Pastry Scalable_ decentralized object location and routing for large by yurtgc548

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									Is IP going to take over the
world (of communications)?

Pablo Molinero-Fernandez, Nick McKeown Stanford University

Hui Zhang   Turin Networks, Carnegie Mellon University




                  Alan Mislove, Ansley Post COMP 629 1.22.2004
Background
   The Internet is one of the most successful
    communications platforms
     Seen   exponential growth in the past decade

   Almost all Internet traffic is over Internet Protocol
    (IP)
     Designed   in 1970s through DARPA funding

   IP’s great success due to
     Reachability
     Heterogeneity


                                    Alan Mislove, Ansley Post COMP 629
                                    1.22.2004
Background (cont.)
   Success has lead to the assumption that IP will
    become the sole communication platform
     Voice-over-IP systems will replace phone network
     TV, Movies will be disseminated using Internet


   Related assumption is that packet-switching (IP)
    routers will become the only type of switching device




                                  Alan Mislove, Ansley Post COMP 629
                                  1.22.2004
Motivation
   IP is technically able to support all types of
    applications
     Request-reply  (web traffic)
     Real-time (telephony)


   Despite its strengths, not necessarily the best
    solution

   Goal: Question previous assumptions that IP will
    “take over the world (of communications)”
     Evaluate   what would happen if we started over
                                     Alan Mislove, Ansley Post COMP 629
                                     1.22.2004
IP Folklore
   There are many widely held assumptions (“sacred
    cows”) about IP that must be reevaluated
     The  current dominance of IP for communications
     The efficiency of IP
     The robustness of IP
     The simplicity of IP
     IP’s suitability for real-time applications




                                  Alan Mislove, Ansley Post COMP 629
                                  1.22.2004
IP Communications Dominance
   It is widely (and incorrectly) believed that IP already
    dominates global communication
     ISP markets
                have revenues of $13B
     Other communication markets total over $300B


   For data and telephony applications alone, IP
    routers total $4B, while circuit-based router total
    $32B

   Internet reaches 59% of US, phone 94%, TV 98%

                                   Alan Mislove, Ansley Post COMP 629
                                   1.22.2004
IP’s Efficiency
   IP makes efficient use of scarce bandwidth
     Very  good for wireless channels, satellite links, etc…
     But is bandwidth actually scarce?


   Average Internet link utilization is 3%-20%
     LAN usage is much lower, about 1%
     Long-distance phone utilization is 33%


   Networks are highly overprovisioned to provide a
    consistent user experience
     Low    packet delay is the goal
                                        Alan Mislove, Ansley Post COMP 629
                                        1.22.2004
IP’s Efficiency (cont.)
   Many reasons given for overprovisioning
     Internet  traffic is asymmetric and bursty
     Difficult to predict traffic growth on a link
     Economical to add large increments of capacity


   However, there are “less talked-about” reasons
     Under congestion, IP performs badly
     Control traffic transmitted in-band
     Results in black holes, loops, etc…


   Much easier to keep utilization low
                                  Alan Mislove, Ansley Post COMP 629
                                  1.22.2004
IP’s Efficiency (cont.)
   In practice, user experiences the same delay in
    packet-switched or circuit-switched network

   Average user’s work (65%) is request-response
     Web traffic
     File sharing


   For these types of workloads, circuit-switching
    provides same user response time


                                  Alan Mislove, Ansley Post COMP 629
                                  1.22.2004
IP’s Robustness
   Internet was designed to withstand catastrophic
    event, but
     Median Internet downtime is 471 minutes/year
     Median phone downtime is 5 minutes/year


   BGP convergence is slow (3-15 minutes)
     SONET/SDH    switches to a backup path in 50ms


   Nothing inherently unreliable about circuit-switching


                                  Alan Mislove, Ansley Post COMP 629
                                  1.22.2004
IP’s Simplicity
   Beginning principle is that complexity should be at
    the endpoints
     Increasingly,    IP routers have become sophisticated
           Multicast
           Quality of Service
           VPN


   Configuring IP routers can be very difficult
     Single  misconfigured IP router can cause instability
      for a large portion of the network


                                      Alan Mislove, Ansley Post COMP 629
                                      1.22.2004
IP’s Simplicity (cont.)
   Circuit-switched routers have 3 million lines of code
     IP routers   have about 8 million


   IP routers have 300 million gates, 1 CPU, 300 MB of
    buffer space
     Circuit   routers have 25% of the gates and no CPU

   Circuit-switched routers sell for 1/2 - 1/12 the price

   Circuit switching is compatible with optical
    technology
                                     Alan Mislove, Ansley Post COMP 629
                                     1.22.2004
IP’s Real-Time Support
   Widely held assumption that IP will support real-time
    applications
     This assumption relies on overprovisioning of the
      network
     Or quality-of-service in the network that has yet to be
      implemented




                                    Alan Mislove, Ansley Post COMP 629
                                    1.22.2004
What if we started over?
   Hybrid solution would be most appropriate
     Uses  packet switching at the edges
     Circuit-switching at the core and with applications with
      QoS demands
     Tightly integrate these two parts




                                    Alan Mislove, Ansley Post COMP 629
                                    1.22.2004
Conclusion
   IP does some things good, but not everything
     Good     for scarce-bandwidth situations
           Wireless, undersea cables, satellite links
     Inappropriate     for real-time applications
           Voice traffic, telephony


   If we redesigned the Internet, not all routers would
    be packet-switching
     Core  routers and real-time application data would be
      circuit-switched


                                         Alan Mislove, Ansley Post COMP 629
                                         1.22.2004
Questions?
   Mike O’Dell, former Senior VP, UUNet:
     “[to have a voice-over-IP network service one has to]
      create the most expensive data service to run an
      application for which people are willing to pay less
      money every day”




                                   Alan Mislove, Ansley Post COMP 629
                                   1.22.2004

								
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