Agenda

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Agenda

• Lecture Communications and Networks
• Test Review

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Why is networking computers advantageous?

• Sharing networked hardware and software can
  reduce costs
• Sharing networked hardware can provide access to
  a wide range of services and specialized
  peripheral devices
• Sharing data on a network is easy
• Networks enable people to work together
  regardless of time and place

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Why is geographic scope important?

• Local Area Network
• Metropolitan Area Network
• Wide Area Network

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Types of networks

• Intranet
• Network that is internal to a particular company
• Extranet
• Intranet that allows limited access to users
  outside

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What is the difference between a client/server
network and a peer-to-peer network?

• Client/server contains servers and clients
• Peer-to-peer (P2P) every computer is considered
  an equal

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What kinds of network devices are part of an ISP?
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Topology

• The configuration of the network
• Star, Bus and Ring are common
• The physical topology refers to the layout of the
  cables
• The logical topology refers to the path that the
  data takes

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How are devices on a network physically arranged?
Star Topology
Tree Topology
Ring Topology
Bus Topology
Mesh Topology
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Star topology

• Each individual node (computer or phone) is
  directly connected to a central host
• Todays phone system is an example
• Your home phone is directly connected to one of
  the several main phone switches in Colorado
  Springs

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Bus topology

• Each node is connected to the same piece of coax
• Cable TV is a good example
• Cable company runs a single cable down your
  street, and each house on your street connects
  into that cable

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Star/ring

• Looks like a star, but acts like a ring
• Most Ethernet networks are star/rings
• Uses a hub or switch to create the ring

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Network components

• Clients (workstations or PCs)
• Transmitting device
• Modem or NIC card
• Channel
• Coax, fiber, wireless
• Local Area Network device
• Switch or hub

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Other network components

• Router
• Used to route messages outside the LAN
• Host computer
• Mainframe that can be part of a LAN or WAN (wide
  area network)
• Server
• Special purpose PC that holds information for us

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LAN with router
To the internet
router
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Media

• Twisted pair
• Traditional phone wires
• Slowest, most available, least secure
• Very susceptible to noise
• Coax
• Phasing out, still a lot around
• More secure, better insulated against noise

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Media

• Fiber
• Fastest media, most expensive, impervious to
  noise, most secure
• Microwave
• Wireless, good for miles as long as you can see
  both ends, not secure
• Very flexible

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Media

• Satellite
• Very high speed, costly, requires supporting
  equipment (the satellites)
• 802.11 a/b/g
• Wi-Fi, inexpensive, provides wireless LAN
  connectivity

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Whats a packet?

• When you transmit data, it is broken up into
  small pieces called packets
• A packet is a parcel of data that is sent across
  a network
• Has the address of its sender
• Has the address of the destination
• Has some data
• When they reach the destination, they are put
  back together into original form

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How does Ethernet work?
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Ethernet is the most widely used network

• Also called CSMA/CD
• Also called 802.3

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What equipment is required for Ethernet
installations?

• An Ethernet card is a type of network interface
  card designed to support Ethernet protocols
• A hub is used to connect more than two computers
• Each network device requires one of the hub ports
• You can add hubs using an uplink port

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What equipment is required for Ethernet
installations?
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What is Token Ring technology?

• A Token Ring network, defined by the IEEE 802.5
  standard, passes data around a ring topology
  using a signal called a token to control the
  flow of data

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What is the FDDI standard?

• FDDI (Fiber Distributed Data Interconnect) offers
  100 Mbps speeds over fiber-optic cables
• Popular campus network technology

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What is Wi-Fi?

• Wireless LANs are slower but eliminate unsightly
  wires
• Signals can be disrupted by large metal objects,
  cell phones, pagers, and other wireless devices
• Most popular is 802.11 sometimes called WiFi for
  wireless fidelity
• Range of up to 150 feet
• Bluetooth
• 1 Mbps, range of 30 feet

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Wireless LAN technologies

• Eliminates the need for cabling
• 802.11 a
• 54 Mbps speeds
• 802.11 b
• 11 Mbps speeds
• 802.11 g
• 54 Mbps speeds
• 802.11 g
• 54 Mbps speeds

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HomePNA and HomePNC Networks

• HomePNA uses a special NIC and cable to connect
  each computer to a standard telephone wall jack
• Network frequency is usually different from
  voice, so can use network at same time you place
  a call
• You cannot make a call when dial-up Internet
  connection is active however
• HomePLC uses special NIC to connect to standard
  electrical outlet, but power fluctuations can
  adversely affect signal

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How do I specify which resources can be shared by
other workstations?

• Each workstation can specify whether its files or
  printer will be accessible to other workstations
  on the network
• Drive mapping is Windows terminology for
  assigning a drive letter to a storage device
  thats located on a different workstation

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LANs

• Used to share resources
• Like printers or software
• Site license required when sharing software
  instead of individual licenses
• Drive mapping
• Assigning a drive letter to a storage device on
  another machine
• Just like your NT accounts on S drive

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LANs

• Although local in geographical area, can be
  connected to a wide area network
• A router is the device that connects to a LAN and
  a wide area network to provide all LAN users
  access
• This creates a security problem

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LAN security

• Use a firewall if you have outside access
• Use network address translation (NAT) is you have
  outside access
• The routers IP address is visible to all
• Assigning different IP addresses to the LAN
  machines protects their IP addresses

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How does data flow across the Internet?

• Circuit switching method
• First step, find a route and lock it up
• Now transmit everything at once
• Packet switching method
• Divide your data into packets
• Now just send them over the Internet
• The destination address on each packet will allow
  the routers to deliver them

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Internet Protocols

• TCP/IP provides a standard that is fairly easy to
  implement, public, free, and extensible
• The Internet is not owned, operated, or
  controlled by any single entity
• TCP/IP is glue that holds the Internet together

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Is TCP/IP the only Internet Protocol?
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IP Addresses Does the Internet use a special
addressing scheme?

• The IP part of TCP/IP defines the format for the
  addresses that identify computers on the Internet
• These addresses are called IP addresses
• An IP address is a series of numbers, such as
  204.127.129.001
• It is separated into four sections by periods
• Each sections number cannot exceed 255
• Each address requires 32 bits (8 bits per section)

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Domain Names Whats a domain name?

• People find it difficult to remember long strings
  of numbers, so host computers also have names
  called domain names
• Domain name fully qualified domain name
  (FQDN), usually typed in all lowercase
• Key component of URLs and e-mail addresses
• www. msu.edu/biologycatalog.htm - www.msu.edu is
  the domain name

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A Communication System consists of

• Creator and User of data (can be computers)
• Communication devices
• Modems
• Communication channels
• Phone lines, satellite, microwave
• Network software and Protocols

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Communication System Components
User
Creator
Media
Communication Device
Communication Device
Protocols
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A Communication System

• Just a bunch of COMPATIBLE hardware and software
  components
• Computers, faxes, phones
• Cabling, coax, microwave
• Modems
• Operating systems, application systems, database
  systems

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Protocols

• Rules for determining how the devices will
  communicate
• TCP/IP is one protocol
• used extensively throughout the internet
• OSI is another protocol
• used in many business networks

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Signals travel in two forms

• Analog
• Digital

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Analog Signals

• Continuous signal
• Usually used for voice communications
• phone calls
• Slower speeds

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Digital Signals

• Waveforms are squared to represent ones and zeros
• Exists in one of two states
• Used for voice and data communication

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How does a modem work?

• Modem derived from modulate and demodulate
• Modulation changing characteristics of a signal
  (digital to analog)
• Demodulation changing signal back to original
  state (analog to digital)

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How does a dial-up connection work?

• While connected to your ISP, your call is routed
  through the telephone companys local switch to
  the ISP

Local Switch
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DSL, Cable, ISDN, T1, and T3

• Several services such as DSL, Cable, ISDN, T1,
  and T3 take advantage of full capacity of the
  telephone connections (normal dial-up services do
  not)
• Offers high-speed digital communications links
  for voice and data

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Communication Channels have a certain

• Transmission speed
• Bandwidth
• The bandwidth of a channel is measured in bits
  per second (bps)

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Transmission Media Analogy

• Think of the transmission line (phone line, coax
  cable, etc.) as a pipe
• You are transmitting data down that pipe

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Transmission Media Analogy

• Bandwidth is how wide the communication pipe is
• Data rate is how fast bits are flowing through
  the pipe

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Types of communication

• Simplex
• One direction only
• Radio signals
• Half-duplex
• Both directions, but only one at a time
• CB, or walkie-talkies
• Full duplex
• Both directions simultaneously
• Telephone

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Two types of phone lines

• Switched
• Your normal telephone system
• Dedicated
• Used by businesses and governments

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Test Results

• C- 60
• D 56.7
• D 50
• D- 46.7

• A 90
• A- 86.7
• B 83.3
• B 76.7
• B- 73.3
• C 70
• C 63.3

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Test Results

• HI 99
• AVG 77
• LOW 47

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Break