Transcript intro to Networking

Computer Networks – an
overview
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Computer Networks
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Advantages of a network
Client/server and peer-to-peer
networks
Classifications of client/server
networks
Client/server network components
Types of servers
Network topologies
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Topics
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Types of transmission media
Network software
Network adapters
Moving data in a client/server
network
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Networking Advantages
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Networks:
• Increase productivity
• Enable the sharing of resources
• Facilitate Internet connectivity
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Client/Server Networks
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Server based network:
• Clients
• Servers
Data flows efficiently
Servers respond to
requests from clients
Servers perform
specific tasks
Scalable network
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Classifications of Client/Server
Networks
 LAN:
• Local area network
• Computers linked together over a small
geographic region
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WAN:
• Wide area network
• Computers linked together over large
diverse geographic locations
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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
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PAN:
• Personal area network
• Wireless devices connected in close
proximity to each other
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Intranet:
• Private corporate network
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Constructing Client/Server
Networks
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Servers
Network topologies
Transmission media
Network operating system (NOS)
Network adapters
Network navigation devices
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Servers
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Number and type of servers depend
on network size and workload
Dedicated server:
• Perform one specific function
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Authentication server:
• Keeps track of network logins and
services available
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File server:
• Store and manage files
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Dedicated
Servers
Print server:
• Manages client-requested printing jobs
• Creates print queue (prioritizes print jobs)
Applications server:
• Acts as a storage area for application software
Database server:
• Provides clients with access to database
information
E-mail server:
• Process and deliver in-coming and outgoing email
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Dedicated Servers
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Communications server:
• Handles communications between
networks including the Internet
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Web server:
• Hosts a Web site available through the
Internet
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Network Topologies
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The physical layout of computers,
transmission media, and other
components
Types of network topologies include:
• Bus topology
• Ring topology
• Star topology
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Bus Topology
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All nodes are connected
in sequence on a single
cable
Used most often on
peer-to-peer networks
Networked computers
communicate with each
other
One computer transmits
data at a time:
• Access methods avoid
data collisions
• Data is transmitted in
“packets”
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Ring Topology
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Nodes are laid out
in a ring
Token (data
packet) flows in
one direction from
device to device
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Star Topology
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Nodes connect to a
central
communications
device (hub/switch)
A node sends a
signal to the hub
which retransmits it
to the other nodes
A node accepts the
signal addressed to it
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Avoiding Data Collisions on a
Star Network
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Transmission Media
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The routes data takes to flow
between devices on a network:
Wired
Wireless:
• Wireless Fidelity (Wi-Fi)
• Uses radio waves
• 802.11 standard
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Choosing a Cable
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Maximum run length
Bandwidth
Bend radius
Cable cost
Installation costs
Susceptibility to interference
Signal transmission methods
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Twisted Pair Cable
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Pairs of copper wire twisted around
each other
Twists make the wires less
susceptible to interference
Shielded twisted pair (STP)
• Layer of foil shielding
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Unshielded twisted pair (UTP)
• Cat 5E
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Bandwidth 1Gbps
• Cat 6
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Bandwidth 200 Mbps
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Coaxial Cable
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Four components:
• Copper core
• Nonconductive insulating material
• Braided metal
• Plastic cover
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Fiber-Optic Cable
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Components include:
• Glass or plastic fibers
• Cladding
• Outer jacket
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Uses light impulses to transmit data
Immune to interference
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Network Operating Systems
(NOS)
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Provide the protocol that controls the
communication between devices on
the network
Major network operating systems:
• Windows Server XX
• UNIX
• Novell NetWare
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Network Adapters
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Devices that enable computers to
communicate on a network
Network interface cards (NICs):
• Generate network transmission signals
• Create data packets
• Act as information gatekeepers
• Ethernet compliant
• Wireless NICs
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Network Navigation Devices
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Media Access Control (MAC) address:
• Six 2-digit numbers (01:40:87:44:79:A5)
• Physical address of network adapter
• Internal network identification
Repeaters and Hubs:
• Amplify signals and retransmit them
Switches and Bridges:
• Send data on a specific route through the
network
• Bridges send data between collision domains
Routers:
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• Send information between two networks