CSC461-CN-Lecture-11-Feb.-4-2013

7/28/2019 CSC461-CN-Lecture-11-Feb.-4-2013

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BITS PilaniPilani | Dubai | Goa | Hyderabad

Network VirtualizationLecture - 11, February 4, 2013

Rahul Banerjee, PhD (CSE)

Professor, Department of Computer Science & Information Systems

E-mail: [email protected]



BITS Pilani, Deemed to be University under Section 3 of UGC Act, 1956

• Network Virtualization

• Network-based Virtualization

• Current State-of-the-art and Evolving Research

Directions• From Clusters and Grids to Clouds

• Wearable Computing

• Ubiquitous or Pervasive Computing

• Select References to the literature • Summary

Interaction Points




• LAN Virtualization:

– LAN Emulation

– Virtual LANs (VLANs)

• WAN Virtualization: – WAN Emulation

– Virtual Private Networks (VPNs)

• OvertheInternet

• OverNon-InternetInfrastructure

• Sub-IP-levelVPNs

• IP-levelandHigherLevelVPNs

Network Virtualization




• What is a VLAN?

• How can we create a VLAN?

• Benefits of a VLAN

• Disadvantages of a VLAN

• Types of Contemporary VLANs

• VLAN Standards• IEEE 802.1q

• VLAN Tagging & Trunking

Virtual LAN (VLAN)




• What is LAN Emulation?

• When do we do LAN Emulation?

• Examples of LAN Emulation

• Advantages of LAN Emulation

• Disadvantages of LAN Emulation

• LAN Emulation versus LAN Simulation

LAN Emulation




• Need for WAN Virtualization• Contemporary practices involved in WAN

Virtualization – Public WANs

• Examples:TheInternet,TheNKN – Private WANs

• Examples:TTSL,TC,RelianceWANs

– Virtualized Private WANs / Virtual PrivateNetworks

• Examples:BITS-Connect2.0MPLS-VPN,BITSERPMPLSVPN

WAN Virtualization


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Network-based Virtualization



OfClusters,GridsandClouds• Networks:

– Asetofautonomouscompute/communicaQonnodesinterconnectedforthepurposeofmeaningfulresourcesharing,requiresupporQngprotocolstacks,not

transparenttotheusers

• Clusters

– Homogeneous(plaorm/OS),allinvolvednodesoenbelongtoasingleenQty

andfrequentlydesignedforhigh-performancecompuQng,maybelimitedtooneormorerackswithinthesameroom(example:HPCclusters),easiesttodeploy

andmanage

• Grids

– Oenheterogeneous(plaorm/OS),FrequentlyspreadovermulQplenetworks

andnetworktypes,mayinvolvesingleormulQpleorganizaQons,requiregreater

effortindeploymentandadministraQon

• Clouds

– Maybepublic,privateandhybrid,supportmulQplelevelsofabstracQons/

virtualizaQon,typicallyspreadoverwideareas,expectedtobetransparenttothe

user,offerthehighestlevelsofredundancy/availability,

F e b r u a r y 4

, 2 0 1 3

( c ) D r .

R a h u l B a n e r j e e ,

B I T S P i l a

n i

, I N D I A



Afewpointsofsignificance

• VirtualizaQonistheunderlyingcommontechnologyinvolvedinallthethreeparadigms

• Networkingisthekeyenableringredientineach

ofthesecases

• Cost-effecQveness,robustnessandscalability

improveaswemovefromclustertocloudbut

overheadsandinternalcomplexityaddup

F

e b r u a r y 4

, 2 0 1 3

( c ) D r .


B I T S P i l a

n i

, I N D I A



TypesofClouds&Associated

VirtualizaQon

• TypesofClouds:ClassificaQon-1<basis:modelofoperaQon>

– PublicClouds(mulQ-tenancy,widevariaQons,mulQ-

service,on-demandcapacityaddiQonacommonfeature)

– PrivateClouds(singletenancy,limitedvariaQons,higher

capitalinvestments,greatercontrol,moresecure)

– HybridClouds(near-opQmalbestofbothworlds,if

configuredwell)

•

TypesofClouds:ClassificaQon-2<basis:devicevirtualizaQon>

– InfrastructureCloud,ComputaQonalCloudetc.

• TypesofClouds:ClassificaQon-3<basis:servicevirtualizaQon>

– Plaormasaservice,Sowareasaservice,Storageasa

service,CollaboraQon&SharingServicesetc.

F

e b r u a r y 4

, 2 0 1 3

( c ) D r .


B I T S P i l a

n i

, I N D I A



Case-StudyofofaNetwork-BasedMulQ-siteCollaboraQonSystemDesign


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Project BITS-Connect 2.0



WearableCompuQngElements

February4,2013 (c)Dr.RahulBanerjee,BITSPilani,INDIA



E-FabricofaWearableGarment




Paradiso&Starner’sShoes<1995>for

ElectricalEnergyGeneraQon




PervasiveCompuQngwithAR




References

• Larry L. Peterson & Bruce S. Davie: Computer Networks: A Systems Approach,Fifth Edition, Morgan Kaufmann / Elsevier, New Delhi, 2011. <System designapproach>

• S. Keshav: Computer Networking: An Engineering Approach, PearsonEducation, New Delhi, 1997.

• A. S. Tanenbaum: Computer Networks, Fifth Edition, Pearson Education, NewDelhi, 2012. <Conceptual Approach>

• Y. Zheng and S. Akhtar: Networks for Computer Scientists and Engineers,Oxford University Press, New York, 2002. <Structural approach>

• A. Leon Garcia and I. Widjaja: Communication Networks: FundamentalConcepts and Key Architectures, Second Edition, Tata McGraw-Hill, New Delhi,2004.

• Mohammed G. Gouda: Elements of Network Protocol Design, Wiley Student

Edition, John Wiley & Sons (Pte.) Ltd., Singapore, 2004.• Thomas G. Robertazzi: Computer Networks and Systems: Queuing Theory and

Performance Evaluation, Third Edition, Springer-Verlag, New York, 2000.<Analytical approach>

04/02/13 (c)Dr.RahulBanerjee,BITSPilani,INDIA 17



What is next?

Subsequentlecturesshallintroduceyoutothefollowingtopics:<notinthesameordernecessarily>

• Topologiesinvolved

• Performance

• ualityofService

• Reliability

• Security

• ProtocolsandMechanismsinvolved

• MethodsofSimulaQon

• Sengupaphysicalsystemandconfiguringit

• NetworkAnalysis




References

• Larry L. Peterson & Bruce S. Davie: Computer Networks: A Systems Approach,Fifth Edition, Morgan Kaufmann / Elsevier, New Delhi, 2011. <System designapproach>

• S. Keshav: Computer Networking: An Engineering Approach, PearsonEducation, New Delhi, 1997.

• A. S. Tanenbaum: Computer Networks, Fifth Edition, Pearson Education, NewDelhi, 2012. <Conceptual Approach>

• Y. Zheng and S. Akhtar: Networks for Computer Scientists and Engineers,Oxford University Press, New York, 2002. <Structural approach>

• A. Leon Garcia and I. Widjaja: Communication Networks: FundamentalConcepts and Key Architectures, Second Edition, Tata McGraw-Hill, New Delhi,2004.

• Mohammed G. Gouda: Elements of Network Protocol Design, Wiley Student

Edition, John Wiley & Sons (Pte.) Ltd., Singapore, 2004.• Thomas G. Robertazzi: Computer Networks and Systems: Queuing Theory and

Performance Evaluation, Third Edition, Springer-Verlag, New York, 2000.<Analytical approach>

© Dr. Rahul Banerjee, BITS, Pilani (India)04/02/13 (c)Dr.RahulBanerjee,BITSPilani,INDIA 19




ArchitectureoftheInternet1of2

• Brief Historical Notes:

– Initiated by the US Department of Defense (DoD) through its Advanced Research Project Agency (ARPA) and was hence called ARPANet.

– Originally, it was a point-to-point WAN involving only four nodesacross the USA.

– Original architecture that led to ARPANET has evolved over the years

that have passed by. – In later years, ARPA / DARPA dissociated with it and allowed to this tobe blossomed into the Global Public Internet as we see it now.

• Current Status: – It is loosely hierarchical.

– Has no single body that owns it or rigidly controls it. ---Mostly run through volunteer efforts and by consensus.

– Runs several services, in a distributed manner, includingthe immensely popular World-Wide Web.

– Is helped by global cooperation including those from

governments and corporates apart from academia




ArchitectureoftheInternet2of2

•

Currently, Internet architecture is designed for the best-effort delivery and is largely governed by the IAB of theInternet Society (ISoc). – ISoc has many sub-organs which facilitate evolution and

coordinated maintenance of the Internet. – IESG steers the ISoc in a general way the engineering issues

are resolved. – IETF workgroups do the ground work and by a democraticprocess helps community in building up engineering solutionsthrough IETF drafts and standards (RFCs) etc.

• Currently, the TCP/IP stack is the dominant protocolstack over which the Internet runs.

• Keeping the needs of expansion and improvement, thisprotocol family has continually evolved over last 30+years. – Current version of IP is IPv6, although IPv4 is still dominant in

use.




WhatistheInternettoday?

• Wide Area Network of variety of networks• Global

• Public• Not transparent, as yet

• Hybrid topology but largely hierarchical• No single controller

• Internet Society (ISoc) oversees, assists ---does not control

• QoS, Security continue to have issues – partly atleast

• Web, mail, commerce, education, entertainment,sharing continue to dominate its applicationspace




Project BITS-Connect 2.0

The Immersive Tele-presence Rooms

•

This is how an18-seater

immersive tele-

presence room

looks like at all

the Indiancampuses.

• Chancellor’soffice

isequippedwith

onetwo-seatersystem



(c)Dr.RahulBanerjee,BITS,Pilani,India

24

A Few More Networking Terms

•

Repeaters / Repeater Hubs / Shared Hubs: where usually Physicallayer / level exist with L1-protocol data unit (raw bits) regeneration andonward transmission

• Managed Hubs / Layer-2 Switching Hubs: where Physical and Data Linklayers / levels exist with ability to handle and deliver Layer-2-protocoldata unit (frame)

• Bridges: where Physical and Data Link layers / levels exist with L2-

protocol data unit (frame) processing and forwarding• Switches: where Physical and Data Link and / or Network (sometimes

even higher) layers / levels exist with Layer-2 and / or Layer-3-protocoldata unit (frame / packet) processing, switched routing / forwarding

• Routers: where Physical and Data Link and Network layers / levels existwith L3-protocol data unit (packet) processing, routing and forwarding

• Gateways: where two or more different networks meet and may requireprotocol / message translation capabilities

• Clouds: abstraction of node connectivity in the networking context<details hidden>



Frames:LinkLayer(L-2)DataUnits

• Frame• TheunitofDataasexpressedattheDataLinkLayer

(Layer-2oftheHypothe0calmodelusedforinstruc0on)isconvenQonallycalledaFrame.

• FramescantakedifferentformatsandsizesdependingupontheprotocolinquesQon

• FramesdoincludefieldslikesynchronizaQon,addressing,payload,control-informaQonetc.

• FrameForwarding• Theprocessofmovingframesfromoneporttoanotherina

bridgeorswitch.

25 (c) Dr. Rahul Banerjee,BITS, Pilani, India



Frames:Factorsthatmaer!

• Synchronization: Transmitter & Receiver need tobe in sync

• Start Delimiter: Required to mark starting bit

• End Delimiter: Required to mark the end bit

• Control Information: Information suggesting datahandling and interpretation

• Error Detection / Correction / Retransmission

• Flow Control: Required for avoiding data lossdue to overflow at receiving end

• Data Length: Needed if data-field is not of fixedsize

26 (c) Dr. Rahul Banerjee,BITS, Pilani, India



LogicalViewofa10-GbpsUnit

hp://www.ovislinkcorp.co.uk/linkd.GIF

7 1 6 6 2 46=<15

00 4

Pre SFD DA SALengthType

Data unit+ pad

FCS

FrameStructure-10GigabitEthernet(IEEE802.3aeforLAN,WANandMAN)

ItusesthesameMACframeastheEthernet.

hp://www.javvin.com/pics/10GigE.gif&imgrefurl=hp://www.javvin.com/protocol10GigE.html&usg=__VuNx4T-UphUAzm-

_AEsDqMqvzL=&h=374&w=576&sz=34&hl=en&start=10&um=1&itbs=1&tbnid=JlvKsLiP2xuOfM:&tbnh=87&tbnw=134&prev=/images%3Fq%3Dgigabit%2Bethernet%26hl%3Den%26safe%3Doff%26um%3D1



SummaryofDifferencesBetweenL-2Switches,

Routers(L-3)andL-3Switches

• BridgesandLayer-2switchesdividethe

networkintosegmentsormicro-segments

(apartfromhelpinginLayer-2protocol

translaQon,management,securityetc.)

• Ineffect,wecansaythat

– Layer-2Switches/Bridgesseparatecollision

domains

– Layer-2Switches/Bridgescancarryoutprotocol

translaQons

04/02/13 (c)Dr.RahulBanerjee,SDETUnit,BITS-Pilani,INDIA

28





• RoutersareLayer-3deviceswhohandleLayer-3packetrouQngwithinand

outsidethelocalnetwork/internetworkandthereforeeffecQvely

separatebroadcastdomainswhichendatitsdifferentnetworkinterfaces

eachofwhichcarriesaseparateSubnet-idenQfier/Subnet-address(apart

fromLayer-3protocoltranslaQon,monitoring,securityandmanagement)

• Thus,ineffect,wecansaythat:

– RoutersSeparatebroadcastdomains(eachofsuchbroadcastdomainswhich

endatitsdifferentnetworkinterfaceseachofwhichcarriesaseparate

Subnet-idenQfier/Subnet-address)

– RouterscancarryoutinteriorrouQngand/orexteriorrouQng,depending

upontheirlocaQoninthenetwork – RouterscancarryoutprotocoltranslaQons(intermsofprotocol-specific

packetformatsaswellasintermsofallowingappropriatelyformaed

selecQvedataspecifictorouQngprotocolstheymaysupport).


29





• Layer-3switchesaredeviceswhichcanhandleallfuncQonaliQesofLayer-2Switchesaswellasfast(oenbasedonheader/tag/labelswitching)Layer-3

packetrouQngwithinbutnotoutsidethelocalnetwork/internetwork;and

therefore,effecQvelyseparatebroadcastdomainswhichendatitsdifferent

LANinterfaceseachofwhichcarriesaseparateSubnet-idenQfier/Subnet-

address(apartfromopQonalLayer-3protocoltranslaQon,monitoring,securityandmanagement)

• Thus,ineffect,wecansaythat:

– L-3SwitchesSeparatebroadcastdomains(eachofsuchbroadcastdomainswhich

endatitsdifferentLANinterfaceseachofwhichcarriesaseparateSubnet-

idenQfier/Subnet-address) – L-3SwitchescancarryoutfastinteriorrouQng/packet-switchingoenbasedon

header/tag/labelswitching

– Layer-3Switches,opQonally,cancarryoutprotocoltranslaQons(intermsof

protocol-specificpacketformats).


30



InsideaLayer-2Switch

• ElementsofaLayer-2Switch

– Processors(Front-endProcessorsonLineCards)for

FrameRouQng

– MulQpleBuffersforMulQpleueues

– SharedI/OBusorRing(1st/2ndGen.)/Switching

Fabric(3rdGen.)

– I/PLineControllers(ILC)

– O/PLineControllers(OLC)

31 (c)Dr.RahulBanerjee,BITS,Pilani,India



SomeMoreTermsofRelevance• Collision Domain

– The set of all stations connected to a networkwhere faithful detection of a collision can occur.

– A collision domain terminates at a switch port.• Late Collision

– A failure of the network in which the collision

indication arrives too late in the frametransmission to be automatically dealt with by themedium access control (MAC) Protocol.

– The defective frame may not be detected by allstations requiring that the application layer detectand retransmit the lost frame, resulting in greatlyreduced throughput.

• CRC

– Cyclic Redundancy Check is an error-checkingtechnique used to ensure the fidelity of receiveddata.

32 (c) Dr. Rahul Banerjee, BITS, Pilani, India




• Current State-of-the-art and Evolving Research

Directions

• Sensor Networks

• Wearable Computing

• Ubiquitous or Pervasive Computing

• Select References to the literature

• Summary

Interaction Points



WirelessCommunicaQoninWearables




UserInterface&Sensors




(c)Dr.RahulBanerjee,BITS,Pilani,India 37

IntroducingSomeTermsRelatedtoNetworks

• Channel <application-level logical / virtualcommunication path>

• Services: Functionalities provided by a layer /protocol / entity

• Interfaces: Peer-to-Peer / Layer-to-Layer / entity-to-entity

• Service Access Points: defined addresses / portsthrough which data / parameters are passed

• Tunneling <Encapsulation & Decapsulation>



What do we mean by a Network

Protocol? – Perspective-1:

• A Network Protocol is a set of rules and conventionsleading to a set of pre-defined requests / commandsand responses for any meaningful communication /exchange of control / information / both

– Perspective-2:

• A Network Protocol may also be viewed as abstractinterfaces in terms of operations associated with aninterface definition in the context of one or moreservices on offer along with the set of parameters,form, format, message types, meanings associatedwith the messages and even mechanism of handling

select kinds of possible failures. – Perspective-3: • A Network Protocol may be seen as a pair of modules

implementing the interfaces between two layers or peers

(c)Dr.RahulBanerjee,BITS-Pilani,INDIA



ProtocolGraphs

• A graph showing interrelation of various collaboratingprotocols at different levels is called a Protocol Graph.

• In a protocol graph, each protocol is represented as anode.

HTTP

TCP UDP

IP

TFTP



ExampleofaSimpleProtocol

GraphasapplicabletotheInternet

HTTP FTP TFTP

TCP UDP

IP



ProtocolRepresentaQon

• There exist numerous schemes of

representation of a given Protocol.

• One common way to specify a Protocol is

to represent it as a State Transition

Diagram.



ProtocolValidaQon

• A Protocol needs to be proven correctbefore it is implemented.

• There exist quite a few ways of formal and

semi-formal verification of Protocols.• One common technique is to first

represent a protocol a State Transition

Diagram and then examine it for its‘completeness’, ‘reachability’ and / or points of weakness etc.



AnExampleProtocol

• Let’s take one of the simplestsituations in which there exist twonetwork nodes N1 and N2interconnected through a bi-directional communication link.

• Let’s assume that that it isrequired that primarily N1 wouldbe sending the data to N2 using asimple mechanism over this linkand only one unit of data (frame)would travel at a time over thelink.



(c)Dr.RahulBanerjee,BITS,Pilani,India 44

AFewMeasuresofNetworkPerformance

• Performance Measures – Available Performance – Measured Performance

• Bandwidth: – Width of the usable / allotted Frequency band

– Rate of data transfer in bits per second • Throughput: Actual measured rate of achievable data transfer in

bits per second

• Bandwidth has often a value greater than that of the Throughput

• Round-Trip Time (RTT)

• Latency: Delays of various kinds• ‘ Delay x Bandwidth’ metric

• Quality of Service



NetworkArchitecture&ReferenceModels• Architecture versus Reference Model: A

simplistic perspective: – Network Architecture:

• It may be seen as a detailed generic blueprint withunambiguous definitions of services, interfaces,organization and defined protocols that helps in design

and implementation of a set of relevant protocol stack /suite based network / internetwork

– Network Reference Model:

• It is the same as the architecture minus the specificallydefined readily usable protocols.

• Examples: – TCP/IP Architecture

– OSI Reference Model & OSI Architecture

CSC461-CN-Lecture-11-Feb.-4-2013

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