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ISPs as Nodes or Sets of Links?

Praveen K. MuthuswamyElectrical Computer and Systems Engineering

Rensselaer Polytechnic Institute

In collaboration withKoushik Kar, Aparna Gupta (RPI)

Hasan T. Karaoglu, Murat Yuksel (UNR)

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Motivation

Contract-Switching Architecture

Internet Traffic Engineering using Contract-switching

Numerical study and Benchmarking

Distributed TE Solution

Contributions and Future work

Outline

Attain high-efficiency inter-domain TE

Numerous methods for intra-domain TE

Inter-domain TE involves many factors ranging from

technology to economics and policy

Current Inter-domain TE techniques are constrained to

outbound traffic load balancing

Cooperative inter-domain traffic engineering among

neighboring ISPs is necessary

Motivation

ISP is abstracted as a single node or as a set of nodes

(in case of multiple ASes)

Node abstraction simplifies inter-domain routing

Loss of path selection and flexibility beyond shortest-

path routing in terms of AS hops.

Sufficient flexibility at the routing level is crucial for TE

Internet Routing Limitations

Link-state mechanisms to inter-domain routing

◦ K. Levchenko, G. M. Voelker, R. Paturi, and S. Savage. Xl: an efficient network

routing algorithm. In Proc. SIGCOMM, 2008.

Pathlet Routing abstracts ISP as virtual nodes

◦ Scott Shenker, P. Brighten Godfrey, Igor Ganichev, and Ion Stoica, Pathlet routing.

Proc. SIGCOMM, 2009.

Inter-AS source routing and GMPLS

◦ Xiaowei Yang, David Clark, and Arthur Berger, NIRA: A new inter-domain routing

architecture. IEEE/ACM Transactions on Networking, 15:775–788, 2007.

◦ E. Mannie. Generalized mpls architecture, RFC 3945

Related Work

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Contract-Switching Paradigm for Internet value flows and risk management, Yuksel et al. 2008

ISP is abstracted as a set of contract links

Contract link – Advertisable contract between edge nodes (peering points) of an ISP

Contract-Switching Paradigm

Network Coreaccessed onlyby contracts

Customers

EdgeRouter

EdgeRouter

EdgeRouter

EdgeRouter

EdgeRouter

EdgeRouter

Stations of the provider computing and advertising local prices for edge-to-

edge contracts.

30Mbps, 45 min, $9

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Each contract link follows a single, fixed intra-AS path End-to-end flows are optimally split along contract links Optimal inter-domain traffic engineering, but simple intra-

domain routing

Internet Traffic Engineering using CSP

Notations

- Bandwidth capacity of router-to-router link

- Physical links used to construct edge-to-edge link

- Total traffic at edge router for destination

- Flow on the contract or peering link

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Maximum Throughput Routing

Optimal TE formulation (1/2)

Capacity constraints

Flow-conservation constraints

Edge-to-edge flows

Throughput

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Minimum Delay Routing

Vxy(f) is a convex-cost with each router-to-router link. Consider M/M/1 delay cost.

Minimum Bandwidth Routing

Optimal TE formulation (2/2)

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Global Optimum (OPT) – Complete Internet topology

without abstractions (optimal inter and intra-domain

routing)

BGP framework – Least ISP hops for inter-domain and

OSPF/RIP for intra-domain

Frameworks for Benchmarking

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Random topology◦ Inter-domain and Intra-domain are random

BRITE topology◦ BRITE model for inter-domain◦ Rocketfuel Topologies (ABILENE and GEANT) for

intra-domain GTITM topology

◦ GTITM model for inter-domain◦ Rocketfuel Topologies (ABILENE and GEANT) for

intra-domain

Simulation Results

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Average throughput on 50 random topologies

Maximum Throughput

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Delay on Sample Random topology and Sample BRITE topology

Minimum Delay

Average total bandwidth on 50 BRITE topologies

Minimum Bandwidth

Derived using the gradient descent approach to penalized objective function

Traffic rate variables for each destination at each edge-link

Updating of traffic rates requires only “local” information Gradient projection method for AS j involves projection

on , the intra-domain capacity region Gradient projection method for e-edge links requires the

congestion along the link and local communication between the end nodes

Distributed TE solution

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Generate Internet topologies according to BRITE Size of each AS is 10 routers Obtain ratio of converged cost to optimum cost

Both average and maximum ratio is close to 1 Converged cost of the proposed TE solution is close to

the optimum

Numerical Study

Number of ASes

10 20 30

Average 1.0039 1.0057 1.0059

Maximum 1.0046 1.01 1.0093

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Average convergence time

Convergence if cost does not vary beyond 0.5% Convergence time seems to increase sub-linearly with

number of ASes, and number of destinations

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Contract link abstraction provides significant

improvement in routing performance over BGP

Close to the best achievable performance

Link abstraction is good for inter-domain traffic

engineering

Developed distributed TE solution based on gradient

descent and studied its performance numerically

Conclusion

Thank You !!Questions ?