Transcript Goyal

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
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The Internet is one of the most successful
communications platforms because of two characteristics
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Reachability
Heterogeneity
Almost all Internet traffic is over Internet Protocol (IP)
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First created in 1970, called Mark I
Background (cont)
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Internet’s success has lead to the assumption that it will
become the only communication platform
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Phone Networks would be replaced with voice-over-IP
systems;
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Skype (100 million users in just 3 years)
Vonage (100k users in just 3 years),
Movies and Television will be distributed using Internet
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YouTube, VideoFurnace, Google Videos
Similarly, it has also lead to the assumption that packetswitching (IP) routers will become the only switching
device.
Motivation
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Despite its strengths, IP is not necessarily the best
solution
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Goal of our paper:
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Counter the assumption that IP will “take over the world (of
communications)”
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Comparing packet switching to other switching devices
Shatter false assumptions that lead to this belief
IP Misbeliefs
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Widely held assumptions that will be questioned
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Current dominance of IP over other communications
IP’s efficiency
IP’s robustness
IP’s simplicity
Real-time applications using IP
Dominance of IP
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It is falsely believed that IP currently dominates global
communication
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ISP’s have revenues of $13B
Compared to other communications’ revenues totaling $344B
Internet only reaches 59% of US
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phone 94% & TV 98%
IP market is smaller in the data & telephony infrastructure
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IP routers market size: $4.1B
circuit-based router market size: $32.5B
Efficiency of IP
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IP makes efficient use of “scarce” bandwidth
But is it really scarce?
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Average Internet link utilization is 3%-20%
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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)
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Why? (Over Provision)
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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
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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)
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In practice, user experiences the same delay in packetswitched or circuit-switched network
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Average user’s work (65%) is request-response
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File sharing
For most types of workloads, circuit-switching provides
same user response time
Robustness of IP
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Internet was designed to withstand catastrophic event.
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Median Internet downtime is 471 minutes/year
Median phone downtime is 5 minutes/year
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BGP convergence is slow (3-15 minutes)
SONET/SDH switches to a backup path in 50ms
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Nothing inherently unreliable about circuit-switching
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Simplicity of IP
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Beginning principle is that complexity should be at the
endpoints
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Increasingly, IP routers have become sophisticated
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Multicast
Quality of Service
VPN
Configuring IP routers can be very difficult
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Single misconfigured IP router can cause instability for a
large portion of the network
Simplicity of IP (cont.)
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IP routers have about 8 million
Circuit-switched routers have 3 million lines of code
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IP routers have 300 million gates, 1 CPU, 300 MB of
buffer space
Circuit routers have 25% of the gates and no CPU
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Circuit-switched routers sell for 9% - 50% the price
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IP routers do not lend themselves to implementing optics
Circuit switching is compatible with optical technology
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Real-Time Support in IP
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Widely held assumption that IP will support real-time
applications
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This assumption relies on over provisioning of the
network
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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?
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Hybrid solution would be most appropriate
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Uses packet switching at the edges
Circuit-switching at the core and with applications with QoS
demands
Tightly integrate these two parts
Conclusion
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IP does some things well, but not everything
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Good for scarce-bandwidth situations
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Wireless, undersea cables, satellite links
Inappropriate for real-time applications
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Voice traffic, telephony
If we redesigned the Internet, not all routers would be
packet-switching
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Core routers and real-time application data would be circuitswitched
Questions?
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Mike O’Dell, former Senior VP, UUNet:
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“[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”