n Based on unrealistic growth forecast n Overcapacity: Fiber 5x100 in three years n Wireless: Expensive spectrum licenses n Fibers

Transcription

1 EECS228a Research Topics Jea Walrad of Networks Walrad 52 of Networks Pricig of Services Competitio of Users Competitio of Providers Suggested Readigs: of Networks Bubble: Wired Walrad 53 Walrad 54 of Networks Bubble: Wireless of Networks Over-Ivestmet Based o urealistic growth forecast Overcapacity: Fiber 5x100 i three years Too may compaies competig for same market Debt Wireless: Expesive spectrum liceses Fibers IT i compaies: PCs, Servers, Networks Walrad 55 Walrad 56 1

2 Key Ideas Value of Services Value of services to users: exterality, QoS, CoS Market segmetatio Flat rate pricig; cogestio pricig; Paris metro pricig; time-of-day pricig Icetive compatibility Iter-ISP settlemets; Peerig agreemets Iteret as a public good Walrad 57 Exterality: Kazaa Value per bit: vs. fax vs. picture Value of bit rate: video stream vs. radio Value of low latecy: video stream vs. video coferece Value of low respose time: browsig with DSL vs. browsig with 56k QoS affects value ad usage Value of QoS depeds o applicatio ad user Walrad 58 Market Segmetatio Busiesses vs. Residetial Customers Network Applicatio Providers vs. public Web Sites Priciple: Charge more users with higher utility Differetiated Pricig Examples: First Class & Ecoomy i plae: More space but much more expesive Paris Metro: More expesive Fewer Users Better Service (e.g., Staford vs. Berkeley?) Suggests Class of Service: Better service by mechaism: e.g., priority Better service by fewer users: e.g., expesive etwork; cogestio pricig (e.g., packet markig); time-of-day Alterative: QoS: You kow what you pay for Service Level Agreemet (implemetatio?) QoS of accepted calls: ed-to-ed test Walrad 59 Walrad 60 Icetive Compatibility How to discover the user s willigess to pay? Examples: Califoria Electricity: Providers offer bids ad CA buys cheaper first prices escalade Highest bidder auctio: Spectrum auctios Highest gets but two highest pay Secod highest price: Icetive compatible Competitio Basic supply ad demad: More capacity tha traffic prices drop ad providers go bakrupt Iteret traffic doubles every year istead of every 100 days. Quality service is still rare ad valuable: Busiesses use video coferece over ISDN Expesive commutes ad busiess travel Users pay a lot for CATV ad pay-per-view T1 service expesive: demad exists Walrad 61 Walrad 62 2

3 Game Theory Framework to aalyze result of iteractio of self-iterested agets Suggests strategies for Pricig services Peerig agreemets QoS defiitios Evolutio of idustry (e.g., cosolidatio vs. specializatio) Two parts: Games & Mechaism Desig Graularity Types Walrad 63 Walrad 64 Reduce delays: Avoid OAK NY SF Improve reliability: Protectio Sesor etworks: May ope questios Ad Hoc etworks: More robust, provide QoS IP/Optical: Improve coordiatio Graularity Light Path: WDM Cross-Coect: SONET Circuit: Telephoe Label Switched Path: MPLS; ATM Coectio Packet Walrad 65 Walrad 66 Graularity (cot) Beefit of LSP vs SONET is ot obvious: Cosider traffic from SF to NY; If that traffic is essetially costat, the SONET is good eough. If ot, LSP/SONET is preferable. If traffic is self-similar, the fluctuatios persist at high rate Walrad 67 Types O-lie vs. Off-lie Cetralized vs. Distributed Lik State; Distace Vector; Path Vector Source-based vs. Destiatio-based QoS routig Ad Hoc; Locatio-Based At-routig (reiforcemet) Uicast vs. multicast Protectio routig Peer-to-peer vs. overlay Walrad 68 3

4 Beefits Implemetability: Scalability: commuicatios required; complexity; covergece time Robustess: sesitivity to errors Examples Walrad 69 Walrad 70 At user level: with QoS At etwork level: Losses, iefficiecy, ufairess At switch level: Scalability problems Examples TCP Cogestio i routers Call Admissio Cotrol Walrad 71 Walrad 72 Fairess vs. Optimality Simplicity Robustess Why bother? Trasactios Packet flows Walrad 73 Walrad 74 4

5 Why Bother? Network should be robust; ot based o detailed traffic assumptios Traffic characteristics impact Effectiveess of multiplexig Buffer sizes required Time scale of badwidth allocatios Trasactios File trasfers: File sizes: Heavy tailed Timig of requests: Poisso Geography: w Kazaa poor locality w Akamai improved locality Other applicatios: video cofereces VoIP Walrad 75 Walrad 76 Packet Flows Self-Similarity: Heavy Tail + TCP Self Similar Flows Heavy Tail Files + Structure of Web Sites Self Similarity Relevace: Not obvious a matter of time scale Walrad 77 5