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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”
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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
Global Internet 2008
FIND PI Meeting, April 2009
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
Global Internet 2008
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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?
FIND PI Meeting, April 2009
Intensity of Overlap
Link Capacity 1.5 GbpsUtilization = 10%
Link Capacity 0.3 GbpsUtilization = 50%
Flow1 50 mbps
Flow2 100 mbps
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
Simulation Results:Dynamic demand
Mean fraction 16.4 %
EXODUS – 372 g2g paths
IEEE IWQoS 2008
FIND PI Meeting, April 2009
Network Analysis: Robustness against failures
Mean fraction 27%
EXODUS – 372 g2g paths
IEEE IWQoS 2008
FIND PI Meeting, April 2009
Simulation Results:Effect of Simplified Pricing
ABOVENET – histogram of 7 days revenue
Node 5Node 1
pt-anywhere pricing
g2g pricing
simplified g2g pricing
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
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
FIND PI Meeting, April 2009
Thank you!
THE END