bit session 10 d.punia

8/3/2019 BIT Session 10 d.punia

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Basics of IT & MIS

Session 8-9

Dr. Devendra Kumar [email protected]

[email protected]


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Telecommunication

Transfer of meaningful information from sender to receiverover cable or wireless media

Includes all of the hardware and software necessary for itstransmission and reception

Telephony

Limited to transmission of sound over wire or wireless Assumes temporarily dedicated point-to-point connection

rather than broadcast connection

Telegraphy Limited to transmission of dash (long beep) and dot (short

beep) over wire or wireless

Distinction between Telecom and Telephony Difficult to distinguish because of the use of digital

techniques (binary bits) for transmitting any form ofinformation (audio, video or data)

What is telecommunication?


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History oftelecom: an overview 1837: Samuel Morse invents the telegraph

1858: Transoceanic telegraph cable is laid 1876: Alexander Graham Bell invents the telephone

1885: Incorporation of AT&T

1888: Hertz discovers the electromagnetic wave

1895: Marconi begins experimenting with wireless telegraph

1906: First radio built

1920: First commercial radio broadcast

1969: ARPANET was funded by the DARPA

1978: Unix-to-Unix copy program

1981: Development of CSNET and BITNET 1982: Term Internet is coined

1986: Establishment of NSFNET

1989: CSNET and BITNET merge to form CREN

1990: WWW becomes part of the Internet


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What is a Computer Network?

Figure 7-1, 7-2

Network Interface Card (NIC)

Hub, Switch, Router, Wireless Access Points

Server

Network Operating System (NOS)


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Networking & Communication trends

Separate voice and computer (data) networks

Merging of both

Telephone companies offering data services

Cable companies offering internet, data services

Computer networks supporting voice, video Broadband, 3G, wireless access laptop,

blackberry, mobile, bluetooth etc.


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Classification by Spatial Distance

LAN (Local Area Network) Less than 5 km, private, Mbps to Gbps

MAN (Metropolitan Area Network)

5 to 50 km, private/public, kbps to Mbps

WAN (Wide Area Network)

More than 50 km, private/public, kbps to Mbps

Classification of data networks


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Classification by Topology

Ring

Bus

Star

Tree

Mesh

Hybrid



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By SwitchingTechnology

Circuit Switching Connection-oriented networks, ideal for real-time applications,

guaranteed quality of service

Message Switching Store-and-forward system

Packet Switching Shared facilities, Used for data communications



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Type ofInformation

Data Communications Digital transmission of information

Voice Communications

Telephone communications

Video Communications

Cable TV or video conferencing



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By Computing Model

Distributed Computing Client/Server set-up

Centralized Computing

Thin-client architecture



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By Ownership

Public Network Owned by a common carrier

Private Network

Built for exclusive use by a single organization

Virtual Private Network

Encrypted tunnels through a shared private or publicnetwork



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Is a set of rules used for communications

between entities in a system

Entities

User applications

e-mail facilities terminals

Systems

Computer

Terminal Remote sensor

Local Area Networks - protocol


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a human protocol and a computer network protocol

Hi

Hi

Whats the

time?8:00pm

TCP connectionreq.

TCP connectionreply.

Get http://gaia.cs.umass.edu/index.htm

time

What is a protocol?

Time forbreak?

Lets gofor break!

specific msgs sent

specific actions taken when msgsreceived, or other events

protocols define format, order of msgs sent and received among networkentities, and actions taken on msg transmission, receipt


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Key elements of a protocol

Syntax

Data formats

Signal levels

Semantics

Control information Error handling

Timing

Speed matching

Sequencing

Protocols are standards that

specify how data is representedwhen being transferred fromone machine to another

Protocols specify how the

transfer occurs, how errors aredetected, and howacknowledgements are passed

Layered Protocols are designed so that layer n at the destination receivesexactly the same object sent by the layer n at the source.


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User Layer

Application Layer

Computer (Transport) Layer

Transmission Layer

Layered communication


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TCP / IP Protocol


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Peer to Peer networking


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Node to Node delivery


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Exchange using Internet


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The Physical Layer

The physical layer is responsible for transmitting individual bitsfrom one node to the next.


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Data LinkLayer

The data link layer is responsible for transmitting frames fromone node to the next.


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NetworkLayer

The network layer is responsible for the delivery of packets fromthe original source to the final destination.


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Transport Layer

The transport layer is responsible for delivery of a message fromone process to another.


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Application Layer

The application layer is responsible for providing services to theuser.


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Summary of layers functions


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Signals Analog vs Digital

Examples


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Local Area Networks

A group of computers & associated devices that share

a common communications line / wireless link andtypically share the resources of a single processor orserver within a small geographic area (e.g. within anoffice building / campus).

Usually, the server has applications and data storage

that are shared in common by multiple computerusers.

A local area network may serve as few as two orthree users (for example, in a home network) ormany as thousands of users.

Features Smaller scope, a building or a small campus

Usually owned by same organization as attached devices

Data rates much higher

Usually broadcast systems


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Source: http://homenethelp.com/home-network.asphttp://danbricklin.com/homenetwork.htm

Local Area Networks sample config


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Source: http://www.internalauditing.mnscu.edu/NetworkSecurity/FEBCONFB.PDF



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Source: http://www.uccs.edu/~is681/data_signals_w2.ppt



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Local Area Networks - characteristics

Topology

The geometric arrangement of devices on the networkor the shape of a local-area network (LAN) or othercommunications system.

Media Devices can be connected by twisted-pair wire, coaxial

cables, or fiber optic cables. Some networks do without

connecting media altogether, communicating instead viaradio waves

Hardware A number of hardware devices are used to implement LAN.These devices provide connectivity with in a single LAN orinterface with other LANs / Networks.

Protocols The rules and encoding specifications for sending data. The

protocol defines the format and meaning of the data that isexchanged. The protocols also determine whether thenetwork uses a peer-to-peer or client/server architecture.


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Local Area Networks - topology

Ring

Bus Star

Tree

Mesh

Hybrid


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Local Area Networks - media

Electrical (Copper)

Coaxial Cable Single copper conductor in the centre surrounded by a plastic

layer for insulation and a braided metal & plastic outer shield

Twisted Pair

Four pairs of wires twisted to certain specification

Fiber Optic A cable consisting of a center glass core surrounded by layers

of plastic that transmits data using light rather thanelectricity

Wireless (Atmosphere)

Makes use of electromagnetic waves.

Criteria for media selection

Distance and location limitations, wiring configurations,speed, reliability, security, budget


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Source : http://depts.washington.edu/sacg/facilities/workshops/networking/network_adv/hardware.shtml

Local Area Networks media (Copper)

Coaxial Cable

Widely used in LAN initially, now widelyused in cable TV, radio equipment

Twisted Pair

CAT5

Ethernet cable standard defined by the

Electronic Industry Association and TheIndustry Association (EIA/TIA)

Speeds upto 100 Mbps

DSL (Digital Subscriber Line) (Broadband)

High speed (256 Kbps 55 Mbps), full-

duplex Connector

RJ45 Standard connectors used forunshielded twisted pair cable


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Local Area Networks media (Fiber)

Fiber Optic

Infrared light is transmitted throughfiber and confined due to totalinternal reflection

Fibers are made out of either glassor plastic

Used for high speed backbones andpipes over long distances

Comparatively expensive


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Source : http://fcit.usf.edu/network/glossary.htm

Local Area Networks media specification

Ethernet

10BaseT Ethernet specification for unshielded twisted pair cable (category

3, 4 or 5), transmits signals at 10 Mbps with a distance limit of100 meters per segment

10BaseF

Ethernet specification for fiber optic cable, transmits signals at10 Mbps with a distance limit of 2000 meters per segment

100BaseT

Ethernet specification for unshielded twisted pair cable,transmits signals at 100 Mbps with a distance limit of100meters per segment

1000BaseTX

Ethernet specification for unshielded twisted pair cable,transmits signals at 1 Gbps with a distance limit of 220 metersper segment


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Local Area Network - Ethernet

The most widely used LAN hardware.

Developed originally in 1980 as 10 Mbps (10 millionbits per second) by Digital, Intel and Xerox

Today, the mainstream Ethernet is known as FastEthernet (100 Mbps) which uses HUB and Category

5 UTP wiring Also Gigabit Ethernet (1000 Mbps) is available but

limited in distance.

The Ethernet card is responsible for framegeneration and reception

An Ethernet frame encapsulates a network layerpacket

Ethernet encompasses Data-Link Layer and PhysicalLayer


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Hub An unintelligent network device that sends one

signal to all of the stations connected to it. All computers/devices are competing for attention

because it takes the data that comes into a portand sends it out all the other ports in the hub.

Traditionally, hubs are used for star topologynetworks, but they are often used with otherconfigurations to make it easy to add and removecomputers without bringing down the network.

Resides on Layer 1 of the OSI model

Switch Split large networks into small segments,

decreasing the number of users sharing the samenetwork resources and bandwidth.

Understands when two devices want to talk toeach other, and gives them a switchedconnection

Helps prevent data collisions and reduces networkcongestion, increasing network performance.

Most home users get very little, if any, advantagefrom switches, even when sharing a broadbandconnection.

Resides on Layer 2 of the OSI model.

Source: http://www.practicallynetworked.com/networking/bridge_types.htmhttp://handsonhowto.com/lan102.html

Local Area Networks - hardware


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Bridge Connects two LANs and forwards or filters data packets

between them. Creates an extended network in which any two

workstations on the linked LANs can share data. Transparent to protocols and to higher level devices like

routers. Forward data depending on the Hardware (MAC) address,

not the Network address (IP).


Repeater Used to boost the signal between two cable segments or

wireless access points. Can not connect different network architecture.

Does not simply amplify the signal, it regenerates thepackets and retimes them. Resides on Layer 1 of the OSI model.




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Router A device that connects any number of LANs. Uses standardized protocols to move packets efficiently to

their destination.

More sophisticated than bridges, connecting networks ofdifferent types (for example, star and token ring)

Forwards data depending on the Network address (IP), not

the Hardware (MAC) address. Routers are the only one of these four devices that will allow

you to share a single IP address among multiple networkclients.





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Additional Network Hardware Devices Network Interface Cards (NICs)

Puts the data into packets and transmits packet onto the network.

May be wired or wireless.

Gateway

Connects networks with different protocols like TCP/IP network and IPX/SPX networks.

Routers and Gateways often refer to the same device.

Proxy server Isolates internal network computers from the internet.

The user first access the proxy server and the proxy server accesses the internet andretrieves the requested web page or document. The user then gets a copy of that pagefrom the proxy server.

Source: http://www.camas.wednet.edu/chs/tech/computer_tech/info/routers_hubs_bridges.htm



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Wireless LAN (WLAN)


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Wireless LANs A local area network that transmits over the air typically in an

unlicensed frequency such as the 2.4GHz band.

A wireless LAN does not require lining up devices for line ofsight transmission.

Wireless access points (base stations) are connected to an

Ethernet hub or server and transmit a radio frequency overan area of several hundred to a thousand feet which canpenetrate walls and other non-metal barriers.

Roaming users can be handed off from one access point toanother like a cellular phone system.

Laptops use wireless network cards that plug into an existingPCMCIA slot or that are self contained on PC cards, whilestand-alone desktops and servers use plug-in cards (ISA,PCI, etc.).

Source: http://www.dslreports.com/faq/2262


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Source : http://en.wikipedia.org/wiki/Wireless_LAN

Wireless LAN orWLANWireless local area network that uses radio wavesas its carrier

Wi-Fi ("Wireless Fidelity)A set of standards forWLANs based on IEEE 802.11

Wi-MaxEmerging technology that can cover ranges up to 10miles or more

Satellite/MicrowaveHigh speed media used for longer distances andremote locations

Wireless LAN media


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Wide Area Network (WAN)


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Wide Area Networks

Large geographical area

Crossing public rights of way

Rely in part on common carrier circuits

Alternative technologies

Circuit switching Packet switching

Frame relay

Asynchronous Transfer Mode (ATM)


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Circuit Switching

Dedicated communications path established

for the duration of the conversation e.g. telephone network


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Packet Switching

Data sent out of sequence

Small chunks (packets) of data at a time

Packets passed from node to node betweensource and destination

Used for terminal to computer and computerto computer communications


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Frame Relay

Packet switching systems have large

overheads to compensate for errors Modern systems are more reliable

Errors can be caught in end system

Most overhead for error control is stripped out


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Asynchronous Transfer Mode (ATM)

Evolution of frame relay

Little overhead for error control

Fixed packet (called cell) length

Anything from 10Mbps to Gbps

Constant data rate using packet switchingtechnique


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Mobile &wireless computing


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Multiplexing

In a mobile and wireless network, the

wireless medium is shared by many nodes.

Hence, multiple use of a shared medium is amajor challenge in wireless networking.

Most decisions for accessing the wirelessmedium is made in the MAC layer.

The wireless channels can be multiplexed(used by multiple machines) in fourdimensions : Space (s) Time (t)

Frequency (f) Code (c)

l l ll l k


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Space multiplexing : Cellular Networks

Same frequency can be

reused when the basestations are separatedin space.

The reuse of frequenciesdepend on signal

propagation range.

Example : fixedfrequency assignmentfor reuse with distance2.

F Di i i l i l (FD )


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FrequencyDivision Multiplex (FDM)

The whole spectrum is

separated into smallerfrequency bands.

A band is allocated to achannel for the wholetime.

This is somewhatinflexible if the traffic isnon-uniform.

An example is radio orTV broadcast. The

bandwidth is wasted if astation is off the air.

t

f

Ti Di i i M l i l (TDM)


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Time Division Multiplex (TDM)

A channel gets the

whole frequencyspectrum for a certainamount of time.

Only one user for themedium at a time.

Usually the throughputis high even with manyusers.

However, no two usersshould use the medium

at the same time.Precise synchronizationis needed. t

f

C d Di i i M l i l (CDM)


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Code Division Multiplex (CDM)

Each channel uses a

unique code fortransmitting.

All channels use the

same frequencyspectrum at the sametime.

However, signalregeneration is verycomplex and requirescomplex HW/SWsupport.

f

t

c


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The Internet

Th I


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The Internet

The Internet is a network of networks.

Today, the Internet connects tens ofthousands of networks and millions ofcomputer

1990: 3000 networks ( 200,000 users.)

1992: 992,000 hosts.

Present: millions of networks, computers,and users.


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N i d Add i


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Naming and Addressing

Uniquely identify processes in different

computers for communications. IP address

Domain name

Port number

MAC address

IP Add


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IP Address

Each host interface in the Internet has a

unique IP address. IPv4, 32 bits, dotted-decimal notation

IPv6, 128-bit address

Fi Cl f IP Add


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Five Classes of IP Addresses

S b tti


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Subnetting

Three levels of an IP address:

Network ID

Subnet ID

Host ID

Subnet mask: separates subnet ID and host ID

A i d b A h i ( A A)


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Internet Assigned Numbers Authority (IANA)

Internet Assigned Numbers Authority (IANA) is

responsible for three things: Assigning IP addresses, that is, the four octets to identifyevery Internet router, server and workstation

Running the root name servers that provide the essentialbase for the Domain Name System (DNS)

Acting as final arbiter and editor for key standards developed

by the Internet Community IANA developed the Dotted Decimal Notation

A technique used to express IP addresses via the use of fourdecimal numbers separated from one another by decimalpoints

Oth M j t d d b di


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Other Major standards bodies ISO (International Organization for Standardization)

Technical recommendations for data communication interfaces

Composed of each countrys national standards orgs.

Based in Geneva, Switzerland (www.iso.ch)

ITU-T (International Telecommunications Union Telecom Group Technical recommendations about telephone, telegraph and data

communications interfaces

Composed of representatives from each country in UN Based in Geneva, Switzerland (www.itu.int)

ANSI (American National Standards Institute) Coordinating organization for US (not a standards- making body)

(www.ansi.org)

IEEE (Institute of Electrical and Electronic Engineers)

Professional society; also develops mostly LAN standards,http://standards.ieee.org

IETF (Internet Engineering Task Force) Develops Internet standards

No official membership (anyone welcome) (www.ietf.org)

IP i (IP 6)


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IP version (IPv6) IP version 6 (IPv6) has been developed to extend

source and destination addresses and provide amechanism to add new operations with built-insecurity

Although IPv4 is still widely used, over the next fewyears, the IPv4 32-bit address will be replaced with

the IPv6 128-bit address

Slow adoption of IPv6 is attributed to the enormousdifficulty in changing network-layer protocols

Domain Name


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Domain Name

Identify a host

User friendly Hierarchically organized

Domain Name System (DNS): resolves a domainname to the corresponding IP address.

DNS servers and the domain name database Name caching

DNS query and reply

The Domain Name Space


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The Domain Name Space

Port Number


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Port Number

Address for the application layer user

process. Port Number field in TCP or UDP header.

Well-known port numbers 1 to 255: Internet wide services

256 to 1023: preserved for Unix specific services 1024 and up: ephemeral port numbers

MAC address


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MAC address

used to get datagram from one interface to another

physically-connected interface (same network) 48 bit MAC address (for most LANs) burned in the

adapter ROM

MAC address allocation administered by IEEE

Manufacturers buy portion of MAC address space (toassure uniqueness)

Each adapter has a

unique MAC address

Internet Services


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Internet Services

Email, Instant messaging, Chat

World Wide Web Flie Transfer, Telnet

VoIP

Voice o er IP (VoIP)


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Voice over IP (VoIP) VoIP is transmitting telephone calls over the Internet

rather than through the traditional telephone system

PSTN and IP Internetworking Assured Quality Routing (AQR) marries packet and circuit

switching to automatically reroute calls to the PSTN whenparameters do not meet accepted ranges

VoIP Call Process

VoIP QoS Jitter buffer discards and bursts (varying periods of packet

loss), are concealed by PLC-enabled vocoders

Virtual Private Network (VPN)


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Virtual Private Network (VPN)

VPNs are encrypted tunnels through a shared private

or public network, and are very cost-effective ascompared to dedicated or leased lines.

Tunneling is the process of encrypting and thenencapsulating the outgoing information in IP packets fortransit across the Internet and reversing the process at the

receiving end. Encryption involves scrambling of data by use of a

mathematical algorithm.

VPN Tunnels and Protocols


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VPN Tunnels and Protocols LAN-to-LAN or site-to-site tunnels

Usually corporate environments, where users on either LAN

can use the tunnel transparently to communicate with oneanother

Client-to-LAN tunnels Need to be set up, so the client must run special software to

initiate the creation of a tunnel and then exchange trafficwith the corporate network

Virtual Private LAN Service (VPLS) A class of VPN that connects multiple sites over a managed

IP/MPLS network to form a single bridged domain

VPN Protocols Leading protocols are: PPTP, L2TP, and IPSec

Internet2 Web 2 0 Web 3 0


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Internet2, Web 2.0, Web 3.0

Internet2 is an outcome of collaborative

efforts to address the increasing need forgreater bandwidth and sustaining a cutting-edge network capability

I2 helps to alleviate traffic jams through thecreation of a limited number of regional hubs,called Giga-POPs, which serve as accesspoints for high-performance networks

Intranet & Extranet


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Intranet & Extranet

Intranet A LAN that uses the Internet technologies within an

organization

Open only those inside the organization

Example: insurance related information provided toemployees over an intranet

Extranet A LAN that uses the Internet technologies across an

organization including some external constituents

Open only those invited users outside the organization

Accessible through the Internet

Example: Suppliers and customers accessing inventoryinformation in a company over an extranet

Converged Networks


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Converged Networks Converged Data/Voice networks

Application of voice digitization and compression techniques

to enable voice transmission over networks originallydeveloped to transport data

Characteristics of Converged Data/Voice Networks Low delay, Echo cancellation, Latency and Jitter for voice

Call-completion ratio Intelligent network services like AA, caller ID, hunt groups Interface with standard telephone sets Handle megabit data streams for video Low error rates for data Strong security for mission-critical data

Wireless Computing Networks


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Wireless Computing Networks

Bluetooth

Wi-Fi Wi-Max

RFID &Sensor networks


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HTTP

Hyper Text Transfer Protocol (HTTP)


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Hyper Text Transfer Protocol (HTTP) This is the Webs application protocol, operates on the client-

Server model. The client and server executing on different end-

systems communicate using HTT

P messages.

Also a HTTP dialogue may be concerned with transferring severalfiles associated with a particular web page. Generally a baseHTML file and the files relating to several referenced objects.

Persistent and non persistent connections

Uniform Resource Locator

protocol (http, ftp, news)

host name (name.domain name)

port (usually 80) directory path to the resource

resource name

http://mail.yahoo.com/

Non-Persistent HTTP


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TCPConnect.Rq

Request File

Send File

Disconnect.Rq

Connect.Rq

Non Persistent HTTP

Persistent HTTP


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Connect.Rq

Request File

Disconnect.

Rq

Request File

Request File

Send File

Send File

Send File

Persistent HTTP

Pervasive networking


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Pervasive networking

Means Networks will be everywhere

Exponential growth of network use Many new types of devices will have network

capability

Exponential growth of data rates for all kinds of

networking Broadband communications

Use circuits with 256 Kbps or higher (e.g., DSL)

Integration of voice video & data


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Also called Convergence Networks that were previously transmitted using separate

networks will merge into a single, high speed, multimedianetwork in the near future

First step largely complete Integration of voice and data

Next step Video merging with voice and data

Will take longer partly due to the high data rates required for

video

Integration of voice, video & data

New information services


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New information services

World Wide Web based

Many new types of information services becoming available Services that help ensure quality of information received over

www

Application Service Providers (ASPs)

Develop specific systems for companies such as providing

and operating a payroll system for a company that does nothave one of its own

Information Utilities (Future of ASPs)

Providing a wide range of info services (email, web, payroll,etc.) (similar to electric or water utilities)

Implications for management


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Implications for management

Embrace change and actively seek to use newaspects of networks toward improving yourorganization Information moved quickly and easily anywhere and anytime

Information accessed by customers and competitors globally

Use a set of industry standard technologies Can easily mix and match equipment from different vendors

Easier to migrate from older technologies to newertechnologies

Smaller cost by using a few well known standards

Network Design Triangle


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Policy

ArchitectureProtocols

Security

$$$ Cost $$$

Mobility Scalability

Maturity

BandwidthQoS

2004 Syzygy Engineering W ill Ivancic

NetworkDesign Triangle


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Thanks

bit session 10 d.punia

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