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Seminar on “Clean Slate Design for the Internet”

Nick McKeownnickm@stanford.edu

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High level

“Given what we know today, if we were to start over with a Clean Slate, how would we design a global communications network?”

“Ideally, how will the network look in 15-20 years, and how will we get there from here?”

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What’s wrong with the Internet…?

Why is the research and business community not already solving it?

What are other groups doing?

What we plan to do at Stanford

An example of “Clean Slate” design

Prelims

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Original Architecture

A dumb connectionless packet-forwarding packet-switched infrastructure, with high-level functionality at the edge

Single, simple lowest-common denominator data delivery service (IP), with reliable stream service built on top

Fixed-size numerical addresses with {network, host} hierarchy; one per physical network interface

Later Separation of IP and TCP (including congestion control

using packet loss as congestion signal)

Subnetting, autonomous systems (EGPs and IGPs), DNS, CIDR

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What is needed

Wouldn’t we like a network that we can trust to be always there, always on, easy to use, universally accessible, secure, and economically viable. 

David Cheriton’s example: If the FAA carried all of its traffic over the public Internet, you'd be nuts to fly.

Some obvious desirable characteristics Robustness and Availability Security Naming and Addressing: accountability vs anonymity Predictability Mobility Economic Viability

What else?

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What’s wrong with the Internet…?

Why is the research and business community not already solving it?

What are other groups doing?

What we plan to do at Stanford

An example of “Clean Slate” design

Prelims

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What’s wrong with the Internet…?

Why is the research and business community not already solving it?

What are other groups doing?

What we plan to do at Stanford

An example of “Clean Slate” design

Prelims

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What are others doing?

Background

Incrementalism and “victim of success” of Internet

New era of more radical and fundamental thinking about the future of networks and communications

New-arch (MIT)

100x100 (CMU)

Geni (NSF/Gov)

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New-arch (2000)

Requirements for new network

Mobility: Highly dynamic and efficient

Policy-driven auto-configuration

Highly time-variable resources

Allocation of capacity

http://www.isi.edu/newarch/

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100x100 (CMU/Stanford/Rice)

NSF Large ITR (2003-2008)

Questions:

Can structure be used to make networks more robust, predictable and manageable?

What economic principles drive the operation of access and backbone networks?

What security primitives must be built into the network?

Can/should network and protocol architectures be designed to take advantage of long-term technology trends?

http://100x100network.org/

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NSF Geni Initiative (2005)

CISE major effort, seeking congressional funding of approx $300M starting 2008

Two parts: Research program; Global experimental facility to explore new architectures

Areas of interest: Creating new core functionality, including naming,

addressing, identity, management. Developing enhanced capabilities: building security intot he

architecture; design for high availability; privacy/accountability; design for regional differences and local values

Deploying and validating new architectures Building higher-level service abstractions Building new services and applications Developing new network architecture theories

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What’s wrong with the Internet…?

Why is the research and business community not already solving it?

What are other groups doing?

What we plan to do at Stanford

An example of “Clean Slate” design

Prelims

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What’s wrong with the Internet…?

Why is the research and business community not already solving it?

What are other groups doing?

What we plan to do at Stanford

An example of “Clean Slate” design

Prelims

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What we plan to do at Stanford

Weekly Seminar in Fall and Winter

Fall: Talk by professor followed by discussion

Goals

To get thinking about the problem

To learn from each other

To identify some collaborative research projects

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What’s wrong with the Internet…?

Why is the research and business community not already solving it?

What are other groups doing?

What we plan to do at Stanford

An example of “Clean Slate” design

How to design backbone networks from a clean slate?

Prelims

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Backbone Networks: Emerging Structure

10-50 routing centers interconnected by long-haul optical links

Increasingly rich topology for robustness and load-balancing

Typical utilization < 25%, because

Uncertainty of traffic matrix network is designed for

Headroom for future growth

Headroom to carry traffic when links and routers fail

Minimize congestion and delay variation

Efficiency sacrificed for robustness and low queueing delay

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How flexible are networks today?

Abilene Verio

AT&T Sprint

25% Over Prov: 0.025%50% Over Prov: 0.66%

What fraction of allowable traffic matrices can they support?

25% Over Prov: 0.0004%50% Over Prov: 1.15%

25% Over Prov: 0.0006%50% Over Prov: 0.15%

25% Over Prov: 0.0003% 50% Over Prov: 0.06%

Verio, AT&T and Sprint topologies are from RocketFuel

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Desired Characteristics

RobustRecovers quickly; continues to operate under failure

Flexible Will support broad class of applications, new customers, and traffic patterns

PredictableCan predict how it will perform, with and without failures

EfficientDoes not sacrifice cost for robustness

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Backbone Design

Assume underlying reliable mesh of physical circuits

1. Dynamic circuit switching over underlying mesh, or

2. Load-balanced logical network. Describing today

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Approach

Assume we know/estimate traffic entering and leaving each Regional Network

Requires only local knowledge of users and market estimates

Use Valiant Load Balancing (VLB) over whole network

Enables support of all traffic matrices

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Valiant Load-Balancing

1 2

3N

… 4

r1

2r1r2 /rN r2

r3

r4

rN

Capacity provisioned over existing robust mesh of physical circuits

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A Predictable Backbone Network

Performance: 100% throughput for any valid traffic matrix. Only need to know aggregate node traffic. Under low load, no need to spread traffic.

Robustness Upon failure, spread over working paths

Small cost to recover from k failures: Provision approx 2rirj/r(N-k) Simple routing algorithm

Efficient VLB is lowest cost method to support all traffic matrices Similar cost, while supporting significantly more traffic matrices.

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How expensive would VLB be?

Abilene Verio

AT&T Sprint

25% Over Prov: 0.026% Cost: 0.8750% Over Prov: 0.66% Cost: 1.04

Cost normalized to VLB routing. Cost of switching = cost of transmission for 370miles

25% Over Prov: 0.0003% Cost: 0.9950% Over Prov: 1.08% Cost: 1.19

25% Over Prov: 0.0004% Cost: 0.9450% Over Prov: 0.14% Cost: 1.12

25% Over Prov: 0.0002% Cost: 0.86 50% Over Prov: 0.04% Cost: 1.04

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Open questions

Worst case propagation delay doubled

Low variance in delay

There are “express paths”

(How) are multiple VLB networks connected, and how does performance change?

Economics and policy: how do operators compete?