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

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 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 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 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 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 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 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 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 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 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 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 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 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 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 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”