ࡱ> wvY( / 0DTimes New Romand0Wo 0 DWingdingsRomand0Wo 0  DArialngsRomand0Wo 0 " ` .  @n?" dd@  @@`` H(!!     c $@uʚ;2Nʚ;g4BdBd0pppp@ <4!d!d 0LP <4dddd 0LP  RJ___PPT9,$<,4dd<@"8#H,,,DD?T-3/3/2004 (Hanoch Levy, CS, TAUO =N!What Quality of Service is About " Hanoch Levy Feb 2004   Outline  lWhat is Quality of Service on the Internet about What the aims of this workshop Structure of the course mm=The Users and the service: What Communications Network serve >>User A and User B Placed in different locations Want to pass data of some type, from one to another. Want this to be done good/best/ASAP. Want to do it with certain minimal quality requirements.  2The Users and the service: The user point of view 33The single User is at the center of focus User is interested in getting the quality / performance it wants Selfish: User does not care about other users!! 0n+The Scarce Resource problem Resources are (are nt?) limited Giving the user as much as it needs/ wants may be difficult due to limited resource problem. Subjects where there is not resource limitation  do not face Quality of service problem. )The Scare Resource problem: Does it exist$*)(Are car-road resources limited? Definitely, At least at large fractions of the day. Are Network resources limited: Open question A debated question A subjective question: (cost-wise? Indirect-cost? Damage?) t!5!]!5!]#=The Scarce Resource problem: A Moving Target / Relative issue$>=(Technology and economics are changing Technology LEAPS: Open bottlenecks Move bottlenecks / create bottlenecks Examples: Widening a major road removes traffic jam on road and create one in the city entrance. Creation of WEB on mid 90 s: Makes access to WEB servers easy Creates traffic jams on the internet. The hot issue of today, is not that of tomorrow 8ZBZtZKZ1Z8BtK  1h$ >The Scarce NETWORK Resource problem: Does it exist? - revisit $?>(6Late 90 s: Telecomm boom: Massive investment in infrastructure, especially at long distance Many claim: today a lot of  bandwidth in the ground No resource problem for communications. Really? Access networks? Still may be a problem Wireless networks? Can be a major problem. xZZTZZBjT%!8The Scarce NETWORK Resource problem: Does it exist? (3) $98(Note:  no problem of long distance due to major economics investment  wireless problem due to technological leap in wireless X}_ 1Communications Network and QoS :The network angle22The network serves MANY users The network aims at providing good/Best quality to all of its users. The network must account for the needs of all users and achieve a mechanism that can meet them.  1Communications Network and QoS :The network angle22Communications Network is like a set of car roads Communication applications are like streams of cars. QoS deals with how to operate these roads in order to provide the cars with good quality of service.0How does it look like: the network from 10K feet11 4The User perspective / The application perspective 55'Given the set of traffic rules used by the network user/ application want to: Get the quality it wants As good as possible? Good above certain quality? Pay as little as possible to get that quality. User probably does not care about: Other users (their quality) Fairness to other users. O" " 3" 0" $" 8" O30$8  4The User perspective / The application perspective 55tThe application: May care or may not care about other users / their  fairness , etc. This depends with what perspective the application was built. Social objective / or : Selfishness l" " %" %6The eternal race between the network and the users 77MThere is an eternal race/game between the network and the users. Network set up rules of operations Users try to exploit them Go back to 1. (Sometimes: technology change, and goto 1) The tighter the rules of operation the less freedom the user has. The tighter the rules of operation the better quality is granted to the users. zA" Zx" Z" ZZAx:Tightness of operational rules: example1 : Car traffic ;;The Transport (car) system Semi loose system One CAN drive 200 KM/Hour One Can cross red lights One can drive on sideway / and/or abuse lanes getting better performance one s car on the account of others. Still rules are strict enough One cannot really do it for long time Where is the looseness: Rules are strict Enforcement less strict. " Z" Z" Z" Z?" Z," ZbE?  ,O:Tightness of operational rules: example1 : Car traffic ;;Most abuse is on speed / priority at junctions No abuse at volume (bandwidth): No limitation on the number of cars one can buy and send into the street. Reason: Not really necessary Car is so expensive  one cannot really send many cars in (bottleneck in the car supply!). Q: what will happen if car cost drops by factor of 5? (This is what happened to communications costs!!) Probably increase, but then flatten (hard to drive 2 cars concurrently!)O" ZS" Zp" Zh" ZI" ZOSph  I7Tightness of operational rules: Example2: Telephony 88The Telephone system (non cellular) Very strict system: User has almost NO CONTROL of how application behaves User has almost no control of the resources she gets from the network User gets VERY GOOD QUALITY What happens if phone cost drops by factor of 5? Talk more& (perhaps not 5 times more). And then flatten out (cannot talk to 10 people concurrently!!) $" Z" Z1" Zg" Z$1g6Tightness of operational rules: Example3: Internet 77The Internet system Quite loose system ( freedom ): Application has some freedom in the traffic it introduces to the network The way it sends the data (later) The user has freedom in how / how much it uses the application: One can send as much email as one wants. One can hit the browser button as hard as one wants. One can download songs 24 hours a day. " k" #" A" " " k#A    &"Tightness of operational rules: Is  freedom (Internet) good? AAThe  unlimited resource paradox: How long can an unlimited resource remain unlimited? In theory  perhaps long In practice: Very few resources remained unlimited for long time. Road? Never! Food? Even bread hardly! Water: almost never (cost of shipping) Air? p"" " S"S  '#3What happens if we get 5 times more the service 44If car prices drop by factor of 5? Probably drive more But then flatten  cannot drive 2 cars concurrently If telephone costs drop by factor of 5: Probably talk more. But then flatten -- cannot talk to 10 people concurrently If Internet price goes down by factor of 5 (or Bandwidth goes up by factor of 5): We can use quite a bit of it And when we reach our limit: Probably new applications (High definition TV, 3D movies, Monitor your kid/pet/refrigerator/& . @$" ZI" Z(" ZP" ZT" Z" ZZ I PB  Objective of this workshop  To study and understand the quality of service issues of the Internet. Understand the QoS problems Understand the mechanisms that are used / can be used to provide QOS. Create these mechanisms @" |I+Methodology and contents of the course ,,Theoretical background  will be provided at class. Practical experience  at the lab. Take the user ( abuser ?) perspective: Given the network and the network rules, client aims at maximizing its performance. What can client do / how should client operate. z" " " 'Methodology : Project description ((You have a client and your objective is to transfer (receive) X files from the network. The files are distributed over N locations. Some may appear in multiple locations. The rate of downloading the files may depend on several parameters, some under your control. ^" "  'Methodology : Project description 2 ((wYour aim is to download the files to your best satisfaction: As fast as possible At lowest Bandwidth consumption(?) ^>" 8" >8!,Methodology : Project description Part I --You are given both the client and the server You aim at building a mechanism (protocol) that will transfer from server to client at maximum  efficiency Only minimize time Also minimize lost resources (lost packets) " Z@" Z" ZZ@   "-Methodology : Project description Part II ..You are given the client only K Servers are given and they operate according to their protocol (FTP) Want to download the files efficiently from the servers Only minimize time Also minimize lost resources (lost packets) " Z@" Z" ZZ@   .QOS Problems of Interest For network designer //Traffic classification and characterization Properties of traffic (many to choose from) Requirements of the application / traffic Requirements of the system Impact on the system 0," , QOS Problems of interest (cont):!!2. Policing and shaping Monitor traffic for obeying the rules Location: typically at network entrance 3. Node ( Intersection ) design: Create fast intersections Introduce mechanisms of prioritization into the intersections Guarantee QoS to a traffic stream despite interference of other streams (fair queueing) Location: In the nodes ZQZ"ZZQ"2b  QOS Problem of interest (cont)  4. Do not overflow your nodes (intersections)  estimate node capacity (Call Admission Control) 5. Efficient navigation of traffic (Routing) while obeying QoS 6. Managing your traffic: Virtual paths (transform your cars into trains& )^H'. $ QOS Problem of interest (cont)g7. Coordinate through network nodes (reservations): Traffic engineering. 8. Traffic characterization. Zg1 ` ` ̙33` 333MMM` ff3333f` f` f` 3>?" dd@,|?" dd@   " @ ` n?" dd@   @@``PR    @ ` ` p>> $(    6 P  T Click to edit Master title style! !  0,"   RClick to edit Master text styles Second level Third level Fourth level Fifth level!     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(3) 2Communications Network and QoS :The network angle2Communications Network and QoS :The network angle1How does it look like: the network from 10K feet5The User perspective / The application perspective 5The User perspective / The application perspective 7The eternal race between the network and the users ;Tightness of operational rules: example1 : Car traffic ;Tightness of operational rules: example1 : Car traffic 8Tightness of operational rules: Example2: Telephony 7Tightness of operational rules: Example3: Internet ATightness of operational rules: Is freedom (Internet) good? 4What happens if we get 5 times more the service Objective of this workshop ,Methodology and contents of the course (Methodology : Project description (Methodology : Project description 2 -Methodology : Project description Part I .Methodology : Project description Part II /QOS Problems of Interest For network designer !QOS Problems of interest (cont): QOS Problem of interest (cont) QOS Problem of interest (cont)  Fonts UsedDesign Template Slide Titles_㈻anatanat  !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]_`abcdeghijklmopqrstuxRoot EntrydO)Current UsernSummaryInformation(^PowerPoint Document(DocumentSummaryInformation8f