Is IP going to take over the world (of communications)? Pablo Molinero-Fernandez Stanford University Nick McKeown Stanford University Hui Zhang Turin Networks, Carnegie Mellon University Text from Alan Mislove, Ansley Post

Background The Internet is one of the most successful communications platforms because of two characteristics Reachability Heterogeneity Almost all Internet traffic is over Internet Protocol (IP) First created in 1970, called Mark I

Background (cont) Internet’s success has lead to the assumption that it will become the only communication platform Phone Networks would be replaced with voice-over-IP systems; Skype (100 million users in just 3 years) Vonage (100k users in just 3 years), Movies and Television will be distributed using Internet YouTube, VideoFurnace, Google Videos Similarly, it has also lead to the assumption that packet- switching (IP) routers will become the only switching device.

Motivation Despite its strengths, IP is not necessarily the best solution Goal of our paper: Counter the assumption that IP will “take over the world (of communications)” Comparing packet switching to other switching devices Shatter false assumptions that lead to this belief

IP Misbeliefs Widely held assumptions that will be questioned Current dominance of IP over other communications IP’s efficiency IP’s robustness IP’s simplicity Real-time applications using IP

Dominance of IP It is falsely believed that IP currently dominates global communication ISP’s have revenues of $13B Compared to other communications’ revenues totaling $344B Internet only reaches 59% of US phone 94% & TV 98% IP market is smaller in the data & telephony infrastructure IP routers market size: $4.1B circuit-based router market size: $32.5B

Efficiency of IP IP makes efficient use of “scarce” bandwidth But is it really scarce? Average Internet link utilization is 3%-20% Ethernet networks utilization is much lower at ~1% Long-distance phone line utilization is 33% Network’s over provision allows for a low packet delay

Efficiency of IP (cont) Why? (Over Provision) 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, traffic loops, etc… Much easier to keep utilization low

Efficiency of IP (cont) In practice, user experiences the same delay in packet- switched or circuit-switched network Average user’s work (65%) is request-response File sharing For most types of workloads, circuit-switching provides same user response time

Robustness of IP Internet was designed to withstand catastrophic event. 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

Simplicity of IP 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

Simplicity of IP (cont.) IP routers have about 8 million Circuit-switched routers have 3 million lines of code 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 9% - 50% the price IP routers do not lend themselves to implementing optics Circuit switching is compatible with optical technology

Real-Time Support in IP Widely held assumption that IP will support real-time applications This assumption relies on over provisioning of the network Or Quality-of-service in the network that has yet to be implemented Even after 10 years of research, no infrastructure has been created (using IP routers) to replace circuit switching.

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

Conclusion IP does some things well, 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

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 everyday, […] and for which telephony already provides a better solution with a marginal cost of almost zero”