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Communications and Networks

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Uses of communications technologies. Internet. Global Positioning System (GPS) ... Cell phones, mobile devices. High frequency radio waves. 824 to 849 MHz. Microwaves ... – PowerPoint PPT presentation

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Title: Communications and Networks


1
Communications and Networks
Reading Chapter 9
2
Why are networks so useful?
  1. They facilitate communications
  2. They allow for sharing of resources
  3. Both of the above

3
Network
  • Uses of communications technologies
  • Internet
  • Global Positioning System (GPS)
  • Short Message Service (SMS)
  • Network
  • Interconnected group of computers and devices
    connected via communications devices and media
  • Facilitates sharing of resources and supports
    communications
  • Requires
  • Sending receiving devices
  • Communications devices
  • Communications channel or path
  • Network OS (NOS)

4
Networks Communications Devices
  • Communications Device
  • Hardware capable of sending/receiving data
  • Convert signals so that they are suitable for the
    communications channel
  • May convert between analog and digital
  • Common types
  • Dial-up modems
  • ISDN and DSL modems
  • Cable modems
  • Network interface cards
  • Wireless access points
  • Routers

5
Networks Communications Devices
  • Dial-up Modem
  • Modulate/demodulate
  • External modem
  • Connects to serial or RS-232 port
  • Internal modem
  • Card inserted to expansion slot/PC Slot
  • ISDN and DSL Modems
  • Do not modulate/demodulate
  • External
  • Sends and receives data over a digital telephone
    line
  • ISDN line
  • DSL line

6
Networks Communications Devices
  • Cable modem
  • Cable television network
  • Faster than dial-up access or ISDN line
  • Splitter runs separate cables to TVs and cable
    modem
  • External
  • USB port or Ethernet NIC via a cable
  • Network Interface Card (NIC)
  • Coordinates transmission/receipt of data to/from
    the device
  • Card installed in an expansion slot of a PC,
    printer, PC slot
  • Wireless transmission includes antenna
  • Works with a particular network technology
  • Ethernet or token ring

7
Networks Communications Devices
  • Hub
  • Provides a central point of connectivity for
    cables in a network
  • May include a router
  • Router
  • Connects multiple computers and routers together
  • Transmits packets to correct destination
  • May include built-in firewall
  • Wireless access point
  • Allows computers and devices to communicate
    wirelessly
  • Allows data transfer to a wired network

8
Communications devices include ______.
  1. routers
  2. hubs
  3. modems
  4. NICs
  5. All of the above

9
Networks Communications Channels
  • Channel
  • Communications path between two devices
  • Transmission rate
  • Speed at which data flows through the channel
  • Bandwidth of the channel
  • Bits per second (bps), Hertz (cycles per second)
  • Transmission media
  • Materials or techniques capable of carrying one
    or more signals
  • Baseband media carry one signal at a time
  • Broadband media carry multiple signals
    concurrently
  • Physical transmission media
  • Twisted pair, Coaxial, Fiber Optic
  • Wireless transmission media
  • Infrared, Radio Frequency, Infrared, Microwave

10
Networks Physical Transmission Media
  • Twisted-pair cable
  • Used for network cabling and telephone systems
  • One or more twisted-pair wires bundled together
  • Each pair has two insulated copper wires twisted
    together
  • Coaxial cable (coax)
  • Used for network cabling and cable TV
  • Single copper wire surrounded by 3 layers
  • Insulating material
  • Woven/braided metal
  • Plastic outer coating

11
Networks Physical Transmission Media
  • Fiber optic cable
  • Light used to send signals
  • Thin glass or plastic strands
  • Surrounded by insulating glass cladding and a
    protective coating
  • Carries many signals
  • High speed
  • Less noise
  • Smaller size
  • Expensive, difficult to install and modify

Protective coating
12
Networks Physical Transmission Media
13
All of the following except ______ are examples
of physical media.
  1. coaxial cable
  2. twisted pair
  3. microwave cable
  4. fiber optic cable

14
Networks Wireless Transmission Media
  • Microwaves
  • High-speed signal transmission
  • Signals sent between microwave stations
  • Fixed-point wireless
  • Requires line-of-sight
  • Communications Satellites
  • Satellite receives microwave signal and amplifies
  • Retransmits over wide-area, to a number of
    land-based stations
  • Radio Frequency
  • Antenna, transmitter, receiver
  • Bluetooth (2.45 GHz)
  • 802.11b g (2.4 GHz)
  • Cellular Radio Waves
  • Cell phones, mobile devices
  • High frequency radio waves
  • 824 to 849 MHz
  • Infrared Signals
  • IR light waves with line-of-sight transmission

15
Networks Wireless Transmission Media
16
All of the following except ______ are examples
of wireless media.
  1. microwaves
  2. satellites
  3. radio frequency waves
  4. fiber optic waves

17
Networks
  • Classified according to
  • Geography Geographic Distribution
  • LAN
  • MAN
  • WAN
  • Architecture
  • Topology
  • Protocol/Communications Technology

18
Networks Geographic Distribution
  • Local Area Network (LAN)
  • Connects computers in a limited geographical area
  • Each computer and device is a node
  • Metropolitan Area Network (MAN)
  • High-speed network that connects LANs in a
    metropolitan area
  • Managed by a consortium of users or a single
    network provider

19
Networks Geographic Distribution
  • Wide Area Network (WAN)
  • Connects computers and devices in a large
    geographical area
  • Connected via many types of media
  • One large network or two or more interconnected
    LANs, MANs
  • Others
  • CAN
  • HAN
  • TAN

20
A ______ is a network that encompasses a limited
geographic area.
  1. MAN
  2. WAN
  3. LAN
  4. PAN

21
Networks
  • Classified according to
  • Geography
  • Architecture Broad outline of the network
  • Peer-to-Peer
  • Client/Server
  • Topology
  • Protocol/Communications Technology

22
Network Architectures Client/Server and
Peer-to-Peer
  • Client/Server
  • Server controls resources
  • More storage space, power
  • Serves as a repository
  • Dedicated servers
  • Client relies on the server for access to
    resources
  • Peer-to-Peer
  • Share peripheral devices
  • Up to 10 peer computers
  • NOS applications software, storage
  • Internet Peer-to-Peer (P2P)
  • Users connect directly to each others hard disk
  • Popular, inexpensive

23
Networks
  • Can be classified according to
  • Geography
  • Architecture
  • Topology Physical arrangement of devices
    connected to the network
  • Bus
  • Ring
  • Star
  • Networks often use a combination of topologies
  • Protocol/Communications Technology

24
Network Topologies Bus and Ring Networks
  • Bus Network
  • Single central cable connects computers and
    devices
  • Transmits in both directions
  • If a device fails, network continues to function
  • Reliable
  • Popular, inexpensive
  • Ring Network
  • Cable forms a closed ring
  • Transmits in only one direction
  • If one device fails, all those after the device
    cannot function
  • Spans larger distance than bus network
  • LANs and WANs

25
Network Topologies Star and Other Networks
  • Star Network
  • Devices connect to a central computer
  • Hub
  • If one device fails, only that device is affected
  • Hub fails
  • Other Topologies
  • Mesh
  • Redundant interconnections between nodes
  • Tree
  • Star networks connected together via a bus

26
With ______ topology, the devices on the network
are connected together in a closed loop.
  1. bus
  2. ring
  3. star
  4. tree

27
Networks
  • Can be classified according to
  • Geography
  • Architecture
  • Topology
  • Protocol/Communications Technology Standards
    that govern how data/instructions flow over the
    network
  • Ethernet
  • Token Ring
  • TCP/IP
  • WAP
  • Others

28
Networks Network Communications Technologies
  • Communications Protocol
  • Set of rules and procedures for exchanging
    information among computers
  • Ethernet
  • Token ring
  • TCP/IP
  • WAP
  • Others

29
Network Communications Technologies Ethernet
  • Ethernet
  • Widely used LAN standard
  • Developed by Xerox, DEC, Intel - 1976
  • Fast Ethernet (100Base-T) - 100 Mbps
  • Gigabit Ethernet - 1000 Mbps
  • 10-Gigabit Ethernet 10 Gbps
  • Bus or star topology
  • PCs in the network to contend for access
  • Collision

30
Network Communications Technologies Token Ring
  • Token Ring
  • Ring or star topology
  • LAN standard
  • Passes a signal called a token
  • Special bit pattern
  • Only device with token can transmit
  • Device catches the token, attaches message ,
    sends it to travel around the network to
    receiving device
  • Receiving device catches token, strips off the
    message, resends token

31
Network Communications Technologies TCP/IP
  • TCP/IP
  • Used to connect hosts on the Internet
  • Includes several protocols
  • Transmission Control Protocol and Internet
    Protocol
  • Data broken up into small packets
  • Origin information
  • Destination information
  • Sequence information
  • Data/information/instructions
  • Packet switching
  • Break up message into packets, route packets,
    destination reassembles the message
  • Routers direct packets individually along fastest
    path

32
Network Communications Technologies WAP
  • Wireless Application Protocol (WAP)
  • Access Internet via mobile devices
  • 2.0 Specification
  • Open Mobile Alliance (OMA)
  • Web sites provide wireless content to display on
    microbrowsers
  • WML XML application designed for small screens

33
Network Communications Technologies 802.11,
Bluetooth, IrDA
  • IEEE 802.11 (802.11b, g WiFi)
  • Family of standards used with wireless LANs
  • Used for public Internet access points
  • Bluetooth
  • Devices contain special chip
  • Short-range radio waves transmit between
    Bluetooth devices
  • Short distance
  • IrDA
  • IrDA devices contain IrDA ports
  • Infrared light waves
  • Line-of-sight transmission

34
With TCP/IP is used to send data over the
Internet, the data is divided into small pieces
or ______.
  1. bundles
  2. packets
  3. tokens
  4. hubs

35
Networks Intranets
  • Intranet
  • Internal network in an organization used to share
    information
  • Uses Internet technologies (TCP/IP, Web server,
    Web pages)
  • Enterprise network
  • Connects to the Internet
  • Extranet - Allows outside user access
  • Firewall
  • Designed to prevent unauthorized access to a
    private network
  • Firewall blocks messages that do not meet
    security criteria
  • Uses hardware, software, combination of both
  • All messages entering or leaving the intranet
    must pass through the firewall

36
Networks Home Area Networks (HAN)
  • Network within a home
  • Connects digital devices
  • HomePLC electrical lines cables connect
    card/USB/parallel port to wall outlet
  • Phoneline telephone lines cables connect
    NIC/PC card to telephone jack

Network card that plugs into PCI slot and wall
outlet for home power-line network Howstuffworks.
com
  • HomeRF, 802.11b radio waves NIC connects to
    transceiver with antenna or to wireless access
    point
  • Ethernet twisted pair cables Ethernet NIC
    cards and cables to connect devices

37
Do you have a home area network?
  1. Yes
  2. No

38
Networks Summary
  • Uses of Communications Technology
  • Networks
  • Communications Devices
  • Communications Channels
  • Physical and Wireless Transmission Media
  • Geographic
  • LAN, MAN, WAN
  • Architectures
  • Peer-to-Peer, Client/Server
  • Topologies
  • Bus, Ring, Star
  • Protocols
  • Ethernet, Token Ring, TCP/IP, WAP, 802.11, others
  • Intranets and Firewalls
  • Home Networks
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