Staying focused on the big unsolved problemse.g. resource accountability

Bob BriscoeChief Researcher, BT GroupSep 2008

2

main problems with the current Internet

• interconnecting the information world with the physical world• publish-subscribe

• commercial viability & flexible comms industry structure• resource accountability• policy controls on overlay / inter-provider routing

• scaling for extreme dynamics• mobility, re-routes & failures, time-variable resources• high speed transfers, very short transfers

• availability & robustness to attack (not infoSec problem, nec.)• malware transmission & DDoS• reachability for the good guys through middlewalls

• management• failure tracking• policy-driven auto-config

3

research style– keeping focused

• all need a 'big science' approach• monumental but tedious research process• sustainable research teams• consensus on what each problem is separately

– based on rigorous analysis (engineering & economic)• a range of solutions proven much better than today for each problem

– rigorously analysed and strong economic cases for deployment• process for rough consensus on solution(s) to deploy

• computing / networking research not set up like that• the next sexy start-up idea from the lone PhD• research as marketing – crafted to hide weaknesses• little critical analysis of other work• emphasising novelty• de-emphasising commonality of analytical model• specialisation, not abstraction

"Hey, if you try this instead of that, simulations show it rocks and it's much better."

"We've invented this cool way to share resources in an ad hoc, cognitive, autonomic, meshed network of tetherless hospital beds, which is probably novel based on a survey of papers found on the first page of a Google search."

4

Flow-Rate Fairness: Dismantling a Religionexperience of trying to bring science into Internet research

2Mbps access each

80 users ofattended apps

20 users of unattended apps

usage type no. of users

activity factor

ave.simul flows /user

TCP bit rate/user

vol/day (16hr) /user

traffic intensity /user

attended 80 5% = 417kbps 150MB 21kbps

unattended 20 100% = 417kbps 3000MB 417kbps

x1 x20 x20

timeflowactivity

rate

10Mbps

5

two arbitrary approaches fightingbit-rate

time

'flow-rate equality' throttling heavy volume usagethe Internet way (TCP) operators (& users)

degree of freedom ‘flow rate equality’ ‘volume accounting’

multiple flows

activity factor

application control

congestion variation

• each arbitrarily cancels out the worst failings of the other• Internet looks like 'it works OK'• but arbitrary fighting leaves collateral damage

6

fairer is faster – incentivise end host behaviourbit-rate

time

light

heavy

light

heavy

light

heavy

'unfair' TCP sharingheavier usage takeshigher sharing weight

throttling heavy usage

• enabler: limit congestion, not volume• then end system congestion control will quickly evolve

• heavy usage will back away whenever light usage appears• so light usage can go much faster• hardly affecting completion times of heavy usage

• differentiated QoS as if in the network

lighter usage takeshigher sharing weight

7

limiting congestionwith flat fee pricing

• only throttles traffic when contribution to congestion elsewhere exceeds allowance

• otherwise free to go at any bit-rate

bulkcongestion

policer

congestion · bit-rate 0% · 2 Mb/s = 0.0kb/s

0.3% · 0.3Mb/s = 0.9kb/s0.1% · 6 Mb/s = 6.0kb/s

6.9kb/s

Internet

0.3%congestion

0%

0.1%

2 Mb/s0.3Mb/s6 Mb/s

Acceptable Use PolicyYour 'congestion volume' allowance: 1GB/month (= 3kb/s continuous)This only limits the traffic you can try to transfer above the maximum the Internet can take when it is congested.

Under typical conditions this will allow you to transfer about 70GB per day.

If you use software that seeks out uncongested times and routes, you will be able to transfer a lot more.

Your bit-rate is otherwise unlimited

8

mismatch of aspirationsexperience of trying to bring science into Internet research

• [y] Kelly's "Charging & Rate Control for Elastic Traffic": 1997• [z] "Dismantling a Religion" repeated the message: 2006• a rich and rigorous vein to tap for fixing the Internet

• resource accountability, simpler e2e QoS mechanism, e2e QoS for mobility, differentiated flow start-up, interconnection contracts, targeted liability for DDoS, traffic engineering and congestion routing, removing the need for deep packet inspection, removing need for rate limits into shared access networks (PON, cable, wireless)...

• context of all citations so far (paraphrasing)• "There are a number of approaches to fairness [w,x]; recently these have

been deeply challenged [y|z]; but we build on [x] which is generally used in the research community."

• Typical mailing list discussions "What's the problem? TCP works"

• ug

Staying focused on the big unsolved problemse.g. resource accountability

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