seminar on “clean slate design for the internet” nick mckeown nickm@stanford
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Seminar on “Clean Slate Design for the Internet” Nick McKeown [email protected]. 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?” - PowerPoint PPT PresentationTRANSCRIPT
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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?