WXES2106 Network Technology Semester 1 20042005

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WXES2106Network TechnologySemester 1 2004/2005

• Chapter 2
• Networking Media

CCNA1 Module 3, 4 and 5
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Contents

• Introduction
• Copper Media
• Optical Media
• Wireless Media
• Cable Testing
• Cabling the LAN
• Cabling the WAN

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Introduction

• Proper selection of cabling is key to efficient
  network operation.
• Copper cable is used in almost every LAN
• Optical fiber is the most frequently used medium
  for the longer, high bandwidth, point-to-point
  transmissions required on LAN backbones and on
  WANs.
• Different specifications for cable
• Speed of bit transmission (bps)
• Transmission type (Base or Broad)
• Maximum distance
• Example 10BASE-T, 10BASE5, 10BASE2

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Introduction
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Copper Media

• Coaxial Cable
• Longer distance
• Thicknet coaxial cable more expensive to install

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Copper Media
Screened UTP (ScTP)

• Shielded twisted-pair cable (STP)

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Copper Media

• UnShielded twisted-pair cable (STP)
• Easy to install and less expensive
• Type of connection Straight through, Crossover,
  Rollover

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Copper Media
Straight through
Crossover
Rollover
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Optical Media
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Optical Media

• Every fiber-optic cable used for networking
  consists of two glass fibers encased in separate
  sheaths.
• One fiber carries transmitted data from device A
  to device B. The second fiber carries data from
  device B to device A.
• This provides a full-duplex communication link.

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Optical Media
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Optical Media

• Connectors are attached to the fiber ends so that
  the fibers can be connected to the ports on the
  transmitter and receiver.
• Subscriber Connector (SC connector) - Multimode
  fiber
• Straight Tip (ST) connector - Single-mode fiber

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Optical Media

• Optical Receiver
• Use PIN photodiodes to detect laser/LED light
• PIN photodiodes absorb light of 850, 1310, or
  1550 nm
• When detects light, produces electrical signal
  for network
• Installation of Fiber
• Pull fiber through interducting (stiffer piping)
  to reduce bends
• Cleave (cut) polish ends
• Attach connector

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Optical Media
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Wireless Media
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Wireless Media

• A wireless network may consist of as few as two
  devices
• Access Point
• Central hub for WLAN
• It is hard wired to the cabled LAN to provide
  Internet access and connectivity to the wired
  network.
• Equipped with antennae and provide wireless
  connectivity over a specified area referred to as
  a cell.
• The range will be from 91.44 to 152.4 meters
• Wireless NIC

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Wireless Media

• Wireless Connectivity
• When a client is activated within the WLAN, it
  will start "listening" for a compatible device
  with which to "associate".
• A probe request is sent from the wireless node
  seeking to join the network.
• The probe request will contain the Service Set
  Identifier (SSID) of the network it wishes to
  join.
• When an AP with the same SSID is found, the AP
  will issue a probe response.
• The authentication and association steps are
  completed.

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Wireless Media

• Authentication and Association types
• Unauthenticated and unassociated
• The node is disconnected from the network and not
  associated to an access point.
• Authenticated and unassociated
• The node has been authenticated on the network
  but has not yet associated with the access point.
  
• Authenticated and associated
• The node is connected to the network and able to
  transmit and receive data through the access
  point.

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Wireless Media

• Authentication Process
• Open System
• The SSID must match.
• Shared Key
• Requires the use of Wireless Equivalency Protocol
  (WEP) encryption.
• Nodes attempting to access the network through
  the AP must have a matching key.

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Wireless Media
Adaptive Rate Selection
Frame Type
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Wireless Media

• Wireless Security
• EAP-MD5
• Extensible Authentication Protocol
• LEAP (Cisco)
• Lightweight Extensible Authentication Protocol
• Provides security during credential exchange,
  encrypts using dynamic WEP keys, and supports
  mutual authentication.
• User authentication
• Encryption
• Data authentication

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Cable Testing

• Inferior quality of network cabling results in
  network failures and unreliable performance.
• All media require testing to determine the
  quality.
• Attenuation (signal deterioration) and noise
  (signal interference) cause problems in networks
  because the data is not recognizable when it is
  received.
• Proper attachment of cable connectors and proper
  cable installation are important.

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Cable Testing

• Cable Testing Standard
• Wire map
• Insertion loss
• Near-end crosstalk (NEXT)
• Power sum near-end crosstalk (PSNEXT)
• Equal-level far-end crosstalk (ELFEXT)
• Power sum equal-level far-end crosstalk
  (PSELFEXT)
• Return loss
• Propagation delay
• Cable length
• Delay skew

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Cable Testing
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Cabling the LAN
Media Types Symbol
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Cabling the LAN
LAN Physical Layer Implementation
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Cabling the LAN

• Ethernet is the most widely used LAN technology.
• An Ethernet speed of 10 Mbps can be used at the
  user level to provide good performance.
• Fast Ethernet can be used to connect enterprise
  servers.

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Cabling the LAN
Ethernet Media
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Cabling the LAN
Ethernet Media
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Cabling the LAN

• Straight-through
• Switch to router
• Switch to PC or server
• Hub to PC or server
• Crossover
• Switch to switch
• Switch to hub
• Hub to hub
• Router to router
• PC to PC
• Router to PC
• Rollover
• A terminal and a console port

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Cabling the LAN

• Wireless networks use radio Frequency (RF),
  laser, infrared (IR), or satellite/microwaves to
  carry signals from one computer to another
  without a permanent cable connection.
• A wireless network can be created with much less
  cabling than other networks.

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Cabling the LAN

• In LAN design, no more than four repeaters can be
  used between hosts on a LAN. This rule is used to
  limit latency added to frame travel by each.
• Using a hub changes the network topology from a
  linear bus, where each device plugs directly into
  the wire, to a star.
• Bridge break up a large LAN into smaller, more
  easily managed segments.
• Switch alleviates congestion in Ethernet LANs by
  reducing the traffic and increasing the
  bandwidth. It operates at much higher speeds than
  bridges and can support new functionality, such
  as virtual LANs.

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Cabling the LAN
Micro Segmentation of Network
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Cabling the LAN

• Peer-To-Peer
• Networked computers act as equal partners, or
  peers. As peers, each computer can take on the
  client function or the server function.
• Client/Server
• Network services are located on a dedicated
  computer called a server. The server responds to
  the requests of clients. The server is a central
  computer that is continuously available to
  respond to requests from clients

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Cabling the LAN
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Cabling the LAN
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Cabling the WAN
WAN Physical Layer
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Cabling the WAN
WAN Serial Connection
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Cabling the WAN

• Routers are responsible for routing data packets
  from source to destination within the LAN, and
  for providing connectivity to the WAN.

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