Download Technology in Action Network Topics Networking Advantages Client

8/4/2009
Network Topics
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Technology in Action
Behind the Scenes:
Networking
g and Security
y
© 2007 Prentice-Hall, Inc.
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Advantages of business networks
Client/server vs. peer
peer--toto-peer networks
Classifications of client/server networks
Client/server network components
Types of servers
Network topologies
Types of transmission media
Network software
Network adapters
Moving data in a client/server network
Securing networks
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Networking Advantages
Client/Server Networks
• Server
Server--based network
• Networks
– Clients and servers
– Increase productivity
– Enable the sharing of
h d
hardware
resources
– Enable the sharing of
software
– Facilitate Internet
connectivity
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• Data flows efficiently
• Servers respond to
requests from clients
• Servers perform
specific tasks
• Scalable network
• Centralized
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Classifications of
Client/Server Networks
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Classifications of
Client/Server Networks
• WAN
• LAN
– Wide area network
– Computers linked
over large
geographic
locations
– Local area network
– Computers linked
together over a
small geographic
region
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• MAN
– Metropolitan area
network
– Computers linked
together within a
city or county
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Classifications of
Client/Server Networks
Constructing
Client/Server Networks
• PAN
– Personal area network
– Wireless devices connected in close proximity
to each other
• Intranet
– Private corporate network
– Protected by a firewall
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Dedicated Servers
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Servers
Network topologies
Transmission media
Network operating
system (NOS)
• Network adapters
• Network navigation
devices
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Dedicated Servers
• Print server
• Number and type of
servers depend on
network size and
workload
• Dedicated server
– Manages client
client--requested printing jobs
– Creates print queue (prioritizes print jobs)
• Applications server
– Acts as a storage area for application software
– Performs one specific
function
• Database server
– Provides clients with access to database
information
• Authentication server
– Keeps track of network
logins and services
available
• E-mail server
– Processes and delivers in
in--coming and outgoing
e-mail
• File server
– Stores and manages files
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Dedicated Servers
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Network Topologies
• Communications server
• The physical layout of computers,
transmission media, and other
components
• Types of network topologies
– Handles communications between networks
including the Internet
– Often the only device on the network directly
connected to the Internet
– Bus topology
– Ring topology
– Star topology
– Hybrid topology
• Web server
– Hosts a Web site available through
the Internet
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Bus Topology
Ring Topology
• All nodes are connected in
sequence on a single cable
• Used most often on
peer--topeer
to-peer networks
• Networked computers
communicate with each
other
• One computer transmits
data at a time
• Nodes are laid out in
a ring
• Token (data packet)
flows in one direction
f
from
device
d i tto device
d i
• Active topology
topology--each
node retransmits
token and data to
next node
– Access methods avoid data
collisions
– Data is transmitted in
“packets”
• Passive topology
topology--nodes do
not move data along
network
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Avoiding Data Collisions
on an Ethernet Network
Star Topology
• Nodes connect to a central
communications device
(switch)
g
to
• A node sends a signal
the switch, which
retransmits it to the
other nodes
• A node accepts only
signal addressed to it
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Transmission Media
Choosing a Cable
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• The routes data takes to flow between
devices on a network
• Wired
• Wireless
Wi l
• Installation costs
• Susceptibility to interference
• Signal transmission methods
Maximum run length
Bandwidth
Bend radius
Cable cost
Comparison of Characteristics of Major Cable Types
– Wireless Fidelity (Wi(Wi-Fi)
– Uses radio waves
– 802.11 standard
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Cable Characteristics
Twisted Pair (Cat 6)
Coaxial (ThinNet)
Coaxial (ThickNet)
Fiber Optic
Maximum
Run Length
328 feet (100 m)
607 feet (185 m)
1,640 feet (500m)
Up to 62 miles (100 km)
Bandwidth
1,000 Mbps
10 Mbps
10 Mbps
100 Mbps to 2 Gbps
Bend Radius
(Flexibility)
No limit
360 degrees/foot
30 degrees/foot
30 degrees/foot
Cable Cost
Very low
Low
Moderate
High
Installation Cost
Very low
Low
Slightly higher
than ThinNet
Most expensive because of
Installation training required
Susceptibility
to Interference
High
Low
Very low
None (not susceptible
to EMI and RFI)
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Twisted Pair Cable
• Pairs of copper wire twisted
around each other
• Twists make the wires less
susceptible to interference
• Shielded twisted pair (STP)
Coaxial Cable
• Four components
– Copper core
– Nonconductive insulating material
– Braided metal
– Plastic cover
UTP
– Layer of foil shielding
• Unshielded twisted pair (UTP)
– Cat 5E: Bandwidth 200 Mbps
– Cat 6: Bandwidth 1 Gbps
– No foil layer
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STP
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Wireless Media
802.11 Standard
Fiber--Optic Cable
Fiber
• Components include
• Wi
Wi--Fi, short for Wireless Fidelity
– Glass or plastic fibers
– Cladding
– Outer jacket
– 802.11b - first cost-effective wireless devices.
– 802.11a, 802.11g – bandwidth increased to 54
Mbps
– Super G -bandwidth to 108 Mbps
– 802.11n - will support higher throughput and
greatly increased range
• Uses light impulses
to transmit data
• Immune to
interference
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Network Operating Systems (NOS)
• Provide the protocol that
controls the communication
between devices on the
network
j network operating
p
g
• Major
systems
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Network Adapters
• Devices that enable computers to
communicate on a network
• Network interface cards (NICs)
• Three functions
– Generate network transmission
signals
– Create data packets
– Act as information gatekeepers
– Windows Server 2003
– UNIX
– Novell NetWare
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• Ethernet compliant
• Wireless NICs
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Network Navigation Devices
Network Navigation Devices
• Media Access Control
(MAC) address
• Switches and
Bridges
– Six 22-digit numbers
(01:40:87:44:79:A5)
– Physical address of
network adapter
– Internal network
identification
– Send data on a
specific route
through
g the network
– Bridges send data
between collision
domains
• Routers
• Repeaters and Hubs
– Send information
between two
networks
– Amplify signals and
retransmit them
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Network Security
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Network Security
• Authentication
• Firewalls
– User ID and password used to access the network
– Prevent access to the network by
unauthorized users
– Composed of software and/or hardware
– Screen and validate data packets
– Bastion host/proxy server
• Access privileges
– Enable access to certain network systems
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• Physical protection measures
– Restrict physical access to sensitive network
equipment
– Magnetic card readers
– Biometric access devices
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Network Firewall Layout
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Summary Questions
• What are the advantages of a business
network?
• How does a client/server network differ
from a p
peer-to
peerto--p
peer network?
• What are the different classifications of
client/server networks?
• What components are needed to construct
a client/server network?
• What do the various types of servers do?
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Summary Questions
Summary Questions
• What are the various network topologies?
• What types of transmission media are
used in client/server networks?
• What software needs to be running on
computers attached to a client/server
network?
• How do network adapters enable
computers to participate in a client/server
network?
© 2007 Prentice-Hall, Inc.
• What devices assist in moving data
around a client/server network?
• What measures are employed to keep
large networks secure?
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