Transcript computer_networks

Computer networks
Internet, Intranet, Extranet, Lan,
Wan, characteristics and
differences.
Paweł Madera
Table of Content
1. Generally about Computer Network
2. Network Classification
3. Types of Networks
4. Network Hardware Componenets
5. Local Area Network (LAN)
1.Ethernet
2.Star Topology
3.Mesh networking
4.Wireless Network: Wi-Fi
6. Wide area network
Table of Content
1. Internet
1.TCP Protocol
2.Packet/Switching
3.Client/Server Networking
4.Internet Functions
2. Intranet
3. Extranet
4. LAN & WAN comparison
5. Intranet & Extranet comparison
Generally about Computer
Network…
• group of interconnected computers
• allows computers to communicate
• share resources and information
Network Classification
Types of Networks
Network Hardware Componenets
Local Area Network (LAN)
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small geographic area (e.g. room, office)
contrast to wide-area networks (WANs)
controlled by one administrative authority
usually high speed
always shared
Ethernet
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developed by Xerox in 1973–1975
standardized as IEEE 802.3
has replaced token ring, FDDI and ARCNET
usually uses twisted pair cable ( RJ-45)
Star Topology
• one of the most common
• hub accepts data from a sender and delivers it to the
receiver
• reduces the chance of failure by connecting to a central
node
• good performance - passing the Data through
unnecessary nodes is prevented
Mesh networking
• continuous connections around blocked paths by
“hopping” from node to node until the destination
is reached.
• can still operate even when a node breaks down
• Wi-Fi mesh is typical
Wireless Network: Wi-Fi
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cheap networking solution
radio waves instead of cables
three standards :
802.11a, 802.11b and 802.11g
2 modes – Infrastructure, and Ad-hoc
Hotspots – easy internet access
Wide Area Network (WAN)
• computer network that covers a broad area
• crosses metropolitan, regional, or national
boundaries
• uses routers and public communications links
• Example: Internet
Wide Area Network (WAN)
• used to connect LANs and other types of
networks together
• Option for WAN connectivity
1. Leased Line
2. Circuit switching
3. Packet switching
4. Cell relay
• Speed from 1200 bits/s to 6 Mbit/s
Wide Area Network (WAN)
• Turning into VPN to interconnect their networks,
in that way
Internet
• Vision Appeared first in a 1946 comic
science-fiction story “A Logic Named Joe”
• SAGE program connecting, radar systems
• On August 6, 1991, CERN, straddled the
border between France and Switzerland
• During the 1990s, it was estimated grew
by 100% per year, with boom in 1996 and
1997
Internet
• global system of interconnected computer
networks
• consists of millions of private and public
networks
TCP Protocol
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TCP= Transmission Control Protocol
Developed by US Department of Defense in 70s
Set of network rules
4 layers structure
IP protocol
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provides addressing for computers
IP Version 4 is the initial version
~4.3 billion (109) Internet hosts
IP v6 provides vastly larger addressing
capabilities
• IPv6 will be not compatible with IPv4
Packet/Switching
• Slicing digital message into
packets (parcels)
• Size of a packet = 128 bytes
(X.25)
• Security of the data
Client/Server Networking
• Model of networking
• Balanced architecture
• one or more Server
Computers
• Example: Internet
Internet Functions
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E-mail
File-sharing
Instant messaging
Internet fax
World Wide Web
Voice over IP
Mobile VoIP
Intranet
• Private computer network
• secure sharing organization's information or operational
systems with its employees.
• The same architecture as in Internet
• private version of the Internet
Intranet
• possible access to the Internet, then geteway with
firewall is applied
• Intranet delivers
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tools and applications,
collaboration (to facilitate working in groups and teleconferencing)
sophisticated corporate directories
sales and Customer relationship management tools
project management etc
• In large intranets, traffic is often similar to public website
traffic
Extranet
• Uses Internet protocols, network connectivity
• Share informations as intranet
• The number of clients is extended to people
outside the company
• interconnections are over a shared network
rather than through dedicated physical lines as in
intranet
LAN & WAN comparison
LAN
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Small area covered
Use public communication links
Usually low speed
Uses Wi-Fi, Ethernet cables
WAN
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Large area area covered
Use public communication links
Usually fast speed
Uses optic wires, microwaves,
satellites
Intranet and Extranet comparison
Intranet
• connects users in
company
• shared network
• single company's
administrator
• Don’t need so much
security
Extranet
• connects user inside
and outside company
• Dedicated physical lines
• multiple company's
administrator
• Requires more securtity
The End