find pi meeting, april 2009 1 contract-switching: value flows in inter-domain routing murat yuksel...

FIND PI Meeting, April 2009

1

Contract-Switching: Value Flows in Inter-Domain Routing

Murat YukselUniversity of Nevada – Reno

Reno, NV

Aparna Gupta, Koushik Kar, Shiv Kalyanaraman Rensselaer Polytechnic Institute

Troy, NY

Project Websitehttp://www.cse.unr.edu/~yuksem/contract-switching.htm

Or google “Contract Switching”


2

Implied ChallengesMotivation

Current architectural problems: Users cannot express

value choices at sufficient granularity – only at access level

Providers do not have economic knobs to manage risks involved in

QoS investments inter-ISP relationships

flexibility in time:

forward/option pricing

flexibility in space:

user-defined inter-domain

routes

capability to provide e2e

higher quality services

money-back guarantees,

risk/cost sharing


3

Inter-domain struggles…

When crossing domains, all bets are off..

End-to-end QoS or reliability requires assurance of single-domain performance, i.e., “contract”s efficient concatenation of single-domain contracts

Inter-domain routing needs to be aware of economic semantics

contract routing + risk management

We address translation of these struggles to architectural problems


4Contract-switching: A paradigm shift…

Circuit-switching

Packet-switching

Contract-switching

ISPA

ISPC

ISPB

e2e circuits

ISPA

ISPC

ISPB routable

datagrams

ISPA

ISPC

ISPB contracts

overlaid on routable datagrams


5

Contract Link

An ISP is abstracted as a set of “contract links”

Contract link: an advertisable contract between peering/edge

points with flexibility of

advertising different prices for edge-to-edge (g2g) intra-domain paths

capability of managing value flows at a finer granularity

than point-to-anywhere deals


6

How to achieve e2e QoS? Contract Routing – spatial composition of

e2e contracts Compose e2e inter-domain “contract paths” over

available contract links satisfying the QoS requirements

Calculate the contract paths by shortest-path algos with metrics customized w.r.t. contract QoS metrics

Two ways: link-state contract routing at macro time-scales path-vector contract routing at micro time-scales

Monitor and verify that each ISP involved in an e2e contract path is doing the job

Punish the ISPs not doing their job, e.g. as a money-back guarantee to the others involved in the e2e contract path


7Link-State Contract Routing: Macro-level, proactive

User X

2

3

5

ISPA

ISPC

ISPB

1

OwnerISP

Link

QoS Term

OfferedAfter

Price($/term)

A 1-2 10Mb/s 2hrs 1hr $10

A 1-3 40Mb/s 5hrs 15mins $80

B 2-4 100Mb/s

3hrs 2hrs $110

C 3-5 20Mb/s 1hr 30mins $8

C 4-5 60Mb/s 1day 2hrs $250

4

Most cost-efficient route

Max QoS route

Global Internet 2008


8

Path-Vector Contract Routing: Micro-level, on-demand, reactive

User initiates… User X wants to know if it can

reach 5 with 10-30Mb/s for 15-45mins in a $10 budget

User X

2

3

5

ISP A

ISPC

ISPB

1 4

[5, A-B, 1-2-4, 15-20Mb/s, 20-30mins, $4]

[5, A, 1-2, 15-30Mb/s, 15-30mins, $8]

[5, 10-30Mb/s, 15-45mins, $10]

[5, A, 1-3, 5-10Mb/s, 15-20mins, $7]

Paths to 5 are found and ISP C sends replies to the user with two specific

contract-path-vectors.

path request path request

path request

[A-B-C, 1-2-4-5, 20Mb/s, 30mins]

[A-C, 1-3-5, 10Mb/s, 15mins]

Paths to 5 are found and ISP C sends replies to the user with two specific

contract-path-vectors.

replyreply

reply



9

Path-Vector Contract Routing: Micro-level, on-demand, reactive

Provider initiates…

ISP C wants to advertise availability of a short-term contract link

User X

2

3

5

ISPA

ISPC

ISPB

1 4

[C, 5-4, 30Mb/s,

45mins, $9]

[C-B, 5-4-2, 20Mb/s, 45mins, $6+$5]

[C-B-A, 5-4-2-1, 20Mb/s, 30mins, $7.3+$3]

[C, 5-3, 10Mb/s, 30mins, $5]

[C-A, 5-3-1, 5Mb/s, 15mins, $1.25+$1.2]

pathannouncement

path

announcement pathannouncement



10Temporal Extensions of Single-domain QoS Contracts

Bailout Forwards: on advertisable spot contracts with flexibility of

advertising different forward prices for g2g intra-domain paths

Forwards with provision for bailout conditioned on network status

Time


Bailout Forward Contract

Multiple g2g Contracts

• Exposed to the additional effects of other traffic flows as a result of overlapping links with other g2g overlay paths

• How do we model this interaction?


Intensity of Overlap

Link Capacity 1.5 GbpsUtilization = 10%

Link Capacity 0.3 GbpsUtilization = 50%

Flow1 50 mbps

Flow2 100 mbps


BFC Performance

Can an ISP survive by applying BFC approach? How frequent does BFC bailout?

BFC Robustness against increasing demand? (demand) decreasing available bandwidth? (supply) major link failures?

How efficient is BFC pricing? Revenue Losses


Simulation Results: Dynamic Demand

PathForward Prices

E[ST] Probability

{ST>F} Probability{AT<Th}

1 0.20609 0.20305 0.502 0.092 0.27162 0.24982 0.449 0.0653 0.21293 0.21213 0.486 0.0794 0.25039 0.24825 0.477 0.0945 0.22177 0.21211 0.465 0.093

Threshold = 15th percentile

Results for five sample g2g contracts

Financial guess – Forward

breakdown prob

Technical guess - Bailout

probability

IEEE IWQoS 2008


Simulation Results:Dynamic demand

Mean fraction 16.4 %

EXODUS – 372 g2g paths

IEEE IWQoS 2008


Network Analysis: Robustness against failures

Mean fraction 27%

EXODUS – 372 g2g paths

IEEE IWQoS 2008


Simulation Results:Effect of Simplified Pricing

ABOVENET – histogram of 7 days revenue

Node 5Node 1

pt-anywhere pricing

g2g pricing

simplified g2g pricing


Simulation Results:Effect of Forward Pricing

ABOVENET – 40% of available capacity is contracted as “forward”

Node 1

pt-anywhere pricing

simplified g2g pricing

simplified forward g2g pricing


19

Future Work and Questions

Protocol implementation and simulation of CR

Balance between LSCR and PVCR

ISP collaboration and competition pricing the inter-domain risk game theoretic analysis contract verification common punishment and rewarding laws

Goal: more economics in inter-domain routing


Thank you!

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