acn - subject notes

7/27/2019 Acn - Subject Notes

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ADVANCE COMPUTER NETWORK

UNIT I

INTRODUCTION

Syllabus

Requirements, Network architecture, Networking principles, Network services and Layered architecture, Future

networks (Internet , AT , !a"le T#, $ireless % &luetooth, $i'Fi, $i'a, !ell phone)

1.1 Introducton

A network is a set o* devices (o*ten re*erred to as nodes) connected "y communication links+ A node can "e a

computer, printer, or any other device capa"le o* sending andor receiving data generated "y other nodes on thenetwork+

Network can classi*ied as

&y !ommunication odes- .imple, /al* 0uple and Full 0uple+

&y .cale - LAN, $AN, AN, 1AN etc

&y !onnection ethod- 1oint to 1oint or ultipoint ethod

&y Transmission edia - 2thernet, 3ptical Fi"er, $ireless

&y Network Topology - &us, star, Ring, esh Topology etc &y anagement ethod- 1eer'to'1eer or !lientserver &ased

1.! R"#ur"$"nts

The 4rst step is to identi*y the set o* constraints and requirements that in5uence network design+ &e*ore

getting started, however, it is important to understand that the epectations you have o* a network depend onyour perspective-

An application programmer would list the services that his application needs, *or eample, a guarantee

that each message the application sends will "e delivered without error within a certain amount o* time+

A network designer would list the properties o* a cost'e**ective design, *or eample, that network

resources are e**iciently utili6ed and *airly allocated to di**erent users+

A network provider would list the characteristics o* a system that is easy to administer and manage, *oreample, in which *aults can "e easily isolated and where it is easy to account *or usage+

R"#ur"$"nt 1% Conn"ct&ty

Network must provide connectivity among a set o* computers+ .ometimes it is enough to "uild a limited

network that connects only a *ew select machines+ In *act, *or reasons o* privacy and security, many private(corporate) networks have the eplicit goal o* limiting the set o* machines that are connected+ In contrast, other

networks (o* which the Internet is the prime eample) are designed to grow in a way that allows them the

potential to connect all the computers in the world+ A system that is designed to support growth to an ar"itrarilylarge si6e is said to scale+ 7sing the Internet as a model, this "ook addresses the challenge o* scala"ility+

Network connectivity occurs at many di**erent levels+ At the lowest level, a network can consist o* twoor more computers directly connected "y some physical medium, such as a coaial ca"le or an optical 4"er+ $e

call such a physical medium a link, and we o*ten re*er to the computers it connects as nodes+ 1hysical links are

sometimes limited to a pair o* nodes (such a link is said to "e point'to'point), while in other cases, more than

two nodes may share a single physical link (such a link is said to "e multiple'access)+$hether a given linksupports point'to'point or multiple'access connectivity depends on how the node is attached to the link+ It is

also the case that multiple'access links are o*ten limited in si6e, in terms o* "oth the geographical distance they

can cover and the num"er o* nodes they can connect+ I* computer networks were limited to situations in whichall nodes are directly connected to each other over a common physical medium, then networks would either "e

very limited in the num"er o* computers they could connect, or the num"er o* wires coming out o* the "ack o*


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each node would quickly "ecome "oth unmanagea"le and very epensive+ Fortunately, connectivity "etween

two nodes does not necessarily imply a direct physical connection "etween them8indirect connectivity may "eachieved among a set o* cooperating nodes+

R"#ur"$"nt !% Cost'E(("ct&" R"sourc" S)arn*

9iven a collection o* nodes indirectly connected "y a nesting o* networks, it is possi"le *or any pair o* hosts to

send messages to each other across a sequence o* links and nodes+ 3* course, we want to do more than support

:ust one pair o* communicating hosts8we want to provide all pairs o* hosts with the a"ility to echange

messages+ The question, then, is how do all the hosts that want to communicate share the network, especially i*they want to use it at the same time; And, as i* that pro"lem isn


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"y that application+ In other words, :ust as use a cloud to a"stractly represent connectivity among a set o*

computers, think o* a channel as connecting one process to another+

The common services provided "y the network are-

>) !onversational .ervices such as #oice, #ideo telephony?) .treaming .ervices like real time audio'video transmission and Television etc

@) Interactive .ervices like the $orld $ide $e"

) &est 2**ort .ervices such as ail trans*er, File Trans*er etc

The common services provided "y networks are Authentication services, 0irectory services, 0ynamic /ostcon*iguration .ervices (0/!1), 0omain Name .ervices (0N.), 2'mail .ervices and Network Access services

etc+

1.- N"tor/ Arc)t"ctur"0 N"tor/n* Prnc+l"s0 N"tor/ S"r&c"s and ay"r"d Arc)t"ctur"

A computer network must provide general, cost e**ective, *air, and ro"ust connectivity among a large num"er o*

computers+ As i* this weren


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provided at any given level o* the system, each providing a di**erent service to the higher layers "ut "uilding on

the same low'level a"stractions+ To see this, consider the two types o* channels, one provides a requestreplyservice and one supports a message stream service+ These two channels might "e alternative o**erings at some

level o* a multilevel networking system, as illustrated in Figure+

2*ur"% ay"r"d Syst"$s t) alt"rnat&" abstractons

7sing this discussion o* layering as a *oundation, we are now ready to discuss the architecture o* a networkmore precisely+ For starters, the a"stract o":ects that make up the layers o* a network system are called

protocols+ That is, a protocol provides a communication service that higher'level o":ects (such as application

processes, or perhaps higher'level protocols) use to echange messages+ For eample, we could imagine anetwork that supports a requestreply protocol and a message stream protocol, corresponding to the

requestreply and message stream channels discussed a"ove+ 2ach protocol de4nes two di**erent inter*aces+

First, it de4nes a service inter*ace to the other o":ects on the same computer that want to use its communicationservices+ This service inter*ace de4nes the operations that local o":ects can per*orm on the protocol+ .econd, aprotocol de4nes a peer inter*ace to its counterpart (peer) on another machine+ This second inter*ace de4nes the

*orm and meaning o* messages echanged "etween protocol peers to implement the communication service+

This would determine the way in which a requestreply protocol on one machine communicates with its peer onanother machine+

OSI R"("r"nc" Mod"l%

To ensure that the nationwide and worldwide data communication systems can "e developed and are compati"le

to each other, an international group o* standard has "een developed+ These standards will *it into a *ramework

which has "een developed "y the International 3rgani6ation o* standardi6ation+ This *ramework is called as

odel *or 3pen system Interconnection (3.I) and known as 3.I re*erence model+


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2unctonalt"s us"d n "ac) OSI ay"r ar" as (ollos%

P)yscal

ay"r

!oncerned with transmitting raw "its over a communication channel, make and "reak

connection, de*ine voltage and data rates, convert digital signal into electric signal+

Data n/ &reaking the data into *rames and transmit them sequentially, .ynchroni6ation, error detection

and correction etc+

N"tor/ Internetworking, Addressing, Routing, 1acketi6ing and Fragmenting+

Trans+ort 1acketi6ing, !onnection !ontrol, Addressing, Accepts data *rom a"ove layers, split into

smaller units and passes to the network layer, and ensure that the pieces all arrive correctly atthe other end, ultipleing etc

A++lcaton Retrans*erring *iles o* In*ormation, Login, 1assword !hecking etc, 0ata"ase Access, 2'mail

and File trans*er+

Protocols us"d n "ac) OSI ay"r ar" as (ollos%

P)yscal ay"r R.?@? or R.B

Data n/ Remote !ontrol, C+?D, 3.1F

N"tor/ I1, I!1, I91, AR1, RAR1, RI1, &91

Trans+ort RT1, T!1, 701

A++lcaton /TT1, FT1, TFT1, T2LN2T, 0/!1, 0N., .N1, NF., NT1

N"tor/n* d"&c"s us"d n "ac) OSI ay"r ar" as (ollos%

P)yscal

ay"r

Repeaters, 1assive and Active /u"s, terminators, Transmitters, receivers, ultipleers etc

Data n/ &ridges, Intelligent /u"s, Network Inter*aces, .witches

N"tor/ Router and 9ateways

Trans+ort '

A++lcaton 9ateways

0i**erence "etween 3.0I and T!1I1 odels are as *ollows-

1rotocols in the 3.I model are hidden and can "e replaced easily as the technology changes, which is one o*the main o":ectives o* layered protocols+

3.I odel is developed "e*ore protocols, hence *unctionalities in each layer are not very optimi6ed+ In

T!1I1, protocols are invented "e*ore odel, hence *unctionalities are per*ectly descri"ed+

In 3.I, there are E layers, while in T!1I1 there are layers+

In 3.I, &oth communications are supported in the network layer, "ut only connection'oriented

communication in the transport layer+ In T!1I1 connectionless mode is supported in network and "oth

modes in transport layer are supported+

1resentation and session layers are not present in T!1I1 model+ .ession layer characteristic are provided "y

the transport layer while 1resentation Layer services are provided "y the application layer+


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0ata 2ncapsulation- ($ith eample)

A packet is "orn, the packet is wrapped in a header "y the *irst protocol (say, the TFT1 protocol), then the

whole thing (TFT1 header included) is encapsulated again "y the net protocol (say, 701), then again "y the

net (I1), then again "y the *inal protocol on the hardware (physical) layer (say, 2thernet)+ $hen anothercomputer receives the packet, the hardware strips the 2thernet header, the kernel strips the I1 and 701 headers,

the TFT1 program strips the TFT1 header, and it *inally has the data+

Networking 1rinciples-

>) Networks provide the in*rastructure to support agency "usiness and administrative processes+

?) Networks must "e operational, relia"le and availa"le *or essential "usiness processes and mission critical"usiness operations+

@) Networks must "e designed *or growth, *lei"ility and adapta"ility+

) Networks must use industry'proven mainstream technologies "ased on industry'wide open standardsand open architecture+

D) Networks must "e designed with con*identiality and security o* data as a high priority+

) Network access must "e a *unction o* authentication and authori6ation and not o* location+

E) Networks must "e designed to support converged services while accommodating traditional data, voiceand video services and should "e application aware in the delivery o* "usiness critical application

systems+

Network .ervices- The various services provided "y the network are - Authentication services, 0irectory, 0/!1(0ynamic /ost !on*iguration 1rotocol), 0N. (0omain Name .erver), ail .ervices, Network *ile .ervices

.haring and remote login etc +

1.3 2utur" n"tor/s 4Int"rn"t 0 ATM 0 Cabl" TV0 Wr"l"ss 5 6lu"toot)0 W'20 W'Ma,0 C"ll +)on"7

$ireless Networks- $ireless technologies di**er in a variety o* dimensions, most nota"ly in &andwidth they

provide, /ow *ar apart communicating nodes can "e, $hich part o* the electromagnetic spectrum they use(including whether it requires a license) and /ow much power they consume (important *or mo"ile nodes)

There are "asically two types-


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>) Fied $ireless systems- There is no mo"ility or less mo"ility+ .imilar to conventional LAN ecept *or the

di**erent that it does not need any ca"ling+?) o"ile wireless systems- .upport mo"ility o* computing devices used to access resource o* wireless

network+ Thus supports high e**iciency, well utili6ation+ 2ample includes smart phones, personal digita

assistants and pagers with Internet access+

0i**erent wireless technologies are- ?9 and @9 technologies, $ireless LAN, $i'a, $ireless Local Loop

($LLs), Radio'Router technology, ultihop $ireless network and $ireless Application protocol

WMA8%

$iAC stands *or worldwide Interopera"ility *or icrowave Access+ It is "ased on I222 GH?+> standard+

0ata communication over long distance in di**erent ways' including 11 link 7se*ul *or providing wireless"road"and access to those area where we do not have a good copper network or ca"le T# network+ Advantages

are Interopera"ility and operate in *requency "and o* @+@ to @+9/6+ $iAC provides up to EH "ps to a

single su"scri"er station+ The physical layer protocols provide two ways to divide the "andwidth "etweenupstream (i+e+, *rom su"scri"ers to "ase station) and downstream tra**ic- time division dupleing (T00) and

*requency division dupleing (F00)+

In order to adapt to di**erent *requency "ands and di**erent conditions, $iAC de4nes several physical layer

protocols+ The original $iAC physical layer protocol is designed to use *requencies in the >H to 9/6range+ In this range waves travel in straight lines, so communication is limited to line'o*'sight (L3.)+ A

$iAC "ase station uses multiple antennas pointed in di**erent directions= the area covered "y one antenna


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Wr"l"ss ocal oo+s 4W7%.upports *ied wireless systems+ 1rovide good "andwidth, used *or high'speed

Internet Access and data trans*er in addition to the "asic telephone service+ It "ypasses wired local loop andthus reduces their access charges+ It is used to provide telephone and low'speed data trans*er service+

Rado Rout"r T"c)nolo*y%It is 2merging wireless technology designed to make links in an I1 network mo"ileIt uses radio transmission *ramework *or packet "ased "road"and I1 wireless communication+ It "uilds up on the

top o* eisting I1 in*rastructure and thus inepensive.

Mult)o+ Wr"l"ss N"tor/s% I* there is no wired in*rastructure, ultihop wireless Network are used+ It isalso known as instant in*rastructure systems which provide wireless communications capa"ility in such

environments+

W'2% It is a mechanism *or wirelessly connecting electronics devices+ A device ena"led with $i'Fi, such as

personal computer, video game console, smartphones, or digital audio player can connect to the Internet via a

wireless network access point+ An access point or hotspot has a range o* a"out ?H meters indoors and a greaterrange outdoors+ ultiple overlapping access points can cover large areas+ There are more than million

hotspots and more than EHH million people using it+ $i'Fi main use is in home networking+ /otspots are also

used in various places such as co**ee shops and small alls too+ It uses spread spectrum technology calledorthogonal *requency division multipleing (3F0) and can achieve speeds o* up to D mega"its per second in

the ?+9/6 "and+

Wr"l"ss AN% A wireless LAN (or $LAN) is one in which a mo"ile user can connect to a local area networkthrough a wireless (radio) connection+ The I222 GH?+>> group o* standards speci*ies the technologies *or

wireless LANs+ 2ach device is equipped with short range transmitter and receiver to allow communication

"etween them+ The wireless LAN is standardi6ed using I222 GH?+>> standard+ Two di**erent modes- In thepresence o* &ase .tation and $ithout &ase .tation (Ad'hoc Networking)+ Architecture o* wireless LAN is as

shown in *igure+

6lu"toot)%.mall >+D inch square radio chip to "e plugged into computers, printers, mo"ile phones, etc+

&luetooth chip is designed to replace ca"les "y taking the in*ormation and transmitting it at a special *requencyto a receiver &luetooth chip, which will then give the in*ormation received to the computer, phone whatever+ It

is an open speci*ication *or short range wireless transmission o* voice and data+ It provides wireless

connectivity "etween phones, laptops and other porta"le handheld devices+ It thus provides Radio link "etween

mo"ile computers, mo"ile phones and other porta"le devices+ It creates 1AN+ (1ersonal Area Network)Transmission o* voice and data takes place over I. *requency "and ?+9/6+ (up to >"ps)+ It uses short


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packets and *ast A!J to increase relia"ility and supports distance up to >Hm+ 0istance could "e etended to

>HHm "y using an ampli*ier+ It also supports encryption and authentication mechanism+

1iconet is the collection o* devices connected in an ad hoc *ashion+ 3ne unit acts as master and the others as

slaves *or the li*etime o* the piconet+ 2ach piconet has one master and up to E simultaneous slave+ asterprovides clock and device I0 to slaves+ @ "it address given to master and G "it address to slaves+ .catternet is

linking o* multiple co'located piconets through the sharing o* common master or slave devices+ 0evices can "e

slave in one piconet and master o* another+ 0evices :umps "ack and *orth "etween the piconets+

$orking- 7ses spread spectrum technology+ Frequency hopping with EB channels using each *or ?Dum at a

time+ .ynchronous Time 0ivision ultipleing is used+ Frame takes up >, @, or D consecutive time slots+ 3nly

the master can start to transmit in odd'num"ered slots+ A slave can start to transmit in an even'num"ered slot"ut only in response to a request *rom the master during the previous slot+

Advantages are low power consumption, Low cost, No license required and 7sed *or > to DHm distance+Applications are Tra**ic control devices, "ar code scanners, edical equipment, 1!s, Laptops, o"iles and

Intelligent /ome appliances etc+ 0isadvantages are speed is limited (> "ps) while wireless networks support

D "ps+ There are used *or short 0istance (Typically DH m) and .ecurity Limitation as it uses speci*icsequence o* channel hopping+

A slave device can "e parked- set to an inactive, low'power state+ A parked device cannot communicate on the

piconet= it can only "e reactivated "y the master+ A piconet can have up to ?DD parked devices in addition to itsactive slave devices+ Kig&ee is a newer technology that competes with &luetooth to some etent+ 0evised "y the

Kig&ee alliance and standardi6ed as I222 GH?+>D+, it is designed *or situations where the "andwidth

requirements are low and power consumption must "e very low to give very long "attery li*e+ It is also intendedto "e simpler and cheaper than &luetooth, making it *inancially *easi"le to incorporate in cheaper devices such

as a wall switch that wirelessly communicates with a ceiling'mounted *an+

Ad'9oc Wr"l"ss N"tor/s%

An ad'hoc wireless network is a collection o* wireless mo"ile hosts *orming a temporary network without the

aid o* any esta"lished in*rastructure or centrali6ed control+ Ad'hoc wireless networks were traditionally o*interest to the military+ Throughout the EHs and GHs 0AR1A *unded much work in the design o* ad'hoc packet

radio networks= however the per*ormance o* these networks was somewhat disappointing+ Ad'hoc wireless

networking is eperiencing a resurgence o* interest due to new applications and improved technology+ These

networks are now "eing considered *or many commercial applications including in'home networking, wirelessLANs, nomadic computing, and short'term networking *or disaster relie*, pu"lic events, and temporary o**ices+

&oth the I222 GH?+>> and wireless LAN standards support ad'hoc wireless networking within a small area, and

wider area networks are currently under development+

Ad'hoc networks require a peer'to'peer architecture, and the topology o* the network depends on the location o*

the di**erent users, which changes over time+ In addition, since the propagation range o* a given mo"ile is

limited, the mo"ile may need to enlist the aid o* other mo"iles in *orwarding a packet to its *inal destination+Thus the end'to'end connection "etween any two mo"ile hosts may consist o* multiple wireless hops+ It is a

signi*icant technical challenge to provide relia"le high'speed end'to'end communications in ad'hoc wireless

networks given their dynamic network topology, decentrali6ed control, and multihop connections+

!urrent research in ad'hoc wireless network design is *ocused on distri"uted routing+ 2very mo"ile host in a

wireless ad'hoc network must operate as a router in order to maintain connectivity in*ormation and *orwardpackets *rom other mo"iles+ Routing protocols designed *or wired networks are not appropriate *or this task

since they either lack the a"ility to quickly re*lect the changing topology, or may require ecessive overhead

1roposed approaches to distri"uted routing that quickly adapt to changing network topology without ecessiveoverhead include dynamic source and associativity "ased routing+ 3ther protocols that address some o* the


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di**iculties in supporting multimedia applications over ad'hoc wireless networks include rate'adaptive

compression, power control, and resource allocation through radio clustering+

C"ll P)on"s% A cell phone is a essentially a "attery powered microprocessor with one or more wireless

transmitters and receivers optimi6ed *or voice communication+ .imple cell phone model provides a key"oard,an L!0 screen and a general purpose computing plat*orm, typically supporting ava? o"ile 2dition (?2) or

+N2T compact A1Is+ ore sophisticated model provides a !amera, D&'?H& o* storage space, *ull color

screen, multiple wireless inter*aces and even a $2RTM keypad+ !ell phones must have a glo"ally unique per'

use, hard'to'*orge identi*ier called the International o"ile .u"scri"er Identi*ier (I.I>)+ I.I are allocated "ycell phone providers and allow them to track and "ill *or usage+ A cell phone provider maintains comprehensive

data"ases, called the /ome Location Register (/LR) that keeps track o* the current location o* each I.I, its

usage and associated su"scri"er in*ormation, such as credit card num"er, or prepaid usage authori6ation+

A cell phone that wants to send or receive I1 packets starts "y requesting a packet data protocol contet *rom

the cell phone provider+ This contet assigns it a packet data protocol, a corresponding I1 address, a quality o*services speci*ication and optionally a 0NA Name+ This protocol allows the cell phone network to associate the

cell phone


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UNIT II

ADVANCED TEC9NOO:IES

Syllabus

#irtual circuits, *ied si6e packets, small si6e packets, integrated service, /istory, !hallenges, AT Network

protocols, I1 over AT, $ireless networks- $ireless communication "asics, architecture, mo"ility

management, wireless network protocols+ Ad'hoc networks &asic concepts, routing= &luetooth (GH?+>D+>), $i'

Fi (GH?+>>), $iAC (GH?+>), and 3ptical Network- links, $0 system, 3ptical LANs, 3ptical paths andnetworks+

!.1 Vrtual Crcuts

A widely used technique *or packet switching, which di**ers signi*icantly *rom the datagram model, uses the

concept o* a virtual circuit (#!)+ This approach, which is also called a connection'oriented model, requires thatwe *irst set up a virtual connection *rom the source host to the destination host "e*ore any data is sent+ To

understand how this works, consider Figure, where host A again wants to send packets to host &+ $e can think

o* this as a two'stage process+

The *irst stage is connection setup+O The second is data trans*er+ $e consider each in turn+ In the connectionsetup phase, it is necessary to esta"lish connection stateO in each o* the switches "etween the source and

destination hosts+ The connection state *or a single connection consists o* an entry in a #! ta"leO in eachswitch through which the connection passes+ 3ne entry in the #! ta"le on a single switch contains a virtual

circuit identifier (#!I) that uniquely identi*ies the connection at this switch and that will "e carried inside the

header o* the packets that "elong to this connection, an incoming inter*ace on which packets *or this #! arriveat the switch, an outgoing inter*ace in which packets *or this #! leave the switch and a potentially di**erent #!I

that will "e used *or outgoing packets+

The semantics o* one such entry is as *ollows- I* a packet arrives on the designated incoming inter*ace and that

packet contains the designated #!I value in its header, then that packet should "e sent out the speci*ied

outgoing inter*ace with the speci*ied outgoing #!I value *irst having "een placed in its header+ Note that thecom"ination o* the #!I o* packets as they are received at the switch and the inter*ace on which they are

received uniquely identi*ies the virtual connection+ There may o* course "e many virtual connections

esta"lished in the switch at one time+ Also, we o"serve that the incoming and outgoing #!I values are generallynot the same+ Thus, the #!I is not a glo"ally signi*icant identi*ier *or the connection= rather, it has signi*icance

only on a given link8that is, it has link local scope+ $henever a new connection is created, we need to assign a

new #!I *or that connection on each link that the connection will traverse+ $e also need to ensure that thechosen #!I on a given link is not currently in use on that link "y some eisting connection+


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There are two "road classes o* approach to esta"lishing connection state+ 3ne is to have a network administrator

con*igure the state, in which case the virtual circuit is permanent+O 3* course, it can also "e deleted "y theadministrator, so a permanent virtual circuit (1#!) might "est "e thought o* as a long'lived or administratively

con*igured #!+ Alternatively, a host can send messages into the network to cause the state to "e esta"lished+

This is re*erred to as signaling, and the resulting virtual circuits are said to "e switched+ The salientcharacteristic o* a switched virtual circuit (.#!) is that a host may set up and delete such a #! dynamically

without the involvement o* a network administrator+

A virtual circuit is one which appears to the user as equivalent to a dedicated point'point service "ut ismaintained "y computers+ It will usually transport data at a guaranteed rate ("its) and with guaranteed

relia"ility and error rate+ Internally in*ormation is carried "y many small packets, each with a short virtual

circuit num"er which identi*ies its virtual circuit over that physical link+ #! changes as the packet is switched"y a switch or router *rom one incoming link to an outgoing link, as per the routing ta"les+ It is the com"ination

o* entries in the routing ta"les o* successive switches which de*ines the end'to'end virtual circuits+ 2nd to 2nd

Routing ta"les are used during call esta"lishment (and are identical to the routing ta"les used all the time *ordatagrams)+ #irtual !ircuit routing ta"les are set up *rom the route discovered "y call esta"lishment+ For each

packet, they map *rom PinputQport, inputQ#! to PoutputQport, outputQ#!+

Vrtual Crcuts Stc)n*% In #! switching eplicit connection setup (and tear'down) phase+ .u"sequence

packets *ollow same circuit+ This is also known as connection'oriented model+ Typically wait *ull RTT *orconnection setup "e*ore sending *irst data packet+ $hile the connection request contains the *ull address *or

destination, each data packet contains only a small identi*ier, making the per'packet header overhead small+ I* aswitch or a link in a connection *ails, the connection is "roken and a new one needs to "e esta"lished+

!onnection setup provides an opportunity to reserve resources+

2ample-

Let >>

.imilarly, suppose #!I o* E is chosen to identi*y this connection on the link *rom switch ? to switch @+ #!I o* is chosen *or the link *rom switch @ to host &+ .witches ? and @ are con*igured with the *ollowing #! ta"le+

Incoming Inter*ace Incoming #! 3utgoing Inter*ace 3utgoing #!

@ >> ? E

Incoming Inter*ace Incoming #! 3utgoing Inter*ace 3utgoing #!


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H E >

For any packet that A wants to send to &, A puts the #!I value D in the header o* the packet and sends it to

switch >+ .witch > receives any such packet on inter*ace ?, and it uses the com"ination o* the inter*ace and the#!I in the packet header to *ind the appropriate #! ta"le entry+ The ta"le entry on switch > tells the switch to

*orward the packet out o* inter*ace > and to put the #!I value >> in the header+

1acket will arrive at switch ? on inter*ace @ "earing #!I >>+ .witch ? looks up inter*ace @ and #!I >> in its #!ta"le and sends the packet on to switch @ a*ter updating the #!I value appropriately+ This process continues

until it arrives at host & with the #!I value o* in the packet+ To host &, this identi*ies the packet as having

come *rom host A+

Data*ra$ Stc)n*%No connection setup phase is present+ 2ach packet *orwarded independently+ It is also

known as connectionless model+ There is no round trip delay waiting *or connection setup= a host can send dataas soon as it is ready+ .ource host has no way o* knowing i* the network is capa"le o* delivering a packet or i*

the destination host is even up+ .ince packets are treated independently, it is possi"le to route around link and

node *ailures+ .ince every packet must carry the *ull address o* the destination, the overhead per packet ishigher than *or the connection'oriented model+

.ynchronous Trans*er ode is used in telephone networks+ Time division multipleed synchronous trans*ermode share a physical link+ .T has two ma:or pro"lems- 7nused time slots get wasted and "andwidth get

wasted+

AT (Asynchronous trans*er mode) is a standard *or cell (small and *ied si6e) relay+ AT networks are

connection'oriented+ AT is high speed trans*er technology *or voice, video and data over pu"lic networksAT uses asynchronous T0 *or multipleing cells *rom di**erent channels+ AT stands *or Asynchronous

Trans*er ode+ It com"ines the *lei"ility o* the Internet and uality'o*'service issues o* the telephonenetwork+ AT networks are "ased on some important concepts- #irtual !ircuits, Fied .i6e packets or cells

.mall packet si6e, .tatistical multipleing and Integrated .ervices+ Asynchronous trans*er mode is as shown in

*igure+


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!.! 2,"d S;" Pac/"ts and S$all Pac/"t s;"

Fied si6e packets are used in AT- .ome advantages are simpler "u**er hardware is required+ 1acket arrival

and departure requires us to manage *ied "u**er si6es+ .impler line scheduling is used as each cell takes aconstant chunk o* "andwidth to transmit+ It is also easier to "uild large parallel packet switches+ &ecause o*

*ied si6e packets there is overhead *or sending small amounts o* data+ 1ackets must "e segmented and

reassem"led hence segmentation and reassem"ly cost involves+ Last un*illed cell a*ter segmentation wastes"andwidth

The smaller the cell, the less an endpoint has to wait to *ill it (packeti6ation delay)+ The smaller the packet, thelarger will "e the header overhead+ .tandards "ody "alanced the two to prescri"e G "ytes S D "yte header D@

"ytes

!.- Int"*rat"d S"r&c"s

The term Integrated .ervicesO (o*ten called Int.erv *or short) re*ers to a "ody o* work that was produced "y

the I2TF around >BBD%>BBE+ The Int.erv working group developed speci4cations o* a num"er o* service

classes designed to meet the needs o* various application types+ It also de4nes how R.#1 could "e used tomake reservations using these service classes+

3ne o* the service classes is designed *or intolerant applications+ These applications require that a packet never

arrive late+ The network should guarantee that the maimum delay that any packet will eperience has somespeci4ed value= the application can then set its play"ack point so that no packet will ever arrive a*ter its

play"ack time+ Assumed that early arrival o* packets can always "e handled "y "u**ering+ This service isre*erred to as the guaranteed service+ In addition to the guaranteed service, the I2TF considered several other

services, "ut eventually settled on one to meet the needs o* tolerant, adaptive applications+ The service is known

as controlled load and was motivated "y the o"servation that eisting applications o* this type run quite well on

networks that are not heavily loaded+ The audio application vat, *or eample, ad:usts its play"ack point asnetwork delay varies, and produces reasona"le audio quality as long as loss rates remain on the order o* >HU or

less+ The aim o* the controlled load service is to emulate a lightly loaded network *or those applications that

request the service, even though the network as a whole may in *act "e heavily loaded+ The trick to this is to usea queuing mechanism such as $F to isolate the controlled load tra**ic *rom the other tra**ic, and some *orm

o* admission control to limit the total amount o* controlled load tra**ic on a link such that the load is keptreasona"ly low+The current *ive classes o* service are-

>+ &est 2**ort ' this is the traditional service model o* the Internet, as descri"ed a"ove, typically

implemented through FIF3 queuing in routers+

?+ Fair ' this is an enhancement o* the traditional model, where there are no etra requests *rom the users"ut the routers attempt to partition up network resources in some *air share sense+ This is typically

implemented using a random drop approach to overload, possi"ly com"ined with some simple round

ro"in serving o* di**erent sources+


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@+ !ontrolled load ' this is an attempt to provide a guarantee that a network appears to the user as i* there is

little other tra**ic ' it makes no other guarantees ' it is really a way o* limiting the tra**ic admitted to thenetwork so that the per*ormance perceived is as i* the network were over'engineered *or those that are

admitted+

+ 1redictive or controlled delay ' this is where the delay distri"ution that a particular *low perceives iscontrolled ' this requires the source (or a group where it is applied collectively to all sources sending to a

group) to make some pre'statement to the routers that a particular throughput is required+ This may "e

re:ected+

D+ 9uaranteed ' this is where the delay perceived "y a particular source or to a group is "ounded withinsome a"solute limit+ This may entail "oth an admission test as with @, and a more epensive *orwarding

queuing system+

!.3 ATM0 ATM ay"rs0 IP O&"r ATM

AT network is made up o* an AT switch and AT endpoints+ AT switch is responsi"le *or cell transit

through an AT network+ AT endpoint contains an AT network inter*ace adapter+ 2amples areworkstations, routers, LAN switches etc+

AT switches support two primary types o* inter*aces- 7NI (7nser'Network Inter*ace) and NNI (Network'

Network Inter*ace)+ The 7NI connects AT end systems to an AT switch+ The NNI connects two AT

switches+ It could also "e *urther divided into private and pu"lic 7NI or NNI+

AT cell is D@ "ytes long+ G "ytes data and D "ytes are allocated *or header+ AT cell header can "e one o*

two *ormats- 7NI or NNI+ 7NI header is used *or communication "etween AT end points and AT switches

NNI header is used *or communication "etween AT switches+

2*ur"% ATM C"ll 43< byt"s data and = byt"s )"ad"r7

AT networks are *undamentally connection'oriented+ /ence #! must "e set up across AT network "e*ore

data trans*er+ Two types o* AT connections eist- #irtual 1ath identi*ied "y #1I and #irtual channel identi*ied

"y the com"ination o* a #1I and #!I+ #1 is a "undle o* #!, all o* which are switched transparently across the

AT network "ased on the common #1I+


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2*ur"% Vrtual Pat) and Vrtual Crcuts

2*ur"% ATM N"tor/s

ATM ay"rs

2*ur"% ATM ay"rs

AAL protocols accept transmission *rom upper'layer services (e+g+, packet data) and map them into *ied'si6ed

AT cells+ 0ata types supported are !onstant'"it'rate (!&R) data, #aria"le'"it'rate (#&R) data, !onnection'

oriented packet data and !onnectionless packet data+

AAL> % !&R data- video, voice etc, Application require guaranteed "it rate

AAL? % #&R data

AAL@ % !onnection'oriented data

AAL % !onnectionless data


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AALD % 1oint'to'point transmission without processing+

ATM ay"r%

AT Layer contains various *ields such as #1I (#irtual 1ath Identi*ier), #!I (#irtual !ircuit Identi*ier)

9F!- 9eneric Flow !ontrol means to ar"itrate access to a link on a shared medium+!L1- !ell Loss 1riority which indicates that packet may "e dropped+ A cell dropped may not cause signi*icant

change in video data+/2!- /eader 2rror !ontrol which indicates header checksum+

The AAL layer used "y the I1 protocol is AALD+ 3nly the last cell carries the G'"yte trailer added to the I1

datagram+ 1adding can "e added only to the last cell or the last two cells+ The value o* the 1T *ield is HHH in allcells carrying an I1 datagram *ragment ecept *or the last cell= the value is HH> in the last cell+

2*ur"% IP O&"r ATM 42ra*$"ntaton7

IP O&"r ATM

I1 over AT is a group o* components that do not necessarily reside in one place and in this case, the services

are not usually on an AT switch+ In some cases, switch vendors provide some I1 over AT support, "ut notalways+ I1 over AT approach provides several attractive advantages over 2LAN solutions+ The most o"vious

advantage are its a"ility to support o. inter*aces, its lower overhead (as it don


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2*ur"% ATMARP 9"ad"r 2or$at

The operation *ield can take the values > *or request, ? *or reply, G *or inverse request, B *or inverse reply and >H*or NA!J+ The inverse request and inverse reply messages can "ind the physical address to an I1 address in a

1#! situation+ The request and reply message can "e used to "ind a physical address to an I1 address in an .#!situation+ The inverse request and inverse reply can also "e used to "uild the server


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o*cal IP Subn"t 4IS7%An AT network can "e divided into logical (not physical) su"'networks+ This

*acilitates the operation o* ATAR1 and other protocols (such as I91) that need to simulate "roadcasting onan AT network+ LI. allows an AT network to "e divided into several logical su"nets+ To use ATAR1, we

need a separate server *or each su"net+

2*ur"% IS

!.= Wr"l"ss N"tor/s% Wr"l"ss Co$$uncaton 6ascs0 Arc)t"ctur"0 $oblty Mana*"$"nt0 Wr"l"ss

N"tor/ Protocols

$ireless is a term used to descri"e telecommunications in which electromagnetic waves carry the signal+ A

wireless network is de*ined as technology that allows two or more computers, to communicate, using standardprotocol "ut without the use o* network ca"ling+ A wireless LAN (or $LAN) is one in which a mo"ile user can

connect to a local area network through a wireless (radio) connection+ The I222 GH?+>> group o* standards

speci*ies the technologies *or wireless LANs+Advantages o* wireless networks are-

>+ o"ility improves productivity and service+

?+ 1orta"le and *lei"le+@+ 2asy to install+

+ .cala"ility ' 2asy to recon*igure+D+ /igh speed and simplicity++ Reduced overall cost

E+ akes availa"le real'time data in "roader range o* coverage areas

$orking- 2ach device is equipped with short range transmitter and receiver to allow communication "etween

them+ Two di**erent modes are used in the presence o* &ase .tation and without &ase .tation (Ad'hocNetworking)

$LAN consist o* two main components- an Access 1oint and wireless adapters+ A "ridge and an antenna canalso "e used+ An access point looks like an eternal modem with two small antennae+ Radio cards are also

called $LAN cards+ The range o* an GH?+>>" $LAN is typically >HH *eet and can "e etended to several

hundred *eet "y using an antenna+ $ireless "ridges are similar to the wired "ridges and are used to connect two$LANs+


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2*ur"% Arc)t"ctur" o( r"l"ss N"tor/s

A1 (Access 1oint)&.. (&asic .ervice .et)

2.. (2tended .ervice .et)

Three transitions take place "etween mo"ile hosts in wireless networks+ No transition which indicates stationary

or mo"ile hosts moves only within &..+ In &.. transition, .tations moves *rom one &.. to another &.. in

same 2.. while in 2.. transition, .tation moving *rom &.. in one 2.. to &.. within another 2..

The various kinds o* services provided are as *ollows-

Dstrbuton syst"$s S"r&c"s 4DSS7

Association- oving station associates with access point+

Re'association- oving station when enters in range o* another A1, he associates with new access point+

0is'association- $hen moving *rom one &.. to another &.., old association "etween mo"ile host and old

A1 get lost+ 0istri"ution- 0ata trans*er *rom one mo"ile host to another within single 2..+

Integration- Integration o* wireless technology with wired network+

Staton S"r&c"s 4SS7. The various services provided are Authentication (3pen system or .hared Jey)+ 0e'

authentication, 1rivacy and 0ata delivery

The various managements *rames used are-

Authentication Frame

0e'authentication Frame

Association request and response *rame

Re'association request and response *rame

0is'association *rame

&eacon *rame

1ro"e request *rame+

&eacon management *rame- A1 periodically sends it to announce its presence and relay in*ormation+ .tations

can select A1 as per their choice+

1ro"e request management *rame- .tation will respond with a pro"e request *rame a*ter receiving "eacon *rame+

9dd"n Nod" Probl"$%


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A is sending a message to &, "ut ! is out o* its range and hence while VlisteningV on the network ! will *ind the

network to "e *ree and might try to send packets to & at the same time as A+ There will "e a collision at &+ Thepro"lem can "e looked upon as i* A and ! are hidden *rom each other+ /ence it is called the Vhidden node

pro"lemV+

E,+os"d Nod" Probl"$%

I* ! is transmitting a message to 0 and & wants to transmit a message to A, & will *ind the network to "e "usyas & hears ! transmitting+ 2ven i* & would have transmitted to A, it would not have "een a pro"lem at A or 0

!.A!0 would not allow it to transmit message to A, while the two transmissions could have gone in

parallel+

!.A!A 1rotocol- $ireless LAN adaptors cannot detect collisions+ !arrier .ensing % Listen to the media to

see i* it is *ree+ !ollision Avoidance % inimi6e chances o* collision "y starting a random "ack o** timer, when

medium is *ree and prior to transmission

0i**erence "etween wireless and wired LAN are

Wr"d AN Wr"l"ss AN

>+ 2thernet No $ire is used+?+ I222 GH?+@ I222 GH?+>>

@+ !.A!0 !.A!A+ 7T1!oaial !a"le Radio *requency

D+ 2lectrical .ignal Radio ways

+ /igh 2**iciency Low

E+ Large range .hortG+ Addressing is simple !omplicated

IEEE !.11 Arc)t"ctur"%


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2*ur"% IEEE !.11 Arc)t"ctur"

2unctons o( +)yscal lay"r%Functions includes encodingdecoding o* signals, 1ream"le generationremoval

(*or synchroni6ation), &it transmissionreception and also includes speci*ication o* the transmission medium+ It

also provides speci*ication *or converting "its to a RF signal- F/.. (Frequency /opping .pread .pectrum),

0... (0irect .equence .pread .pectrum), 3F0 (3rthogonal Frequency 0ivision), /R'0..(/igh Rate'0...) and 3F0 (GH?+>> g)

>+ F/..- Frequency "and is ?+ 9/6 I. &and (?+H? % ?+GH 9/6)+ The "and divided into EB equal su""ands o* > /6 each+ .ender sends one *requency *or a short period o* time, then hope to another carrier

*requency+ Thus there are N such hopping in one cycle+ The cycle repeats itsel* a*ter N hopping+ ain

advantage is that unauthori6ed person cannot understand transmitted data+?+ 0...- Frequency "and is ?+ 9/6 I. &and+ 2ach "it is *irst converted into a group o* "its called as chip

code+ For eample *or H, chip code is >HHH>>, *or > chip code is >>>H>H etc+

@+ /R 0...- Frequency "and is ?+ 9/6 I. &and+ 2ncoding is also used+ or G "its o* original dataconverted into one sym"ol+

+ 3F0- Frequency "and is D 9/6 I. &and+ &and is su" divided into D? su" "ands+ G are used *orsending G groups o* "its and are used *or sending control in*ormation+ These su" "ands are used

randomly in order to increase the security o* transmitted data+

2unctons o( $"du$ acc"ss control 4MAC7 lay"rincludes- 3n transmission, assem"le data into a *rame with

address and error detection *ields, on reception, disassem"le *rame and per*orm addressrecognition and error detection+ Logical link control (LL!) Layer provides an inter*ace to higher layers and

per*orm *low and error control+

Wr"l"ss N"tor/ Protocol

The $A1 architecture provides a scala"le and etensi"le environment *or application development *or mo"ile

communication devices+ This is achieved through a layered design o* the entire protocol stack as shown in thediagram+ 2ach o* the layers o* the architecture is accessi"le "y the layers a"ove as well as "y other services andapplications+ The $A1 layered architecture ena"les other services and applications to utili6e the *eatures o* the

$A1 stack through a set o* well de*ined inter*aces+ 2ternal applications may access the session, transaction,

security and transport layers directly+

Layer $ireless Application 2nvironment ($A2)

Layer D $ireless .ession 1rotocol ($.1)

Layer $ireless Transaction 1rotocol ($T1)

Layer @ $ireless Transport Layer .ecurity ($TL.)

Layer ? $ireless 0atagram 1rotocol ($01)


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Layer > &earer Layer (9., !0A, 91R. etc+)

1. Wr"l"ss A++lcaton En&ron$"nt 4WAE7

The $A2 provides a general purpose application environment "ased on a com"ination o* $$$ and o"ile

Telephony technologies+ The primary o":ectives is to esta"lish an interopera"le environment that will allow

operators and service providers to "uild applications and services that can reach a wide variety o* di**erentwireless plat*orms containing the various *unctionalities such as $ireless arkup language($L), $L

.cript, $ireless Telephony Application etc+

!. Wr"l"ss S"sson Protocol 4WSP7

The $.1 provides the application layer o* $A1 with a consistent inter*ace *or two session services+ The *irst is

a connection oriented service that operates a"ove the transaction layer protocol $T1+ The second is a

connectionless service that operates a"ove a secure or non secure datagram service ($01)+

-. Wr"l"ss Transacton Protocol 4WTP7

The $T1 runs on a top o* a datagram service and provides as a light weight transaction oriented protocol that issuita"le *or implementation in thin clients (mo"ile stations)+ $T1 operates e**iciently over secure or non secure

wireless datagram networks and provides various services such as relia"le one way request, relia"le two way

request'reply transactions etc+

3. Wr"l"ss Trans+ort ay"r S"curty 4WTS7

$TL. is a security protocol "ased on the industry standard Transport Layer .ecurity (TL.) protocol *ormerly

known as .ecure .ockets Layer (..L)+ $TL. is intended *or use with the $A1 transport protocols and has"een optimi6ed *or use over narrow'"and communication channels+ It also provides various *eatures such as

0ata integrity, privacy, Authentication and 0enial o* service 1rotection+

=. Wr"l"ss Data*ra$ Protocol 4WDP7

The transport layer protocol in the $A1 architecture is re*erred to as 201+ The 201 layer operates a"ove the

data capa"le "earer services supported "y the various network types+ As a general transport service, $01 o**ersa consistent service to the upper layer protocols o* $A1 and communicates transparently over one o* the other

availa"le "earer services+

Internet can "e accessed on mo"ile phones+ A mo"ile phone will have a "uilt in screen *or wireless access to e'mail and the+ .uch as system is called $A1O A $A1 device can "e a mo"ile phone or Note"ook computer+ The

users can call a $A1 gateway over the wireless link and send we" pages requests to it+ The gateway then checks

its cache *or the requested page+ I* present, it sends it else it *etches it over the wired internet+ $A1 has twoversions- $A1>+H and $A1?+H+ The $A1>+H is a circuit switched system "ut it has a very high per minute

connect charge+ &ut $A1?+H and I'mode "ecomes success*ul+ $A1?+H uses packet switching in place o* circuit

switching+ It is designed to support a large num"er o* devices+ It has pull (data comes a*ter requesting it) andpush model (data comes without requesting it) and supports multimedia messaging+

!.? Ad')oc n"tor/s 6asc conc"+ts0 routn*(Re*er 7NIT *or detail)

!.@ 6lu"toot) 4!.1=.170 W'2 4!.1170 WMA8 4!.1?7

(Re*er 7NIT > *or detail)

?+G O+tcal N"tor/% ln/s0 WDM syst"$0 O+tcal ANs0 O+tcal +at)s and n"tor/s.

3ur current age o* technologyO is the result o* many "rilliant inventions and discoveries, "ut it is our a"ility totransmit in*ormation, and the media we use to do it, that is perhaps most responsi"le *or its evolution

1rogressing *rom the copper wire o* a century ago to today


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development in all areas+ Today@>H or >DDH nanometers+

T)" 2b"r O+tc Cabl"% The ca"le consists o* one or more glass *i"ers, which act as waveguides *or the opticalsignal (light)+ Fi"er optic ca"le is similar to electrical ca"le in its construction, "ut provides special protection*or the optical *i"er within+ For systems requiring transmission over distances o* many kilometers, or where two

or more *i"er optic ca"les must "e :oined together, an optical splice is commonly used+

T)" O+tcal R"c"&"r% The receiver converts the optical signal "ack into a replica o* the original electrical

signal+ The detector o* the optical signal is either a 1IN'type photodiode or avalanche'type photodiode+

3ptical *i"er uses carrier *requency o* the order o* >H>D /6+ &andwidth generally a smaller *raction o* carrier

*requency+ Large &$ is availa"le (o* the order o* H T/6)+ 3ptical *i"er has low loss in >+@ mm and >+DD mm"ands+

Ad&anta*"s o( (b"r% Fi"er optic transmission systems % a *i"er optic transmitter and receiver, connected "y*i"er optic ca"le % o**er a wide range o* "ene*its not o**ered "y traditional copper wire or coaial ca"le+ These

include-

' The a"ility to carry much more in*ormation and deliver it with greater *idelity than either twisted pair wire

or coaial ca"le+' Fi"er optic ca"le can support much higher data rates, and at greater distances, than coaial ca"le, making it

ideal *or transmission o* serial digital data+

' The *i"er is totally immune to virtually all kinds o* inter*erence, including lightning, and will not conductelectricity+ It can there*ore come in direct contact with high voltage electrical equipment and power lines+ It

will also not create ground loops o* any kind+

' As the "asic *i"er is made o* glass, it will not corrode and is una**ected "y most chemicals+ It can "e "urieddirectly in most kinds o* soil or eposed to most corrosive atmospheres in chemical plants without

signi*icant concern+

' .ince the only signal in the *i"er is light, there is no possi"ility o* a spark *rom a "roken *i"er+ 2ven in the

most eplosive o* atmospheres, there is no *ire ha6ard, and no danger o* electrical shock to personnelrepairing "roken *i"ers+

' A *i"er optic ca"le, even one that contains many *i"ers, is usually much smaller and lighter in weight than a

wire or coaial ca"le with similar in*ormation carrying capacity+ It is easier to handle and install, and usesless duct space+ (It can *requently "e installed without ducts+)

' Fi"er optic ca"le is ideal *or secure communications systems "ecause it is very di**icult to tap "ut very easy

to monitor+ In addition, there is a"solutely no electrical radiation *rom a *i"er+

0ue to all these advantages- 3ptical *i"er Networks have high capacity+ They can "e used *or providing the

high "andwidth services+ 2ven in wireless, in*rared means high "andwidth connectivity+ All the networks usingoptical *i"er as transmission medium are called as optical networks+ $hen transmitted signal remains in optical

*orm till its arrival at destination are all optical network+ 0egradation o* signal in optical *i"er called as

0ispersion and Attenuation+ All'optical networks are "roadcast networks ' transmitted optical signal ' received

"y everyone+ They are also .witched ' transmitted optical signal ' switched through a speci*ic path and received"y the designated receiver+

O+tc Trans$tt"rs% The "asic optical transmitter converts electrical input signals into modulated light *ortransmission over an optical *i"er+ 0epending on the nature o* this signal, the resulting modulated light may "e


25/64

turned on and o** or may "e linearly varied in intensity "etween two predetermined levels+ The most common

devices used as the light source in optical transmitters are the light emitting diode (L20), the vertical cavityside emitting laser (#!.2L) and the laser diode (L0)+ In a *i"er optic system, these devices are mounted in a

package that ena"les an optical *i"er to "e placed in very close proimity to the light emitting region in order to

couple as much light as possi"le into the *i"er+

O+tcal R"c"&"rs% The "asic optical receiver converts the modulated light coming *rom the optical *i"er "ack

into a replica o* the original signal applied to the transmitter+ The detector o* this modulated light is usually a

photodiode o* either the 1IN or the Avalanche type+ This detector is mounted in a connector similar to the oneused *or the L20, #!.2L or L0+ 1hotodiodes usually have a large sensitive detecting area that can "e several

hundred microns in diameter+ This relaes the need *or special precautions in centering the *i"er in the receiving

connector and makes the alignmentO concern much less critical than it is in optical transmitters+

WDM%$0 is a F0 (Frequency 0ivision ultipleing) technique *or *i"er optic ca"le in which multiple

optical signal channels are carried across a single strand o* *i"er at di**erent wavelengths o* light+ Thesechannels are also called lam"da circuits+ 2ach wavelength is o* di**erent color o* light in the in*rared range that

can carry data+ $ith the eponential growth in communication, caused mainly "y the wide acceptance o* the

Internet, many carriers are *inding that their estimates o* *i"er needs have "een highly underestimated+ &ecause$0 allows the large "andwidth o* the optical *i"er to "e more *ully utili6ed, optical *i"er "ecomes more than

a simple >-> replacement *or copper wires (one channel per *i"er)+ 3ptical multipleing ena"les an N->capa"ility (N channels per *i"er, where each channel may operate at the *ull electronics limit, allowing multi'

giga"it per second aggregate data rates)+

SONET 4Sync)ronous O+tcal n"tor/7- .3N2T is "asically a $AN which is used as a transport network to

carry voicevideodata tra**ic *rom one $AN to other $AN+ 3ptical network supports high data ratetechnologies as well as low data rate technologies+ AN.I developed .3N2T which is a synchronous network

using synchronous T0 technique+ In this all clocks applied in the system are locked to a master clock+

0i**erent "asic .3N2T devices used are .T. ultipleer0e'multipleer, regenerator, Add0rop multipleerand terminals+ .tart and 2nd points o* a .3N2T link are marked "y this unit+ It is inter*ace "etween electrical

network and optical network+ .T. 7C has electrical input and optical output, whereas .T. 0emu has

optical input and electrical output+ Regenerator is "asically a repeater which per*orms the various *unctionssuch as regenerating signals and replacing some o* the eisting overhead (!ontrol in*ormation) with new

in*ormation+ Insertion Identi*ication Reorgani6ation and 2traction o* incoming optical data stream are

per*ormed "y A000R31 multipleer+


26/64

UNIT III

PER2ORMANCE O2 NETWORKS

Syllabus

!ontrol o* networks- 3":ectives and methods o* control, !ircuit .witched networks, 0atagram and ATnetworks, athematical "ackground *or control o* networks like !ircuits .witched networks, 0atagram and

AT networks+

-.1 Control o( N"tor/s% Ob"ct&"s and $"t)ods o( Control!all Admission !ontrol is a key element in the provision o* guaranteed quality o* service in circuit switched

network+ !all Admission !ontrol is a technique to provide o. in a network "y restricting the access to

network resources+ .imply rated, an admission control mechanism accepts a new call request provided there areadequate *ree resources to meet the o. requirement o* the new call request without violating the committed

o. o* already accepted calls+ $ith the constant increase in the num"er o* voice over packet network users,

uality o* service "ecomes crucial *or the success o* this type o* real time applications+ 3ne o* the uality o*service techniques plays an important role- a decision process that takes place in voice gateways and is

responsi"le *or allowing calls only when the epected level o* per*ormance in the network can "e assured

Admission control determines which circuits switched connections are accepted or not in the network+

A call that requires a guaranteed service is su":ect to call admission control to determine i* the network hassu**icient resources to *ul*ill its contractual o"ligations+ 3nce admitted, policing control ensures that the call

does not violate its part o* the contract+ 1olicing controls are applied on the timescale o* call inter'arrival times+!A! is applied on the timescale o* call inter'arrival times+ .ince call inter'arrival times can "e relatively short,

admission decisions must usually "e "ased upon in*ormation that is availa"le at the entry node+ Thus

in*ormation must control the admission policy and re*lect the a"ility o* the network to carry calls o* given typesto particular destinations+ It is not realistic to have complete in*ormation a"out the state o* the network at the

time o* each admission decision+ This would require ecessive communication within the network and would "e

impossi"le *or networks whose geographic span means there are large propagation delays+ A common approachis *or the network management to keep this in*ormation as accurate as possi"le and update it at time intervals o*

appropriate length+ !learly, more accurate !A! allows *or "etter loading o* the links= less "locking o* calls, and

ultimately more pro*it *or the network operator+ To assess the capacity o* the network as a transport serviceproduction *acility, we need to know its topology, link capacities and call admission control policy+ Together

these constraint the set o* possi"le services that the network can support simultaneously+

Ob"ct&"s%$hile the data transmission over the network the o":ective o* protocols to per*orm the *ollowing*unctions *or the error *ree and relia"le transmission o* data+

>+ Data S"#u"ncn*%A long message to "e transmitted is "roken into smaller packets o* *ied si6e *or

error *ree data transmission+?+ Data Routn*%It is the process o* *inding the most e**icient route "etween source and destination "e*ore

sending the data+

@+ 2lo Control% All machines are not equally e**icient in terms o* speed+ /ence the *low control regulates

the process o* sending data "etween *ast sender and slow receiver++ Error Control%2rror 0etecting and recovering is the one o* the main *unctions o* communication

so*tware+ It ensures that data are transmitted without any error+

-.! Control o( N"tor/s% Crcuts Stc)"d N"tor/s

!ircuits switching is a methodology o* implementing a telecommunication network in which two network

nodes esta"lish a dedicated communication channel (circuit) through the network "e*ore the nodes maycommunicate+ The circuit guarantees the *ull "andwidth o* the channel and remains connected *or the duration

o* the telecommunication session+ The circuits *unctions as i* the nodes were physically connected as in an

electrical circuit+ !ircuit switching contrasts with packet switching which divides the data to "e transmitted into


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packets transmitted through the network independently+ 1acket switching shares the availa"le network

"andwidth "etween multiple communication sessions+

In !ircuits switching, the "it delay is constant during a connection, as opposed to packet switching, where

packet queues may cause varying packet trans*er delay+ 2ach circuit cannot "e used "y other callers until thecircuit is related and a new connection is set up+ 2ven i* no actual communication is taking place, the channe

remains unavaila"le to other users+ !hannels that are availa"le *or new calls are said to "e idle+ #irtual circuits

switching is a packet switching technology that emulates circuits switching, in the sense that the connection is

esta"lished "e*ore any packets are trans*erred and packets are delivered in order+ $hile circuits switching iscommonly used *or connecting voice circuits, the concept o* a dedicated path persisting "etween two

communicating parties or nodes can "e etended to signal content other than voice+ Its advantage s that it

provides continuous trans*er without the overhead associated with packets making maimal use o* availa"le"andwidth *or that communication+ The disadvantage is in*lei"ility= the connection and the "andwidth

associated with it are reserved and unavaila"le *or other use+

For call setup and control, it is possi"le to use a separate dedicated signaling channel *orm the end node to the

network+ I.0N is one such service that uses a separate signaling channel while plain old telephone (13T.) does

not+ The method o* esta"lishing the connection and monitoring its progress and termination through the networkmay also utili6e a separate control channel as in the case o* links "etween telephone echanges which use !!.E

packet switched signaling protocol to communicate the calls setup and control in*ormation and use T0 totransport the actual circuit


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I1 network protocol+ Applications which do not require more than a "est e**ort service can "e supported "y

direct use o* packets in a datagram network, using 701 transport layer protocol+ Application like voice andvideo communications and noti*ying messages to alert a use that shehe has received new email are using 701

Applications like e'mail, $e" "rowsing and *ile upload and download need relia"le communications, such as

guaranteed delivery, error control and sequence control+ This relia"ility ensures that all data received is incorrect order and without errors+ It is provided "y a protocol such as T!1 Transport Layer 1rotocol+

Control o( N"tor/% Data*ra$ N"tor/s

$hen two or more nodes would simultaneously try to transmit packets to one node, there is a high pro"a"ilitythat the num"er o* packets would eceed the packet handling !apacity o* the network and lead to congestion

!ongestion control is a process o* maintaining the num"er o* packets in a network "elow a certain level at

which per*ormance *alls o**

Caus"s o( Con*"ston

Finite queue Length+

.low processor speed+

Limited "andwidth+

Limitation o* Link capa"ility+

Non'uni*ormity o* arrival o* packets+

M"t)ods o( Con*"ston control and 2lo Control

O+"n oo+%Attempt to solve the pro"lem "y good design "ut does not works at run time+ The open loop

*low control mechanism is characteri6ed "y having no *eed"ack "etween the receiver and the sender+ Theallocation o* resources must "e a prior reservation or hop "y hop type+ The open loop *low control has

inherent pro"lems with maimi6ing the utili6ation o* network resources+ Resource allocation is made at

connection setup using a !A! and this allocation is made using in*ormation that is already old news duringthe li*etime o* the connection+ 3*ten there is an over allocation o* resources and reserved "ut unused

capacities are wasted+ 3pen loop *low control is used "y AT+

Clos"d oo+%&ased on the principle o* *eed"ack loop+ onitor the system to detect when and where the

congestion occurs= ad:ust the system operation to correct the pro"lem+ The closed loop *low controlmechanism is characteri6ed "y the a"ility o* the network to report pending network congestion "ack to the

transmitter+ This in*ormation is then used "y the transmitted in various ways to adapt its activity to eisting

network conditions+

Con*"ston control $"t)ods

$arning &it- A special "it in the packet header is set "y the router to warn the source when the congestion is

detected+ This "it is send to the sender in the A!J+ The sender monitors the num"er o* A!J packets itreceives with the warning "it set and ad:ust its transmission rate accordingly+

!hoke packets- $hen congestion occurs, line enters in an alarming situation+ 2ach newly packet is checked

to see i* its output line is in alarming state+ I* so, the router sends the choke packet "ack to the source which

contains destination address, so the source will not generate any more packets along the path+

Con*"ston Control% T!1 sender maintains two windows- the receiver window and the congestion windowAmount o* data, sender may transmit IN (congestion window, receiver window)+ T!1 sender detects

congestion "y monitoring timeouts and increase congestion window until timeout+ 3n timeout, decrease

congestion window+ It includes two phases- slow start and congestion avoidance+

Initially congestion window is o* one maimum segment si6e, increase "y one segment *or each A!J received+

!ongestion window grows eponentially until the threshold is reached+ !ongestion window increased linearly


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when a"ove the threshold+ $hen timeout occurs ' Threshold set to hal* o* the current congestion window

!ongestion window reset to one segment and then run slow start until the threshold is hit+

2lo control and bu(("rn*

There must "e "alance "etween production and consumption rates+ I* the production is *aster than consumptionthen packets get discarded+ I* the consumption is *aster than production, then system "ecomes in'e**icient+

For *low control, a sldn* ndois needed on each connection to keep a *ast transmitter *rom overrunning a

slow receiver+ .ince a host may have numerous () connections, it is impractical to implement the same datalink "u**ering technique (using dedicated "u**ers *or each line)+ The sender should always "u**er outgoing

T107 "yte at a time+ .ending

small amounts o* data are echanged across the network is very ine**icient use o* the network resources+ Thesender can transmit small amounts o* data+ The receiver can advertise small windows+ .ome algorithms are used

to solve the pro"lem- NagleXs algorithm (*or the sender) and !larkXs algorithm (*or the receiver)


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Na*l"Bs and Clar/Bs Al*ort)$% $hen data come into the sender one "yte at a time, :ust send the *irst "yte and

"u**er all the rest until the outstanding "yte is A!Jed+ Then send all the "u**ered characters in one T!1segment and start "u**ering again until the segment is A!Jed+ .ender can also send a segment i* "u**ered data

have *illed hal* o* the window or a maimum segment+ In !lark


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AT switch and glo"al congestion control that regulates cell *low *rom source end systems (terminals) into the

network+

Int"rnal Con*"ston control o( t)" Stc)% It resolves congestion that occurs at a switch in a short time

interval+ For eample, i* multiple cells destined *or the same output link arrive at a switch simultaneously, theoutput link is temporally congested+ In this case, cells should "e queued at the switch "u**er to avoid cell loss+

/owever, the "u**er capacity is actually limited so that some mechanism is needed to reduce the opportunity o*

"u**er over*low+

As an internal congestion control scheme, several types o* AT switch architectures have "een proposed

including output "u**er switch, input "u**er switch, shared "u**er switch, "atcher "anyan switch+ These switches

have tradeo**s "etween per*ormance and implementation compleity+ For eample, output "u**er switch shows"etter per*ormance than other switches (high throughput and low cell loss pro"a"ility) i* all switches have a

*ied amount o* "u**er memory, it cannot "e provided with a large amount o* memory due to cost or technology

limitation+ As a cost e**ective AT switch, another switch architecture that possesses "u**ers on "oth sides o*input and output ports with a "ack pressure *unction+ The key idea o* this switch architecture is to provide a

large amount o* slow speed memory at input ports and a small amount o* *ast speed memory at output ports, and

to increase its per*ormance "y controlling "oth input and output "u**ers with the "ack pressure mechanism+

The "ack pressure *unction is provided to avoid a temporary congestion in the switch "y prohi"iting celltransmission *rom an input "u**er to the congested output "u**er when the num"er o* cells in the output "u**er

eceeds some threshold value+ The num"er o* input ports and output ports is represented "y N+ This switch isequipped with "u**ers at "oth sides o* the input and output ports+ The switching speed o* a cell *rom input "u**er

to output "u**er is N times *aster than the link speed= that is, in a time slot, at most one cell at the input "u**er is

trans*erred to the output "u**er while the output "u**er can simultaneously receive N cells *rom di**erent input"u**ers+ The "ack pressure *unction prohi"its transmission o* cells *rom input "u**er to output "u**er "y

signaling "ack *rom output "u**er to input "u**er when the num"er o* cells in output "u**er eceeds a threshold

value+ &y this control, a cell over*low at the output "u**er can "e avoided+ /owever, it introduces /ead o* Line(/3L) "locking o* cells at the input "u**er, which results in limitation o* the switch per*ormance+

:lobal Con*"ston Control% 3n the other hand, 9lo"al congestion control tries to resolve network widecongestion+ !losed loop rate control is a promising glo"al= congestion control mechanism *or data

communication and is "eing applied to the A&R (Availa"le &it Rate) service class in the AT *orum+ !losed

loop control is also called as reactive congestion control, and it dynamically regulates cell emission process o*

each source end system "y using *eed"ack in*ormation *rom the network+ It is there*ore, especially suita"le *or"est e**ort tra**ic+ For implementation o* closed loop control, two kinds o* schemes were proposed in the AT

*orum- rate "ased and credit "ased+ The credit "ased scheme is "ased on a link "y link window *low control

mechanism+ Independent *low controls are per*ormed on each link *or di**erent connections, and eachconnection must o"tain "u**er reservations *or its cell transmission on each link+ This reservation is given in the

*orm o* a credit "alance+ A connection is allowed to continue cell transmission as long as it gains credit *rom the

net node+ $hen the connection is starved o* credit, it should wait *or credit+ 3wing to this link "y link *ast

*eed"ack mechanism, transient congestion can "e relieved e**ectively+

In addition, no cell loss occurs "ecause no connection can send cells unless it has credit+ The rate "ased scheme,

on the other hand, controls the cell emission rate o* each connection "etween end systems+ It is simpler thancredit "ased *low control schemes in which each switch requires complicated queue management *or every

connection+ Typical eamples o* rate "ased approach are *orward eplicit congestion noti*ication (F2!N) and

"ackward eplicit congestion noti*ication (&2!N), which are well known congestion control strategies inconventional packet switching networks+ Rate "ased congestion control algorithms have "een adopted as the

standard mechanism *or A&R service class+

-.= Mat)"$atcal bac/*round (or control o( n"tor/s


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S"r&c" 4TS7 and Watn* T$" 4TW7% .ervice Time is the time required *or transmission o* message,processing "y the computer, printing and all activities "y the user+ $aiting Time (ueuing delays) is the Time

spends waiting *or the transmission lines and the computer+

Tw Y Ts

T Ts S Tw

!onsider a simple eample- one message service time *or a server (or channel) is >Hms+ It means net message

has to wait *or >Hms+ A*ter then that message get serviced *or >Hms+ Net message in a queue has to wait *or

?Hms and so on+ I* there are only two messages in a queue, then average waiting time is >Dms+ I* the servicetime is more, waiting time is more+ It means i* the num"er o* messages in *ront o* a given message is held

constant, then the waiting time grows proportionally with the service time+ Thus Tw Ts where is thenum"er o* messages in the queue+ &ut also the service time is not *ied= it depends upon the length o* the

message+

Analyss o( D"lay n n"tor/s% $hen the message arrives, it goes into the "u**er o* the server (or channel)+ I*the server is *ree, then the message is processed "y the server+ Thus the delay *or the current message is H+ I* the

server is "usy in processing previous message, the current messages and net messages stored in the "u**er will

get delayed+ $e need to calculate % Average delay and $orst case delay etc+ 0elay occurs "ecause- essagesare more and resources are less+ .erver or channel capacity is limited and inadequate o* service *acilities+

I$+ortant T"r$s us"d ar"%

>+ Arrival rate (A or Z)- rate at which messages arrive at input side+

?+ ueue .i6e - .i6e o* the queue where the messages reside *or some time (until the channel "ecomes *ree)

@+ ueuing discipline (.ervice discipline)- way how the messages get process "y the channel+

+ $aiting Time (Tw)- Time spends waiting *or the transmission lines and the computer+D+ .ervice Time (Ts)- time required *or transmission o* message, processing "y the computer, printing and all

activities "y the user+

+ !hannel &andwidth (&)- &andwidth o* the channel+

MM1 u"u"% In >, *irst indicates that arrivals are independent o* one another that is inter'arrival

times are distri"uted eponentially+ The second indicates that the service times are also eponentiallydistri"uted+ The > indicates that > server is present+ ( stands *or arkovian a*ter the arkov)+

>)Arrival rate is the reciprocal o* the average inter'arrival time+ For eample- essage inter'arrival time is seconds then arrival rate is- >H messagesmin or (>) msgsec+

?) .ervice time (Ts) is the ratio o* message length to the channel speed+ !onsider messages are o* having @HHcharacters and transmitted on BHH "ps line+ Then the service time is- (Total no o* "its) (!hannel .peed in "ps)or L&+ Thus the T. "ecomes (@HH [ G) BHH @ sec+

@) The service rate is the reciprocal o* the service time+ (0>Ts)+ !onsider messages are o* having @HH

characters and transmitted on BHH "ps line+ Then the service time is- L&+ (@HH [ G) BHH @ sec+ The servicerate is the reciprocal o* the service time+ (0>@ msgsec)+

) The utili6ation o* the server is de*ined as the *raction o* time that it is "usy+ (7A0)+ I* the arrival rate is

> msgsec and service rate is >@ msgsec then the utili6ation o* the server is- H+D+ 7 is a dimensionlessquantity+ I* 7> then, Arrival rate and departure rates are same "ut in practice, 7 is never >+


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2ample>- essages arrives at a rate o* DHH "its per second and transmitted on a channel o* >HHH "ps+ !alculate

Arrival rate, .ervice Time, 0eparture rate, utili6ation o* the .erver, $aiting time etc+Answer- A =>> btss"c0 Ts >.= s"c0 D ! $s*s"c .". 1>>> btss"c0 U >.= and T >.= s"c

2ample?- The average inter'arrival time "etween messages is >H seconds and service time is D seconds+!alculate Arrival rate, departure Rate and utili6ation o* the server+

Answer- A >.1 $s*s"c0 D >.! $s*s"c and U >.=

MM! u"u"- In this there are two servers are availa"le+ $hen there are two or more messages in the system,"oth servers are "usy and the departure rate is twice as high+ 7tili6ation o* > queue is 7 while the

utili6ation o* ? queue is 7?+ 7 and A get dou"le *or ? queue with respect to their relative values in

the > queue+

MM$ u"u"% .uppose now there are m servers+ 0eparture rates increases as the num"er o* messages in the

system increases+ .ince the num"er o* "usy servers increases too, until the num"er o* messages is m+ Then allservers are "usy and the departure rate remains constant at m0+

Ty+"s o( u"u"%

>+ n- Arrival and service times are eponentially distri"uted+ ost widely used+

?+ 0n- Arrival is eponentially distri"uted and service time is deterministic+

@+ 9n- Arrival is eponentially distri"uted and service time is constant++ 99n- Arrival and service time processes are ar"itrary+ No mathematical solution and thus less used+

D(("r"nc" b"t""n Crcuts and Pac/"t Stc)n*%

Crcut Stc)n* Pac/"t Stc)n*Conn"cton There is a physical connection "etween

transmitter and receiver

No physical path is esta"lished "etween

transmitter and receiver+ Logical connection

is esta"lished in #! packet switching+

Pat) All packets uses the same path 1ackets travel on di**erent path+

ay"r Takes place at the physical layer+ 0atagram packet switching is done a

network layer while #irtual !ircuit packe

switching takes place at data link layer

A++lcaton Telephone Networks, odem !omputer, Internet

Ad&anta*"s 9uaranteed data rate and no delay in data *low+ Less "andwidth is used as message isdivided into small packets+ 2**iciency is

higher+Dsad&anta*"s !annot "e used to transmit any other data even

i* the channel is *ree+ 2**iciency is lower as it

reserves entire "andwidth in advance+

ore delay+


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UNIT IV F V

ADVANCED ROUTIN: I F II

Syllabus

Advanced Routing % I- Routing architecture, Routing "etween peers (&91), I1 switching and ulti' 1rotocolLa"el .witching (1L.), 1L. Architecture and related protocols, Tra**ic 2ngineering (T2) and T2 with

1L., NAT and #1N (L?, L@, and /y"rid), !I0R %Introduction, !I0R addressing, !I0R address "locks and

&it masks (G /rs+)

Advanced Routing % II- o"ile I1' characteristics, o"ile I1 operation, .ecurity related issues+ o"ility in

networks+ #oice and #ideo over I1 (RT1, R.#1, o.) I1v- $hy I1v, "asic protocol, etensions and options,

support *or o., security, etc+, neigh"or discovery, auto'con*iguration, routing+ !hanges to other protocols+Application 1rogramming Inter*ace *or I1v+ (G /rs+)

3.1 Routn* Arc)t"ctur"

A network router is a network device with inter*aces multiple networks whose task is to copy packets *rom one

network to another "ased on the routing ta"les stored in the memory+ Router will typically utili6e one or more

routing protocols, such as RI1, 3.1F, or &91+ Routers also accept routes which are con*igured manually "y anetwork administrator+ Those routes are called static routes+ The router will use this in*ormation to create a

routing ta"le+ The network router will then use its routing ta"le to make intelligent decisions a"out whichpackets to copy to which o* its inter*aces+ This process is known as routing+

Router has *our components- input ports, output ports, the routing processor and the switching *a"ric+

a) Input port per*orms the physical and data link layer *unctions o* the router+ The "its are constructed *rom the

received signal, packet is de'capsulated *rom the *rame, errors are detected and corrected+ The packet isready to "e *orwarded "y the network layer+ Input ports has "u**ers (queues) to hold the packets "e*ore they

are directed to the switching *a"ric+

") An output port per*orms the same *unction as the input port, "ut in the reverse order+c) Routing 1rocessor- The destination address is used to *ind the address o* the net hop+ Routing processor

searches routing ta"les+

d) .witching Fa"rics- It moves the packet *rom the input queue to the output queue+ In the past, memory o* thecomputer or a "us was used as the switching *a"ric+ The simplest type o* switching *a"ric is the cross"ar

switch which connects n inputs to n outputs in a grid, using electronics micro'switches at each cross point+


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The *unctionality o* the router is as *ollows-

17 Rout" Proc"ssn*% This includes routing ta"le construction and maintenance using routing protocols such as

RI1 or 3.1F etc+ The routing ta"les could "e created statically or updated dynamically+

!7 Pac/"t (orardn*% The router checks the received packet (checking header *ield, version num"er etc) and

calculates the header checksum+ The router also per*orms a ta"le lookup to determine the output port todirect the received packet and the net hop to which to send the packet along the route+ This is "ased on

destination I1 address and the su"net mask(s) o* the associated ta"le entries+ It could "e local delivery,

unicast delivery or could also "e multicast delivery+

-7 Pac/"t l("t$" control% The router ad:usts the TTL *ield in the packet header which is used to prevent

packets *rom circulating endlessly throughout the internetwork+ TTL value is decremented and packet will

"e delivered to the associated output port+37 C)"c/su$ calculaton%I1 header checksum must "e recalculated due to the change in the TTL *ield+

.ometimes I1 packets must also "e *ragmented "ased on the T7 (aimum Transmission 7nit) *ield+

=7 S+"cal s"r&c"s% 1acket translation, encapsulation, tra**ic prioriti6ation, authentication and access services

such as packet *iltering *or security*irewall purposes are also includes under this category+

3.! Routn* b"t""n P""rs

Intra and Int"rdo$an Routn*% An internet is divided into autonomous systems+ An autonomous system is a

group o* networks and routers under the authority o* a single administration+ Routing inside an autonomous

system is called intradomain routing+ Routing "etween autonomous is called as interdomain routing+

Routn* Al*ort)$s%Routing algorithms used in designing routing ta"les .tatic (Non'adaptive) or dynamic

(Adaptive)+ .tatic routing algorithms includes shortest path, Flooding and Flow "ased Routing+ 0ynamicrouting algorithms includes distance vector Routing and Link state Routing+ 0i:kstraXs Algorithm *inds the

shortest path *rom a starting verte to all other vertices in a graph+ $e start with node A, as the source and we

mark each node with an estimated distance *rom A to the node+ The initial estimates are in*inite, ecept that o*

node A which is H+ 2very incoming packet is sent out on every outgoing line ecept the line on which it isarrived+ 0isadvantage is that it generates a large num"er o* duplicate packets+ Tra**ic grows very quickly+ &y

using various damping techniques such as using a hop counter, to keep track o* the packets and selective

*looding could "e used+ Flow "ased algorithms uses topology and load condition *or deciding a route+ It ispossi"le to optimi6e the routing "y analy6ing using the data *low mathematically+ To use this technique, su"net

topology and tra**ic must "e known+

In distance vector routing,Router maintains a ta"le which gives the "est known distance to each destination and

the in*ormation a"out which line to "e used to reach there+ At each step- it receives in*o *rom neigh"or,

computes the "est path and possi"ly send new in*o to ad:acent neigh"ors+ 0istance vector tells their neigh"ors

what he knows a"out everyone while Link state tells everyone what he knows a"out his neigh"ors+ In L., 2achrouter should discover its neigh"ors, measure cost, construct a packet (L.1) and sends this to all routers and

compute the shortest path+

RI1 is Routing In*ormation protocol+ In this, routing updates are echanged "etween neigh"ors appro+ every

@H seconds using RI1 response message+ This message contains a list o* ?D destination network within an A.+ A


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router can also request in*ormation a"out its neigh"ors cost to a given destination using RI1 request message+

3.1F stands *or 3pen .hortest 1ath First 1rotocol+ It is called as Internal 9ateway 1rotocol, "ecause it supportsrouting within one A.+ 3.1F is Link state routing protocol where Link state advertisements are sent to all other

router within the same area+

1ath #ector Routing- 1ath vector routing is similar to distance vector routing+ There is at least one node, called

the speaker node, in each A. that creates a routing ta"le and advertises it to speaker nodes in the neigh"oring

A.s+ &91 is "ased on 1ath #ector Routing+ &order 9ateway 1rotocol (&91) is an interdomain routing protocol

using path vector routing+ It *irst appeared in >

acn - subject notes

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