Computers Are Your Future

1
Computers Are Your Future

• Chapter 8
• Networks Communicating and
• Sharing Resources

2
Network Fundamentals

• A computer network
• LAN
• WAN

3
Communication Devices
computers

• Computers, modems, routers, switches, hubs,
  wireless access points, and network interface
  cards are all communication devices.

modems
routers
switches or hubs
Network Interface Cards
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Communication Devices

• Computer connected to a network node or host
• Contains a network interface card (NIC)?

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Communication Devices

• Routers connect two or more LANs or WANs
• Can determine the best path to route data.
• LANs often use a hub or a switch to create the
  network.

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Network Fundamentals

• Network administrators
• Install
• Maintain
• Support
• Interact with users
• Troubleshoot problems

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Advantages of Networks

• Connecting people
• Reduced hardware costs
• Application sharing
• Sharing information resources
• Centralized data management

8
Disadvantages of Networks

• Loss of autonomy
• Lack of privacy
• Security threats
• Loss of productivity

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Local Area Networks (LANs)?

• Computer network that spans small geographical
  area and has higher transfer rate
• Network administrator

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LAN Hardware and Software

• Networking Hardware
• Network interface card (NIC)?

• Networking Software
• Operating system that supports networking
  protocols (Unix, Linux, Windows, Mac OS)?
• Additional system software

NIC
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Wide Area Networks (WANs)?

• WANs cover a wide geographic area. They are
  used to connect LANs.
• use leased lines
• contain long-distance trunk lines called
  backbones.
• Examples The Internet, the ATM network

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Backbones

• Backbones, high-capacity transmission lines
• Internet backbones can carry 2.5 Gbps

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Client-Server Networks

• Typical corporate networks are client-server.

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Peer-to-Peer (P2P) Networks

• Nodes in the network are equal peers.
• Examples home networks, file sharing programs
  napster, kazaa. See File Sharing in Wikipedia.

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LAN Topologies

• LAN Topology
• The problem of contention
• Collisions or corrupt data

Bus topology
Star topology
Ring topology

• All workstations are attached in a circular
  arrangement
• A special unit of data called a token travels
  around the ring
• Workstations can only transmit data when they
  possess a token
• Token Ring

• Called a daisy chain
• Every workstation is connected to a single cable
• Difficult to add workstations

• Contains a hub or central wiring concentrator
• Easy to add workstations
• Ethernet

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Protocols

• Network Protocol
• Protocol suite

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Protocol Stack
receiving
sending
user
user
Protocol layer
stack
physical media
physical media

• A protocol stack is a a way to arrange software
  that implements communication protocols in order
  to manage their complexity.

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Wi-Fi

• Wireless-fidelity
• Wireless LAN
• Uses a central server (router) or access point
• 10 Mbps

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WAN Protocols

• X.25 is the oldest packet switching protocol it
  is used by ATMs and credit card authorization
  devices.
• TCP/IP (Transmission Control Protocol/Internet
  Protocol)?
• Asynchronous Transfer Mode (ATM) Used by the
  telephone networks. Designed to offer real-time
  transmission of video and audio data.

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Switching and Routing Techniques

• Packet switching
• Outgoing messages are divided into fixed-size
  data units called packets.
• Packets are numbered and addressed to the
  receiving computer.
• Routers examine the packets and send them to
  their destination.

• Circuit switching
• Networks create an end-to-end circuit between the
  sending and receiving computers.
• Transmission delays are constant during
  transmission
• Data packets are received in order they were sent.

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Advantages and Disadvantages of Circuit and
Packet Switching