Networking Basics

1
Networking Basics

• Module 2

2
Table of Contents

• Networking
• Terminology

Go There!
Bandwidth
Go There!
Networking Models
Go There!
3
Networking Terminology
Table of Contents
4
Data networks 2.1.1

• Mainframe computers were connected to terminals
• Did not share information with microcomputers
• Microcomputers were not connected to mainframes
• Could not share information between
  microcomputers
• Sneaker net was developed
• Copy data onto a floppy disk and carry disk to
  the other user
• Not efficient if you modified the file
• Not cost effective

5
Networks were developed

• Businesses needed a solution that would
  successfully address the following three
  problems
• How to avoid duplication of equipment and
  resources
• How to communicate efficiently
• How to set up and manage a network
• 1980s tremendous expansion
• Problem
• each company developed its own software and
  hardware specifications
• old equipment had to be replaced with each
  upgrade

6
Creation of LANs

• Solution
• Each department of the company is a kind of
  electronic island
• As the use of computers in businesses grew, it
  soon became obvious that even LANs were not
  sufficient
• What was needed was a way for information to move
  efficiently and quickly, not only within a
  company, but also from one business to another.
  
• The solution was the creation of
  metropolitan-area networks (MANs) and wide-area
  networks (WANs).

7
Network history 2.1.2

• 1940s- computers were electromechanical devices
• 1950s- mainframe computers used punch card
  programs for large institutions
• 1960s-mainframes with terminals had integrated
  circuits were widely used
• 1970s- minicomputers introduced like the Apple
  Computer Company
• 1981- IBM introduced its first personal
  computer, now Mac IBM PC were widely used

8

• Mid 1980s- standalone computers shared files by
  modems connected to other computers
• Starting in the 60s through 90s Department of
  Defense (DoD) developed large, reliable,
  wide-area networks (WAN) for military
  scientific reasons
• The DoDs WAN eventually became the Internet

9
Networking devices 2.1.3

• Equipment that connects directly to a network
  segment is referred to as a device
• End user devices are
• Computers
• Printers
• Scanners
• Other devices that provide services directly to
  the user

10

• Hosts- End-user devices that provide users with a
  connection to the network
• Allow users to share, create, and obtain
  information
• Host devices are physically connected to the
  network media using a network interface card
  (NIC)

11

• NIC is a printed circuit board that fits into the
  expansion slot of a bus on a computer
  motherboard, or it can be a peripheral device.
• It is also called a network adapter
• Each individual NIC carries a unique code, called
  a Media Access Control (MAC) address.
• This address is used to control data
  communication for the host on the network.

12

• Network devices provide transport for the data
  that needs to be transferred between end-user
  devices
• Network devices provide extension of cable
  connections, concentration of connections,
  conversion of data formats, and management of
  data transfers
• Examples of devices that perform these functions
  are repeaters, hubs, bridges, switches, and
  routers

13
Repeater

• network device used to regenerate a signal
• Regenerate analog or digital signals distorted by
  transmission loss due to attenuation
• Does not perform intelligent routing like a
  bridge or router.

14
Hubs- Multiport repeater

• Hubs concentrate connections
• Hubs take a group of hosts and allow the network
  to see them as a single unit
• This is done passively (without any other effect
  on the data transmission)
• Active hubs not only concentrate hosts, but they
  also regenerate signals.

15
Bridges- Forward Filter Mac addresses

• Bridges convert network transmission data formats
  as well as perform basic data transmission
  management
• Provide connections between LANs
• Perform a check on the data to determine whether
  it should cross the bridge or not
• This makes each part of the network more
  efficient

16
Switches- multi port bridges

• Workgroup switches add more intelligence to data
  transfer management
• Not only can they determine whether data should
  remain on a LAN or not, but they can transfer the
  data only to the connection that needs that data
• Another difference between a bridge and switch is
  that a switch does not convert data transmission
  formats

17
Routers

• Routers have all the capabilities that bridges
  and switches have.
• Routers can regenerate signals, concentrate
  multiple connections, convert data transmission
  formats, and manage data transfers.
• They can also connect to a WAN, which allows them
  to connect LANs that are separated by great
  distances.
• None of the other devices can provide this type
  of connection.

18
Network topology 2.1.4

• Network topology defines the structure of the
  network
• One part of the topology definition is the
  physical topology, which is the actual layout of
  the wire or media
• The other part is the logical topology, which
  defines how the media is accessed by the hosts
  for sending data

19
Physical topology

• Bus topology
• Bus topology uses a single backbone cable that is
  terminated at both ends
• All the hosts connect directly to this backbone.

20

• Ring topology
• A ring topology connects one host to the next and
  the last host to the first
• This creates a physical ring of cable

21

• Star topology
• A star topology connects all cables to a central
  point of concentration.
• Extended Star topology  
• An extended star topology links individual stars
  together by connecting the hubs and/or switches.
• This topology can extend the scope and coverage
  of the network

22

• Hierarchical topology
• Similar to an extended star
• However, instead of linking the hubs and/or
  switches together, the system is linked to a
  computer that controls the traffic on the
  topology

23

• Mesh topology
• Implemented to provide as much protection as
  possible from interruption of service
• each host has its own connections to all other
  hosts
• Although the Internet has multiple paths to any
  one location, it does not adopt the full mesh
  topology
• The use of a mesh topology in the networked
  control systems of a nuclear power plant would be
  an excellent example

24
Logical topology

• Logical topology of a network is how the hosts
  communicate across the medium
• Two most common types of logical topologies
• Broadcast- ethernet
• Each host sends its data to all other hosts on
  the network medium
• 1st come, 1st serve
• token passing- Token Ring FDDI (Fiber
  Distributed Data Interface)

25
Token passing FDDI

• Token passing controls network access by passing
  an electronic token sequentially to each host.
• When a host receives the token, that host can
  send data on the network.
• If the host has no data to send, it passes the
  token to the next host and the process repeats
  itself.

26
Network protocols 2.1.5

• A protocol is a formal description of a set of
  rules and conventions that govern a particular
  aspect of how devices on a network communicate.
• Protocols determine the format, timing,
  sequencing, and error control in data
  communication.
• Without protocols, the computer cannot make or
  rebuild the stream of incoming bits from another
  computer into the original format

27
Protocols determine

• How the physical network is built
• How computers connect to the network
• How the data is formatted for transmission
• How that data is sent
• How to deal with errors
• Organizations that maintain these network rules
• Institute of Electrical and Electronic Engineers
  (IEEE)
• American National Standards Institute (ANSI)
• Telecommunications Industry Association (TIA)
• Electronic Industries Alliance (EIA)
• International Telecommunications Union (ITU),
  formerly known as the Comité Consultatif
  International Téléphonique et Télégraphique
  (CCITT)

28
Local Area Networks 2.1.6

• LANs consist of the following components
• Computers
• Network interface cards
• Peripheral devices
• Networking media
• Network devices

29
LANs

• Operate within a limited geographic area
• Allow multi-access to high-bandwidth media
• Control the network privately under local
  administration
• Provide full-time connectivity to local services
• Connect physically adjacent devices

30
Common LAN technologies

• Ethernet
• Token Ring
• FDDI

31
Wide Area Networks 2.1.7

• Operate over a large geographical area
• Allow access over serial interfaces operating at
  lower speeds
• Provide full-time and part-time connectivity
• Connect devices separated over wide, even global
  areas
• Provide e-mail, World Wide Web, file transfer,
  and e-commerce services

32
WANs technologies

• Modems
• Integrated Services Digital Network (ISDN)
• Digital Subscriber Line (DSL)
• Frame Relay
• US (T) and Europe (E) Carrier Series T1, E1,
  T3, E3
• Synchronous Optical Network (SONET)

33
Metropolitan area networks 2.1.8

• MAN- network that spans a metropolitan area such
  as a city or suburban area.
• usually consists of two or more LANs in a common
  geographic area.
• Typically, a service provider is used to connect
  two or more LAN sites using private communication
  lines or optical services.
• MAN can also be created using wireless bridge
  technology by beaming signals across public areas
  

34
Storage area networks 2.1.9

• SAN is a dedicated, high-performance network used
  to move data between servers and storage
  resources.
• Because it is a separate, dedicated network, it
  avoids any traffic conflict between clients and
  servers

35
SANs offer the following features

• Performance SANs enable concurrent access of
  disk or tape arrays by two or more servers at
  high speeds, providing enhanced system
  performance.
• Availability SANs have disaster tolerance built
  in, because data can be mirrored using a SAN up
  to 10 kilometers (km) or 6.2 miles away.
• Scalability Like a LAN/WAN, it can use a
  variety of technologies. This allows easy
  relocation of backup data, operations, file
  migration, and data replication between systems.

36
Virtual private network 2.1.10

• A VPN is a private network that is constructed
  within a public network infrastructure such as
  the global Internet
• Using VPN, a telecommuter can access the network
  of the company headquarters through the Internet
  by building a secure tunnel between the
  telecommuters PC and a VPN router in the
  headquarters.

37
Benefits of VPNs 2.1.11

• Offers secure, reliable connectivity over a
  shared public network infrastructure
• Same security management policies as a private
  network
• Cost-effective for point-to-point connection
  between remote users enterprise customers
  network

38
3 main types of VPNs

• Access VPNs
• Intranet VPNs
• Extranet VPNs

39
Access VPNs

• Access VPNs provide remote access to a mobile
  worker and small office/home office (SOHO) to the
  headquarters of the Intranet or Extranet over a
  shared infrastructure
• Access VPNs use analog, dialup, ISDN, digital
  subscriber line (DSL), mobile IP, and cable
  technologies to securely connect mobile users,
  telecommuters, and branch offices

40
Intranet VPNs

• Intranet VPNs link regional and remote offices to
  the headquarters of the internal network over a
  shared infrastructure using dedicated connections
  
• Intranet VPNs differ from Extranet VPNs in that
  they allow access only to the employees of the
  enterprise

41
Extranet VPNs

• Extranet VPNs link business partners to the
  headquarters of the network over a shared
  infrastructure using dedicated connections
• Extranet VPNs differ from Intranet VPNs in that
  they allow access to users outside the enterprise
  

42
Intranets

• One common configuration of a LAN is an Intranet
• Intranet Web servers - the public must have the
  proper permissions and passwords to access the
  Intranet of an organization
• Designed to permit access by users who have
  access privileges to the internal LAN of the
  organization
• Example- your college or business intranet
• Web servers are installed in the network to
  enable communication or sharing of files

43
Extranets

• Extranets refer to applications and services that
  are Intranet based, and use extended, secure
  access to external users or enterprises
• This access is usually accomplished through
  passwords, user IDs, and other application-level
  security.
• Extranet is the extension of two or more Intranet
  strategies with a secure interaction between
  participant enterprises and their respective
  intranets.

44
Bandwidth
Table of Contents
45
Importance of bandwidth 2.2.1

• Bandwidth is defined as the amount of information
  that can flow through a network connection in a
  given period of time
• Why bandwidth is important
• Limited by physics technology
• Not free
• Requirements are growing at a rapid rate
• Critical to network performance

46
Analogies 2.2.2

• Bandwidth is like the width of a pipe
• Bandwidth is also like the number of lanes on a
  highway

47
Measurement 2.2.3

• Bandwidth is the measure of how much information,
  or bits, can flow from one place to another in a
  given amount of time, or seconds
• Can be measured in
• Bits per second (bps)
• Thousands of bits per second (kbps)
• Millions of bits per second (Mbps)
• Billions of bits per second (Gbps)
• Trillions of bits per second (Tbps)

48
Limitations 2.2.4

• Bandwidth varies depending upon the type of media
  as well as the LAN and WAN technologies used
• Signals travel through twisted-pair copper wire,
  coaxial cable, optical fiber, and air

49
Throughput 2.2.5

• Bandwidth is the measure of the amount of
  information that can move through the network in
  a given period of time
• Throughput refers to actual measured bandwidth,
  at a specific time of day, using specific
  Internet routes, and while a specific set of data
  is transmitted on the network

50
Factors that determine throughput

• Internetworking devices
• Type of data being transferred
• Network topology
• Number of users on the network
• User computer
• Server computer
• Power conditions

51
Data transfer calculation 2.2.6

• Network designers administrators make decisions
  regarding bandwidth
• Should they increase size of the WAN connection
  to accommodate a new database
• LAN backbone, does it have sufficient bandwidth
  for streaming-videos

52
Digital versus analog 2.2.7

• Radio, television, and telephone transmissions
  have, until recently, been sent through the air
  and over wires using electromagnetic waves
• waves are called analog because they have the
  same shapes as the light and sound waves produced
  by the transmitters
• Measurement-
• Hertz (Hz), or cycles per second
• Kilohertz (KHz)
• Megahertz (MHz)
• Gigahertz (GHz)

53
Disadvantages of Analog signals

• Can not carry as much information as digital
• Smaller band range
• If analog bandwidth not available, signal can not
  be sent

54
Networking Models
Table of Contents
55
Layers to analyze problems 2.3.1
56
Layers to analyze problems 2.3.1
57
Layers to analyze problems 2.3.1
58
Layers to describe data comm 2.3.2

• In order for data packets to travel from a source
  to a destination on a network, it is important
  that all the devices on the network speak the
  same language or protocol
• A protocol is a set of rules that make
  communication on a network more efficient
• For example, while flying an airplane, pilots
  obey very specific rules for communication with
  other airplanes and with air traffic control

59
OSI model 2.3.3

• 1980s brought tremendous growth to networks
• Companies experienced problems with rapid
  expansion
• Problem how to exchange information between
  proprietary software and hardware
• ISO (International Organization for
  Standardization) researched different models
• ISO created a network model that helps vendors
  create networks that are compatible with other
  networks
• 1984- OSI (Open Systems Interconnection) released

60
OSI model Benefits

• Reduces complexity
• Standardizes interfaces
• Facilitates modular engineering
• Ensures interoperable technology
• Accelerates evolution
• Simplifies teaching and learning

61
OSI layers 2.3.4

• OSI reference model is a framework that is used
  to understand how information travels throughout
  a network
• OSI reference model explains how packets travel
  through the various layers to another device on a
  network, even if the sender and destination have
  different types of network media
• there are seven numbered layers

62
Advantages of layers

• It breaks network communication into smaller,
  more manageable parts.
• It standardizes network components to allow
  multiple vendor development and support.
• It allows different types of network hardware and
  software to communicate with each other.
• It prevents changes in one layer from affecting
  other layers.
• It divides network communication into smaller
  parts to make learning it easier to understand

63
OSI Layers
64
Peer-to-peer comm. 2.3.5

• In order for data to travel from the source to
  the destination, each layer of the OSI model at
  the source must communicate with its peer layer
  at the destination
• This form of communication is referred to as
  peer-to-peer
• During this process, the protocols of each layer
  exchange information, called protocol data units
  (PDUs).

65
Data Encapsulation Process

• Data packets on a network originate at a source
  and then travel to a destination
• Each layer depends on the service function of the
  OSI layer below it.
• To provide this service, the lower layer uses
  encapsulation to put the PDU from the upper layer
  into its data field then it adds whatever
  headers and trailers the layer needs to perform
  its function
• Next, as the data moves down through the layers
  of the OSI model, additional headers and trailers
  are added

66
Transport layer encapsulation

• After Layers 7, 6, and 5 have added their
  information, Layer 4 adds more information. This
  grouping of data, the Layer 4 PDU, is called a
  segment

67
Network Layer encapsulation

• The network layer provides a service to the
  transport layer, and the transport layer presents
  data to the internetwork subsystem.
• The network layer has the task of moving the data
  through the internetwork.

68
Network layer encapsulation

• It accomplishes this task by encapsulating the
  data and attaching a header creating a packet
  (the Layer 3 PDU).
• The header contains information required to
  complete the transfer, such as source and
  destination logical addresses

69
Data Link layer encapsulation

• The data link layer provides a service to the
  network layer. It encapsulates the network layer
  information in a frame (the Layer 2 PDU).
• The frame header contains information (for
  example, physical addresses) required to complete
  the data link functions.
• The data link layer provides a service to the
  network layer by encapsulating the network layer
  information in a frame

70
Physical layer encapsulation

• The physical layer also provides a service to the
  data link layer. The physical layer encodes the
  data link frame into a pattern of 1s and 0s
  (bits) for transmission on the medium (usually a
  wire) at Layer 1.

71
TCP/IP model 2.3.6

• historical and technical standard of the Internet
  is the TCP/IP model
• The U.S. Department of Defense (DoD) created the
  TCP/IP reference model, because it wanted to
  design a network that could survive any
  conditions, including a nuclear war.
• In a world connected by different types of
  communication media such as copper wires,
  microwaves, optical fibers and satellite links,
  the DoD wanted transmission of packets every time
  and under any conditions
• TCP/IP was developed as an open standard.

72
(No Transcript)
73
(No Transcript)
74
Encapsulation process

• Data
• Segments
• Packets
• Frames
• Bits

75
Table of Contents
End Slide Show