Chapter 5 Networks Communicating and Sharing Resources
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Chapter objectives: Understand basic networking. Discuss the
advantages and disadvantages of networks. Distinguish between
Peer-to-Peer & client/server LAN. Define topology and
understand how 3 LAN topologies differ. Explain the importance of
protocols. Most widely used protocol & its versions. Identify
the special components of wide area network (WAN) that
differentiate from LAN.
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Network Definition 9A-3 Set of technologies that connects
computers to allow communication and collaboration between users. A
group of two or more computer systems linked together to exchange
data. Any device connect to the network referred to as a node. Any
device has a unique logical address (name). Any device also has a
unique physical address (MAC). A node need NIC to connect to
network.
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The Uses of a Network 9A-4 Simultaneous access to data Data
files are shared Shared files stored on a server Software can be
shared Shared peripheral device Printers and faxes are common
shares Reduces the cost per user Devices can be connected to the
network
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The Uses of a Network 9A-5 Personal communication Email
Conferencing Voice over IP Phone communication over network wires
Easier data backup Backup copies data to removable media Server
data backed up in one step
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Sharing Data 9A-6 File server contains documents used by other
computers.
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Advantages and Disadvantages of Networking: Advantages: Reduce
hardware costs. Sharing application. Sharing information resources.
Centralized data management. Connecting people. Disadvantages: Loss
of autonomy. Lack of privacy. Security Threats. Loss of
productivity.
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Common Network Types 9A-8 Local Area Network (LAN) LAN
interconnects devices in a limited area such as a home, school, or
office building using network media. Contains printers, servers and
computers. Systems are close to each other. Organizations often
have several LANS. LANs Types Wired LAN Wireless LAN VLAN LAN
Protocol: Standard or Rules specify how two dissimilar network
components can establish a communication.
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Wired LAN Network Cables Unshielded Twisted Pair (UTP) Cable
Shielded Twisted Pair (STP) Cable Coaxial Cable Fiber Optic Cable
Ethernet: the most popular cabling technology in LAN. Ethernet uses
a protocol called CSMA/CD Twisted Pair cableCoaxial cable Fiber
Optic cableRj-45 connector
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Network Interface Card 9A-10 Connects node to the media Unique
Machine Access Code (MAC)
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StandardMax SpeedTypical Range 802.11a54 Mbps150 feet 802.11b11
Mbps300 feet 802.11g54 Mbps300 feet 802.11n100 Mbps300+ feet
Wireless LANs Wifi standards and speeds Wi-Fi: wireless LAN
standard that offers Ethernet speeds through the use of radio waves
instead of wires.
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Network layers
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Types Of (LAN)Structure
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Peer-to-Peer Network(P2P): 1. Tend to slow down as the number
of users increase. 2. Keeping track of all the shared folders &
files can be confusing. 3. Security not strong because the lack of
hierarchy. 4. Nodes access resources on other nodes 5. Each node
controls its own resources
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Client/Server network 9A-15 Nodes and servers share data roles
Nodes are called clients Servers are used to control access
Database software Access to data controlled by server Server is the
most important computer Virtual Private Network (VPN) Operates a
private network over the internet
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LAN Topologies Network Topology: the physical layout of the
LAN. 1) Bus Topology. 2) Star Topology. 3) Ring Topology.
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1- Bus Topology
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One wire or cable connects all nodes. Terminator special
connectors ends the circuit. Advantages Simple, reliable and easy
to expand Easy to setup Small amount of wire Disadvantages: Only
one node can transmit at a time. Slow & Easy to crash Used at
home or small office.
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2- Star Topology
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Solves the expansion problems of the bus topology. All nodes
connect to a hub Packets sent to hub Hub sends packet to
destination Advantages Easy to setup and add users. One cable can
not crash network Disadvantages Loss of hub crash down the entire
network Uses lots of cable Most common topology used at office
buildings, computer labs and WAN.
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3- Ring Topology
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Nodes connected in a circle. Not in common used today. Special
unit of data called Token travels around the ring and is used to
transmit data Nodes can transmit only when it posses the token.
Advantages Time to send data is known No data collisions
Disadvantages Slow Lots of cable Well suited for use within a
division of a company or on one floor of a multi floor
building.
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9A-23 Two or more LANs connected Over a large geographic area
Typically use public or leased lines Phone lines Satellite The
Internet is a WAN Wide Area Networks (WAN)
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WAN PROTOCOLS TCP/IP are open protocols that define how the
Internet works. IP defines the internet addressing scheme. TCP
defines how one computer can contact another to exchange control
and confirmation messages. Circuit switching A protocol (method)
used in a telephone systems with direct connection between the
communicating devices. Packet switching A method used when no
effort is made to create a single direct connection between the
communicating devices.
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Network Hardware 9A-25 SwitchesHubs Replacement for hubs Only
intended node receives transmission Fast and secure Center of a
star network All nodes receive transmitted packets Slow and
insecure
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Network Hardware 9A-26 GatewayRouterBridge Connects two
dissimilar networks Connects coax to twisted pair Most gateways
contained in other devices Connects two or more LANs Packets sent
to remote LAN cross Network is segmented by IP address Connect
internal networks to the Internet Need configured before
installation Connects two or more LANs together Packets sent to
remote LAN cross,other packets do not cross Segments the network on
MAC addresses
