Transcript Networks - Department of Computer and Information Science

Networks
CSCI-N 100
Dept. of Computer and
Information Science
The Basics
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Early years networks were scarce
Early PCs worked as standalone
Interaction limited to one person with software
Engineers anticipated networking has
advantages
Bob Metcalf, 1975, Ethernet
Network Classification
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PAN – personal area
network
NAN – neighborhood
area network
LAN – local area
network
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MAN – metropolitan area
network
WAN – wide area
network
PAN – personal area network
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Personal devices
Usually within 30 feet
No cables or wires
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Example – wireless
transmission of data
from computer to PDA,
cell phone, printer
NAN – neighborhood are network
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Limited within a
geographic area
Spread over several
buildings
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Example - local
Starbucks
LAN – local area network
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Limited to a very small
geographic area
Usually one building
Can be wired or wireless
Type of network most
likely to work with in
school, business, home
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Example – school
computer labs, home
networks
MAN – metropolitan area network
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Public
High speed access
Voice and data
transmission
Range about 50 miles
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Example – ISP, cable
television, local
telephone
LAN Standards
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Standard by the Institute of Electrical and
Electronic Engineers (IEEE)
Designation number refers to standard
Helps to identify compatible network
technologies
Ethernet, WiFi for home, business
Connections
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Node
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point on a network
Network interface card (NIC)
– usually circuitry built in- Add on slot on system board, USB port, notebook
PC slot
Client/Server – Why not both
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Client
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The user
Ask for information
Data sent to server
Server
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Responds to the user
(client)
Application server
Print server
Sends back data
Network topology
Star
Ring
Bus
Mesh
Tree
Hybrid
• Two types of topologies: Physical and Logical
•Physical topology of a network refers to the layout of
cables, computers and other peripherals
•network cables coming out of every computer that is
part of the network, then those cables plug into a hub or
switch
•Logical topology is the method used to pass the
information between the computers
•the network works with all the computers talking (think
of the computers generating traffic and packets of data
going everywhere on the network)
•computers will be talking to each other and the direction
of the traffic is controlled by the various protocols (like
Ethernet)
Star
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Reduces risk of failure.
Expanding the network
is simple.
Managing the network is
centralized.
If the hub breaks down,
the system fails.
Ring
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All clients have equal
access to data.
This gives even
performance under
heavy demand
conditions.
Difficult to add another
host to the ring.
Bus
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Simple, cheap, reliable,
efficient use of cable.
Isolating problems is
hard.
One error can halt the
system.
Mesh
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This redundancy allows
the system to continue if
some connections fail.
However, multiple
connections are
expensive.
Tree
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Point-to-point wiring for
individual segments.
Supported by several hardware
and software venders
Overall length of each segment
is limited by the type of cabling
used.
If the backbone line breaks, the
entire segment goes down.
More difficult to configure and
wire than other topologies
Hybrid – Star and Bus
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Network expansion is
simple.
If one client fails, the
entire network does not
fail.
If one hub fails, all
connections to that hub
fail, although other hubs
continue to function.
Devices
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Any electronic device that broadcast network data
Can include
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Hubs, links 2 or more nodes of wired network
Routers, ships data from one network to another
Switches, only sends data to specified destination
Gateways, used to join 2 networks using different protocols,
different address ranges
Bridges, connects 2 similar networks without regard to network
format
Repeaters
References
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Slide 11
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Slides12, 13, 14
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http://www.geocities.com/richard_leigh_bowles/theory/summaries/ntf/chap1.htm
Slide 15
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http://www.firewall.cx/topologies.php
http://chauncy-ict.pbwiki.com/Mesh%20Topology
Slide 16
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http://fcit.usf.edu/Network/chap5/chap5.htm#TreeNetwork