Transcript Session5-Group4-Networking

Networking & the
Internet
What is a Network?
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A computer network allows computers to communicate
with many other computers and to share resources and
information.
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Connection Method
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Wired
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Twisted Pair Cables
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Fiber Optics, ...
Wireless
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Wireless LANs
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Bluetooth
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Cellular System, ...
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Scale
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Local Area Network (LAN)
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◊
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Typically have a single moderator
Wide Area Network (WAN)
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a computer network covering a small physical area, like a
home, office, or small group of buildings
a data communications network that covers a relatively
broad geographic area
Typically have multiple moderators and owners
...
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Network Topology
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physical interconnections of the elements (links, nodes,
etc.) of a computer network
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What is Internet
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It is a network of networks that consists of millions of
private and public, academic, business, and government
networks of local to global scope that are linked by
copper wires, fiber-optic cables, wireless connections,
and other technologies
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How networks work?
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Application
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Presentation
HTTP, IRC, FTP, SSH, …
Application
Presentation
Browser, Chat, Game, Multimedia, …
Language, …
Not used !
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Session
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Transport
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Network
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1
Link
Physical
Session
TCP, UDP
IP
Ethernet
Wire,
Radio,
Optic, …
Transport
Network
Network
Link
Link
Physical
Physical
Who said what?
End-to-End, Error Recovery, …
Finding where to send, Naming, …
Hop-by-Hop, Managing Physical Link
Encoding Signal, …
Internet Protocol(IP)
Provides addressing systems (IP addresses) for computers
on the Internet
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IP Version 4 (IPv4) – e.g. 192.168.0.2
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the initial version used on the first generation of the
today's Internet and is still in dominant use. It was
designed to address up to ~4.3 billion Internet hosts.
However, the explosive growth of the Internet has led
to IPv4 address exhaustion which is estimated to
enter its final stage in approximately 2011.
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Internet Protocol(cont'd)
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IPv6 – e.g. ::ffff:192.0.2.128
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A new protocol version, IPv6, was developed in the
mid 1990s which provides vastly larger addressing
capabilities and more efficient routing of Internet
traffic. It allows for 3*1038 addresses.
Application
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IPv6 is currently in commercial deployment
phase around the world.
Presentation
Session
Transport
Network
Link
Physical
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Port
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A port is an application-specific or process-specific
software construct serving as a communications
endpoint
Application
Presentation
Session
Transport
Network
Link
Physical
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Uniform Resource Locator (URL)
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A string of characters used to specify where an identified
resource is available and the mechanism for retrieving it.
e.g.
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http://ce.sharif.ir
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ftp://cabinet.ce.sharif.edu/
Application
Presentation
Session
Transport
Network
Link
Physical
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Protocol
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In computing, a protocol is a set of rules which is used
by computers to communicate with each other across a
network. A protocol is a convention or standard that
controls or enables the connection, communication, and
data transfer between computing endpoints. In its
simplest form, a protocol can be defined as the rules
governing the syntax, semantics, and synchronization of
communication
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Famous Protocols
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HTTP(Hypertext Transfer Protocol)
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FTP(File Transfer Protocol)
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SMTP(Simple Mail Transfer Protocol)
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POP3(Post Office Protocol) /
IMAP(Internet Message Access Protocol)
HTTPS/SFTP/SMTPS/POP3S/IMAPS (Secure)
Application
Presentation
Session
Transport
Network
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Telnet host port (e.g. telnet ce.sharif.edu 22)
Link
Physical
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Basic Hardware Components
All networks are made up of basic hardware building
blocks to interconnect network nodes.
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Basic Hardware Components
(Nodes & Building Blocks)
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PCs & Servers
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Network card
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Cables
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Hubs
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Switches
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Routers
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Basic Hardware Components(cont'd)
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Clients(PCs) & Servers
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Network card
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a Media Access Control address (MAC address)
is a unique identifier assigned to most network
adapters or network interface cards (NICs) by
the manufacturer for identification. If assigned
by the manufacturer, a MAC address usually
encodes the manufacturer's registered
identification number
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Basic Hardware Components(cont'd)
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Hubs
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When a packet arrives at one port(connected cable),
it is copied unmodified to all ports of the hub for
transmission
Switches
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A network switch is a device that forwards and filters
chunk of data communication between ports based on the
MAC addresses in the packets
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Basic Hardware Components(cont'd)
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Routers
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A router is a networking device that forwards packets
between networks using information in protocol
headers and forwarding tables to determine the best
next router for each packet
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Networking Commands
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Ping google.com -t → Ctrl-C
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Nslookup google.com
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Tracert google.com (linux: traceroute)
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Ipconfig (linux: ifconfig)
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Whois
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WHOIS (pronounced as the phrase who is) is a
query/response protocol that is widely used for querying
databases in order to determine the registrant or
assignee of Internet resources, such as a domain name,
an IP address block, or an autonomous system number.
Whois sharif.edu
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Any Questions?
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