocols
are Syntax, Semantics and Timing.
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Standards

• Standards are essential in guaranteeing national
  and international operability of data and
  telecommunication technology.
• They are developed through cooperation of
  standard creation committees, forums and
  government agencies.

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Standards Creation Committees

• International Standards Organization (ISO)
• International Telecommunication Union-
  Telecommunication Standards Sector (ITU-T)
• American National Standards Institute (ANSI)
• Institute of Electrical and Electronic Engineers
  (IEEE)
• Electronic Industry Association (EIA)

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IP Addressing

• An IP (Internet Protocols) address is a 32-bit
  address that uniquely defines a host or a router
  on the Internet.
• The IP addresses are unique in the sense that two
  devices can never have the same address, however
  a device can have more than one address.

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To make the 32-bit form more compact and easier
to read, Internet addresses are usually written
in a decimal form with decimal points separating
the byte 10000000 00001011 00000011
00011111
128. 11. 3. 31
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Each IP address is a pair (Netid and Hostid)
where netid identifies a network and the hostid
identifies a host on that network.
Netid Hostid
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IP Address classes
There are five different IP Address classes
A,B,C,D and E, they are designed to cover the
need of different types of organizations. Class A
the first 8 bits (Octet) defines the netid and
the remaining 24 bits are used to define the
hostid. Class B Two Octets define the netid and
two defines the hostid. Class C Three octets
define the netid and one octet defines the
hostid Class D this class is for
multicasting. Class E This class is reserved by
the Internet for special use
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Determining the class of an Address
From
To Class A 0.0.0.0
127.255.255.255 Class B 128.0.0.0
191.255.255.255 Class C 192.0.0.0
223.255.255.255 Netid
Hostid Netid
Hostid Class D 224.0.0.0
239.255.255.255 Multicast Address
Multicast
Address Class E 240.0.0.0
255.255.255.255 Reserved
Reserved
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Subnetting

• A subnet is a part of a network, which has the
  same network address as other parts of the
  network but a unique subnet number.
• Within the ISO/OSI reference model, the layers
  below the transport layer are referred to as the
  subnet (network, data link, and physical layers).

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Why Subnet?

• Organization use of different physical media
  preservation of address space security
• Most common reason control network traffic In
  an Ethernet network, performance can be adversely
  affected under heavy traffic loads.

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Subnet Masking

• A subnet mask is used to determine what subnet an
  IP address belongs to.
• The subnet mask is the network address plus the
  bits reserved for identifying the subnetwork.

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Subnetting Example

• IP address 150.215.017.009
• Assuming this is part of a Class B network the
  first two numbers (150.215) represent the Class B
  network address, and the second two numbers
  (017.009) identify a particular host on this
  network.
• The IP address in binary format
• 10010110.11010111.00010001.00001001
• (Class B Network) (Host Address)

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Subnetting Example (contd)

• If the network is divided into 14 subnets,
  however, then the first 4 bits of the host
  address (0001) are reserved for the host.
• The subnet mask is the network address plus the
  bits reserved for identifying the subnetwork. By
  convention, the bits for the network address are
  all set to one, though it would it also work if
  the bits were set exactly as the network address.

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Subnetting Example (contd)Result
Subnet Mask 255.255.240.000 11111111.11111111.1
1110000.00000000 IP Address 150.215.017.009
10010110.11010111.00010001.00001001 Subnet
Address 150.215.016.000 10010110.
11010111.00010000.00000000
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Intranet

• A local area network (LAN) which may not be
  connected to the Internet, but which has some
  similar functions. Some organizations set up
  World Wide Web servers on their own internal
  networks so employees have access to the
  organizations Web documents.
• Architecture / Security issues

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Intranet Implementation

• Step 1 Define your needs
• Step 2 Choose your tool
• Step 3 Prepare and run the pilot
• Step 4 Prepare the rollout
• Step 5 Follow up closely and communicate

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Intranet Issues

• What does my business gain?
• How much will it cost now?
• How much will it cost later?
• Is it manageable?
• How does it fit into my existing systems?
• What kind of training will my developers and
  users need?
• Can I outsource my intranet?
• How will it affect productivity?
• How secure is it?
• How much time will it take to start one?