Connecting computers

1
Connecting computers

• Unit objectives
• Identify the components of a network
• Describe wired network connections
• Compare wireless networking standards
• Describe the different network architectures

2
Local area network (LAN)

• Located within a confined area
• Connected by wires or radio waves
• Devices communicate and share data and services
• Each device is called a node
• Computer
• Router
• Printer
• Sensing device
• Video camera
• Controller

continued
3
Local area network, continued

• Host is always a computer
• Can be connected to the Internet
• Direct cable connection
• Telephone link via modem

4
Example of a LAN
5
Basic types of networks

• Peer-to-peer network
• Usually consists of several client computers
  connected in a network for a simple file sharing
  and printer sharing in a small office or home
  office. Each computer has a network card
  connected to the network by a network cable or
  wireless media. All the communication is between
  the client computers.
• Client/server network
• Computers called servers hold data and provide a
  wealth of services that users can share . Most of
  the communication is between the clent computers
  and the servers.

6
Peer-to-peer model

• Each computer has same authority
• User decides to share resources
• User responsible for many administrative tasks
• Windows XP and Windows 2000 Professional support
  peer-to-peer
• Connect to form small LAN
• Wired
• Wireless

7
A peer-to-peer network
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Peer-to-peer authentication

• Each user enter valid user ID and password
• Authentication
• Validation
• Logging on
• Authenticated by the client operating system
• Local user account
• Exists only on a single computer

9
Local user account

• Collection of user information
• Includes
• User ID
• Password
• Permissions

10
Using a shared resource

• Click Start and choose My Computer
• Click My Network Places
• Click View workgroup computers
• Double-click the icon for the computer where the
  shared resource exists

11
Client/server model

• Network operating system manages network
  resources on LAN
• User accounts
• Printers
• File sharing
• Single network user ID and password
• Authenticate against the NOS (Network Operating
  System)
• Domain model another name for client/server
  model
• Administrator assigns permissions
• Server stores info in database

12
A client/server network
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Network client

• Client OS sends user ID and password to NOS on
  server
• Server verifies against database
• Uses network client software on client computer
• Network client communicates with NOS on server

14
The logon process

• The network client on the client computer
  displays a logon screen to the user
• The user enters his user ID and password at the
  logon screen and clicks OK
• The network client then sends this information to
  the NOS for authentication
• After the user ID and password have been
  authenticated, the user can gain access to the
  computer and to the network resources

15
Connections

• Established with a network adapter
• Type of connector varies with the type of network
  media
• NICs (Network Interface Cards) send and receive
  data
• Half-duplex Either sends or receive at a time
• Full-duplex Send and receive at the same time

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Network protocols

• Languages used for network communication
• Send data in packets
• Common protocols
• TCP/IP Routable, non-proprietary protocol thats
  the predominant Windows network protocol .
  Supported by all versions of Windows and most
  other non-Microsoft OS. It is also the protocol
  of the internet.
• IPX/SPX (Internetwork Packet Exchange/Internet
  Protocol Exchange) A routable, proprietary
  protocol that was native in the early versions of
  Novell NetWare. Later versions of Netware
  supported TCP/IP as the Native protocol. Windows
  can connect to IPX/SPX networks and NetWare
  servers using MS version of IPX/SPX called
  NWLink. To share files and printers on a Netware
  server, you must install the MS Client for
  NetWare server.
• AppleTalk -- A routable network protocol
  supported supported by Apple Macintosh computers.
  Windows NT and Windows 200 support Apple talk.
  Mac X(10.2 and later) supports TCP/IP and can
  connect to windows networks without requiring
  apple Talk support.
• NetBEUI Non routable, proprietary and supported
  under Windows 9x/me. Uses network Basic
  Input/Output System (NetBIOS). No settings to
  configure.

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Route Mechanism
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UTP and STP

• Ethernet network
• Unsheilded twisted pair (UTP)
• Shielded twisted pair (STP)
• UTP
• Cat3 - 10 Mbps (about 2 or 3 twists per foot)
• Cat5 - 100 Mbps (range of 20 twists per foot)
• Cat5e - 1 Gbps (range of 20 twists per foot)
• Cat6 up to 2.5 Gbps (range of 20 twists per
  foot) use higher quality material

19
Cat5 installation

• Avoid
• Pulling to hard
• Bending it too sharply (kinking)
• Forcing it through too tight an opening
• Each network node needs its own cable from the
  patch panel
• Cant splice
• Cant run too close to AC wires at least a foot
  apart
• Install highest quality and capacity cable
• Can run parallel coaxial or fiber

20
Composite cable

• Combines Cat5 and other transmission cables in a
  single PVC jacket
• Makes multiple-wire installation easier
• Saves cost of future wiring
• May contain
• Two Cat5 wires for network
• Two shielded RG-6 coaxial cables
• Fiber optic line

21
Plenum wiring

• An enclose in a building that moves air for
• Heating
• Cooling
• Humidity control
• Created by
• A false ceiling
• A false floor
• Metal duct work
• Contains high- or low-voltage wiring

continued
22
Plenum wiring, continued

• Cables must meet fire protection and
  environmental requirements
• To protect
• Enclose cables in a conduit
• Use cables with jackets
• Use cables made with fire resistant materials
• Use cables that are non-toxic at extreme
  temperatures
• Plenum cabling often coated with Teflon
• TP and coax both come in plenum cable types

23
Coaxial networks

• Supports older networks
• Contains a layer of braided wire or foil between
  the core and outside insulating layer
• Shielding protects from EMI
• Layer of plastic separates core from insulating
  layer to prevent data signal damage or loss
• Ethernet uses RG-58 (/U 53.5 ohms with solid
  copper)(AU indicates 50 ohms with a stranded
  copper core).
• Thinnet cable (1/4 diameter) -- Both AU and U
  are thinnet cables. Can carry data signals up to
  185 meters.

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Thinnet cable
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Thicknet cables

• RG-8 or RG-11 cables
• Dual shielding
• Dont bend easily
• Carry signals up to 500 meters
• Used for backbone, not node drops
• RG-59 (for cable TV) and RG-6 (for surveillance
  cameras) not suitable for networks
• RG-62 used for old ARCnet networks
• Check type carefully

26
A thicknet cable
27
Coax connectors

• Thinnet cables connect using a BNC barrel
  connector
• Segments use T-connectors
• Line end uses terminator
• Terminator prevents signal reflection

28
Coax cable connectors
29
NIC with coax connector
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Thicknet connectors

• Vampire tap
• Tap contains metal spikes
• Spikes penetrate cable to make connection
• Transceiver connects to cable via AUI port or DIX
  connector

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Thicknet vampire tap
32
Cat5 TP cable connectors

• RJ-45
• Eight wires
• RJ means Registered Jack
• is the wiring pattern
• EIA/TIA-568-A defines two wiring patterns
• T568A
• T568B
• Pins are numbered left to right, 1 8
• Pins connect to colored wires

33
RJ-45 and RJ-11 connectors
RJ-45
RJ-11
34
RJ-45 wiring
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EIA/TIA-568-A standards

• T568A preferred for residential
• T568B preferred for commercial
• Both electrically identical
• Pin 1 always to pin 1, pin 2 always to pin 2,
  etc
• Pick one standard and use it for all wiring

36
Terminating cable to an RJ-45 plug
37
Terminating CatX to RJ-45 jacks

• Use an RJ-45 punchdown tool
• Expensive versions use a compression spring
  hammering action
• Produces uniform connections
• Use type 110 IDC terminals
• Remove 1 ½ of jacket from cable
• Untwist full length of exposed wire pairs
• Place cable end onto jack
• Arrange wires into IDC slots
• Use punchdown tool
• Snap on protective cover

38
TIA 570 specifications

• Specifies residential telecommunications wiring
• Specifications include
• Topology
• Distribution devices
• Layouts for single and multiple family homes
• Performance criteria and field tests
• Auxiliary disconnect outlets
• Two grades 1 and 2

39
Fiber optic cables

• Carry light-based data through strands of glass
• Fastest and most expensive transmission media
• Used as backbone
• Used for long-distance lines
• Composed of
• Glass or plastic strand (core)
• Core clad in glass tube
• Outer, insulating, rubberized jacket

continued
40
Fiber optic cables, continued

• Single-mode or multi-mode
• Issues
• Most expensive to install and manufacture
• Data cant transmit through broken glass
• Benefits
• Not subject to EMI or wiretapping
• Very high transmission speed
• Little or no attenuation
• Length up to 10 miles
• Speeds 100 Mbps to 1 Gbps

41
Fiber optic cable connectors
42
Linking computers

• RS-232
• IEEE 1394/Firewire
• USB 2.0

43
RS-232

• EIA232
• Interface standard for data communications
  equipment
• Specifies
• Signal voltages
• Signal timing
• Signal function
• Protocol
• Mechanical connectors
• Employed in null-modem cables
• RS-232D uses RJ-45 connectors
• Max length is 50 feet 500 feet for asynchronous
  data

44
IEEE 1394/Firewire

• Create a peer-to-peer network between two Windows
  XP computers
• Max. cable length is 15 feet
• Communication speeds of 100, 200, and 400 Mbps
• Windows 2000 needs third-party product for
  Firewire networking
• Multiple Firewire ports can daisy chain for
  more than two computers
• Place repeaters every 15 feet for max of 237 feet.

45
Windows XP IEEE 1394/Firewire
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1394 Connection Properties
47
USB 2.0

• No designed to establish a LAN
• Use a USB bridge device between two computers
• Use a USB hug for more than two computers
• Cant direct connect two computers USB port to
  USB port with a USB cable
• USB 2.0 has data transfer rate of 480 Mbps

48
Network Interface Card

• Adapter card
• Plugs into expansion slot
• Connects externally through USB port
• NIC ports connect to network using cable
• Supports only one of the three
• Ethernet
• Token Ring
• FDDI
• Multiple type of ports for different cable types

continued
49
Network interface card, continued

• Function is to send and receive data
• Converts data into appropriate network signal
• Transceiver makes the conversion
• May have more than one type of transceiver

50
An Ethernet combo NIC
51
Examples of NIC cards
52
NICs

• Have MAC addresses
• Must match network architecture
• Most all are PCI cards
• Older cards
• Set IRQ, DMA, and I/O addresses

53
Wireless LAN

• Uses radio waves or infrared light
• Uses wireless NIC
• Wireless NIC uses antenna to send and receive
  signals
• Popular
• Where cable is difficult to install
• Where there are mobile users
• Communicate directly or through a WAP

54
Wired network with wireless segments
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Wireless network benefits

• Inventory is more convenient when employees can
  freely walk around the warehouse or organization
• Devices like personal digital assistants (PDAs)
  and Tablet PCs can be used in hospital wards to
  track patients, and doctor visits
• Mobile workers moving between offices, and
  telecommuters coming into the office, can more
  easily connect to the LAN from almost anywhere
• Online information is always available for
  research or information retrieval

continued
56
Wireless network benefits, continued

• Production on manufacturing shop floors can be
  readily evaluated
• Wireless network infrastructure can be moved to a
  new building more easily
• The cost of providing network access to buildings
  is substantially lowered

57
WAN issues

• Slower than wired networks
• Security

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Wireless protocols

• Wi-Fi (Wireless Fidelity)
• Bluetooth
• 802.11a
• WiMax
• IEEE1394
• IEEE 802.11g
• USB

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Ethernet

• Most popular LAN
• Good balance between
• Ease of setup
• Use
• Speed
• Cost
• Three types
• 10-Mbps Ethernet
• 100-Mbps Ethernet
• 1000-Mbps Ethernet (Gigabit Ethernet)

continued
60
Ethernet, continued

• Most use STP, UTP or fiber-optic cable
• Older installations use thin Ethernet or thick
  Ethernet

61
Ethernet topologies

• Bus topology
• Star topology

62
Bus and star Ethernet designs
63
Comparing star and bus designs

• Star may be slower than bus, especially with many
  nodes
• Star may have more data collisions

64
Combined bus and star designs
65
Token Ring

• Operates at slower speeds than Ethernet
• Physically arranged in a star
• Protocol for data control uses a token
• All data travels in a circle (ring) on the
  network
• Each node is connected to a MAU by two wires
• Token travels up and down wires and between MAUs

66
A Token Ring network
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Wireless networks

• Communicate with an access point or wireless hug
• NIC includes transceiver and antenna
• Communicates over short distances using radio
  waves

68
A wireless network design
69
Fiber optic cable networks

• FDDI
• Large, fast networks
• Almost exclusively use fiber optic cables
• Communication speeds of 100 Mbps
• Used in large commercial buildings and backbones
  to join LANs

70
WAN bandwidth technologies

• T lines and E lines
• X.25 and frame relay
• ATM
• Mesh topology

71
Unit summary

• Identified the components of a network
• Described wired network connections
• Compared wireless networking standards
• Described the different network architectures