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Worse case: massive congestion, network partitions, data / service unavailability Scrutinize infrastructure scalability Re-examine system level primitives Control traffic, fault-detection, replication overhead Dampen impact of operations on infrastructure Localize bandwidth / storage requirements, faults.ZuZ&Z#Z7Z.Z2Z.u&# 7 .2Highly DynamicIt s here& Small half-life for P2P apps (leeching) Connectivity loss from congestion, flash crowds, misconfiguration, hardware faults, lower MTBF BGP convergence 3-15 mins Mobile clients in semi-connected mode E.g. chatting / file-sharing on your IPAQ / Palmn &1 (_&1 ,d3X Implications of ChangeHave to reexamine stability assumptions Overlay maintenance under instability Without care, worst case: sub-optimal paths, network partitions, broken invariants loss of availability Proactive overlay construction and maintenance Integrate optimal routes from square 1 Estimate global knowledge w/ distributed algorithms at node insertion Run-time heuristics are too late Constant fault-detection and self-repair Use of redundancy to mask self-repair(ZZ/Z'ZgZ)Z&Z(@ ./'  g  )&Extending Scope of OverlayszBroader utility than file storage and retrieval General routing layer (efficiency, fault-tolerance) Detour, RAMP, RON, Tapestry Flexible data dissemination layer overlay multicast, anycast, mobility Collaborative applications Shared annotations, mail filtering Data transcoding Shared workspaces, games Distributed computation Barter incentives (Mojos, ads, access to resources)0Z4ZZ"Z%ZZeZZ"Z04"%  e",  Introspective Tuning for RealityGExploit knowledge of the environment Network latency discontinuity Order of magnitude latency jump from LAN to WAN Generic solution: Brocade: minimize wide-area hops via 2nd overlay Non-uniformity in node resources PDA < laptops < desktops < servers Segregate supernodes, infrastructure routers, pure clients, storage devicespCs"pCh  "p  GMany Security ChallengesOpen P2P = Infrastructure for attacks? Misreporting data unfair resource allocation DDoS attacks on infrastructure Sybil attack enabling scale for attacker Detecting maliciousness made harder Scalable defense? Cryptographic methods for authentication, privacy, etc. Byzantine agreement Redundancy (ID aliasing, multiple namespaces) Misuse leads to resource based DDoS Access control?'ZyZ$ZZ{Z$ZZ'< $  {$,V/  ` 33333u333ß̙` &L333333x&-LYMMM` ___333___` &L.i~333Ȫn̙}` 7NRLF333đwjg_MMM>?" dd@,? " Ud@ nF $ @`" d n?" dd@   @@``PR    @ ` `p>>0  0(  0 0 fQLA Large confetti" L T Click to edit Master title style! !$ 0 0L " L RClick to edit Master text styles Second level Third level Fourth level Fifth level!     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S  6 ?w `P  w P*    6Zw `  w R*  H  0޽h ? ̙33! 00(  x  c $ 4P   x  c $P 48 `    H  0޽h ? ̙33  PX$(  Xr X S 0   r X S P0  H X 0޽h ? &L333333x&-LYMMM  $(  r  S n0  n r  S @n0 n H  0޽h ? fDW&cC3  ,0(  ,x , c $|n0  n x , c $ n0 n H , 0޽h ? fDW&cC3   0(  x  c $V0   x  c $`W0  H  0޽h ? fDW&cC3  ($(  (r ( S Dn0  n r ( S n0 n H ( 0޽h ? fDW&cC3 ! 0(  x  c $(n0  n x  c $n0P n H  0޽h ? fDW&cC3   0(   x  c $hNw0  w x  c $Nw0 w H  0޽h ? fDW&cC3  08$(  8r 8 S 0   r 8 S |0  H 8 0޽h ? &L333333x&-LYMMM0 @<&(  <X < C     < S XQn @   (Anthony D. Joseph: Title: Many security challenges What does misleading data mean? DoS becomes DDos attacks Some scalable defenses: - Add computational complexity (cryptographic actions  node id generation , msg signing) - Byzantine - Redundancy is a double edge sword, could be usurped to cause more problems - Instead of access control, maybe chained authenticators  you can use the network if trusted  but this is the problem the M$ guy gave up on. @ 2,_nH < 0޽h ? ̙33L0   @(  @X @ C     @ S 8)n @   *Anthony D. Joseph: Title: Introspective tuning for reality What does incorporate ext knowledge mean? Network latency discontinuities are a problem - Several order of magnitude jump from LAN to WAN - General solution: Brocade super nodes, Short-circuit path to minimize wide-area hops via 2nd overlay Non-uniformity in & - PDA & - Segregate super nodes, infrastructure routers, pure clients, storage, & X 2pH @ 0޽h ? ̙33`0  D(  DX D C     D S n @  ___PPT9tl :Anthony D. Joseph: Extending the Scope of P2P Overlay Networks - Most current research is focused on file storage and retrieval But, they have much broader utility - routing - data dissem. - multimedia IM/comm - collab apps New slide: some deployment challenges - Can stability be enhanced by  creative placement of stable nodes - User-driven (barter incentives) - Corporate (ISP, OS storage provider, etc) - Respecting SLAs - Current approaches turn stub networks into transit networks -- (@home node/cable segment becomes major router!) b 2$ -2< -2& -2D -2N -2 -2> -25 -2n$<&D  N  >5PuH D 0޽h ? ̙330 H:(  HX H C     H S  @   <Anthony D. Joseph: Overlay CONSTRUCTION and maintenance under instability - Without care, the worst case is & . 2nd bullet: Proactive overlay link construction and maintenance - Integrate OPTIMAL routes at node insertion time - Estimate global knowledge w/ distrib & - RT heuristics are too late (require too much time  O(RTT)?) bN 2_DH H 0޽h ? ̙330 LT(  LX L C    n L S Ȳn @  n VAnthony D. Joseph: Loss from routing reconfiguration delays of minutes or more: BGP convergence time of 3 to 15 minutes Stress model is now semi-connected versus semi-disconnected (ie, bigger islands of connectivity @ 2"H L 0޽h ? ̙33l0 ,$P(  PX P C    $ P S  @   bAnthony D. Joseph: First bullet: Pushing the bounds of infrastructure scalability - Logarithmic bounds are not enough! - Have to deal with the worst-possible cases: massive & @ 2H P 0޽h ? ̙33?0 T(  TX T C     T S w @   ?Anthony D. Joseph: Need a Why Overlay Networks bullet/slide? -6@ 2-H T 0޽h ? ̙33j 0 *"`\(  \X \ C    w" \ S $ w @  w |More than IP-level best-effort functionality, faster fault recovery, intelligent service placement, mobility, multicast, & Millions (billions?) of IP-capable thin clients becoming available$ 2H \ 0޽h ? ̙33r\ |:0>@RDfHzLNvJVF!/.PR|X]8f*k6nqNBs cwxOh+'0,R hp $ D P \hpLarge-scale Dynamic Overlayst Ben Y. ZhaoOC:\Program Files\Microsoft Office\Templates\Presentation Designs\Ricepaper.pot Ben Y. 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ZhaoBen Y. Zhao  !"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwyz{|}~Root EntrydO)PicturesF#Current UserSummaryInformation(N\RPowerPoint Document(wDocumentSummaryInformation8x