is ip going to take over the world (of communications)? pablo molinero-fernandez, nick mckeown...

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


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


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


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


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%


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


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


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


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


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


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


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


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 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


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”

is ip going to take over the world (of communications)? pablo molinero-fernandez, nick mckeown...

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