TELEFÓNICA I+D © 2007 Telefónica Investigación y Desarrollo, S.A. Unipersonal Good Things Come...

TELEFÓNICA I+D

© 2007 Telefónica Investigación y Desarrollo, S.A. Unipersonal

Good Things Come to Those Who (Can) Waitor how to handle delay tolerant traffic and make peace on the

Internet


Nikolaos Laoutaris (Telefonica Research)

based on joint work with Pablo Rodriguez (Telefonica Research)

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This paper is about shifting Delay Tolerant traffic away from the peak hour

ISPs dimension their networks based on peak hour load— peak hour load + QoS capital/operating cost

peak hour load can be broken down to:— Interactive part: web, email, YouTube, Skype— Delay Tolerant (DT) part:

– Existing DT: P2P high-def movie downloads, backups, OS/application updates– Future DT: Scientific datasets, e.g., from LHC@CERN

DT traffic on peak hour = inefficient use of network resources— Interactive traffic has a higher valuation for each unit of network resource— The network treats Interactive and DT traffic indiscriminately

We propose 2 ways to shift DT traffic away from the peak hour1. Source shifting through incentives for the end-users

2. In-network shifting through a storage-enabled network architecture

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Flat-rate pricing of residential broadband

Currently, lots of DT traffic overlaps with peak hours— P2P movie downloads— Users don’t bother pausing them— No incentive under flat-rate

pricing

Ideally:— DT downloads would pause during

peek— The movie will be seen later anyway

3

start a3GByte

download

go to sleep

downloadcompletes

peek hour

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Existing solutions

1. Congestion-based pricing solves the problem— But we know that users don’t like complicated pricing

2. Throttle all P2P— But not all P2P is delay tolerant— Requires expensive gear— Publicity disasters

3. Use capped “day-time” volume — Requires prediction of traffic needs— Assumes stationary behaviour BUT

– One day you work from home– Then next you fool around with P2P

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Our proposal: A flat-rate-compatible incentive scheme

Flat monthly charge

Ability to choose between 2 access modes on a daily basis — constant : fixed maximum data rate U during the 24 hours of the day

— reward : Un during P peak-hours and Ur during the remaining 24-P hours

The incentive max daily download volume— If your interactive traffic can live with Un during P and you care about P2P

downloads — Choose reward and you’ll have a much larger daily aggregate download volume

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Un

Ur

U

rate

time-of-day

P

flat-ratecompatible

nonintrusive

no per appscheduling

efficient use of network

adaptive(power of 2 choices)

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Making the time-shift of DT traffic opaque to the end-users

The previous incentive scheme requires some amount of user involvement

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OS bandwidth

cap at Un

What is we don’t want to involve the users?

Then network has to perform the time shifting of DT traffic

This requires having storage inside the network

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Storage-enabled network architecture

Large amounts of in-network storage— IPO’s at access ISPs— TSN’s at transit ISPs

How it works?— Users push data at full rate to

their local IPO— IPO’s and TSNs take over SnF

Two applications:A. Endogenous end-user DT data

– High res images/videos– backups

B. Exogenous DT data– CERN LHC data

Two pricing models:1. flat-rate

2. 95-percentile

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Sending pictures to family and friends (and fooling throttling)

A1: Minimize T((v,u),B,{X})— time required to send B GB of

photos

— from v to u

— flat-rate subject to time of day-based throttling {X}

E2E: low throughput due tothrottling

complementarities

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time-of-day

U

available

rate

ε v u

w

the general case is more interesting…

Xvw Xwu

XwuXvw

E2E

SnF

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Delay Tolerant Bulk data Is there an alternative to dedicated grids and

B2: Minimize Cost((v,u),B,T,{X})— $ paid in transit for B TB of

scientific data

— from v to u

— with max delay T

— 95-percentile with background load {X}

E2E: high cost — CBR pushes the background up by

B/T

— Source scheduling can also fail due to non-coinciding load valleys

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?

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Scheduling across 2 paid links

Things that affect the scheduling

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load ISP(v) → TR load TR → ISP(u)

C(q)

qbandwidth price ISP(v) → TR

C(q)

qbandwidth price TR → ISP(u)

Data: B

Delay Tolerance: T

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Crossing the Atlantic from LAT to EU

B=100

T=2

B=250

T=2

B=250

T=3

E2ELAT 53 130 46

EU 8 14 9

Total 61 144 55

SnFLAT 0 0 0

EU 0 7 0

Total 0 7 0

Amount that the CDN has to pay ISP(LAT) and ISP(EU) (x $1000)

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Conclusions DT @ peak hour = (economic) fat

— in a highly competitive ISP landscape less room for fat in our pipes

flat-rate compatible incentive schemes— simple way to remove DT traffic from peak hours

— + no change in the network

— - requires user attention– How capable are we in terms of ability for “Delayed Gratification”?

SnF + storage can outperform E2E— in performance for handling endogenous DTB (flat-rate pricing)

— in cost for handling exogenous DTB (95-percentile pricing)

Therefore it can— facilitate new applications (beat sneakernets?, interconnect datacenters)

— solve existing problems (ISP vs P2P tension)

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More info at: http://research.tid.es/nikos/

TELEFÓNICA I+D © 2007 Telefónica Investigación y Desarrollo, S.A. Unipersonal Good Things Come...

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