Sahara Overview

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Sahara Overview

• Jimmy, Lakshmi, Shelley, George

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Providing an end-to-end service with desirable
properties across distrusting service providers
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Model Space
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Key applications

• Roaming agreements (mobility, billing)
• ABC service (multi-access)
• Guaranteed bandwidth (QoS)
• Video conferencing/PSTN (gateway and transcoding
  agent selection)
• Portal service (composition)
• Content Distribution Network (CDN)

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Each model must export an API

• What is the API between service providers?
• How are APIs composed?
• How are APIs verified?

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Model 1a

• User relies on 1 provider to provide the service,
  different providers interact to provide the
  end-to-end service
• Routing/QoS/CDN

• How do we perform API propagation?
• Dist vector
• Link state
• Path vector (encapsulates trust, affinity)
• Path selection
• Instrumentation

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Model 1b

• User has a choice of serveral providers, each of
  which interacts with other providers
• Issues
• Choosing a single path
• Using multiple paths in parallel
• Fault detection/recovery/isolation

• We must define selection function f
• Dynamic recovery
• Instrumentation
• Alternative selection
• State transitioning

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Model 2

• An end-to-end service is provided through
  distributed algorithms that coordinate different
  service providers
• Model 2(i) can be thought of as an overlay.
  Example portal service
• In Model 2(ii), service composition occurs across
  multiple providers, with the primary service
  provider issuing control messages to the service
  instances

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Model 2(i)
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Model 2(i)

• Composition done using one provider
• Overlays without rerouting
• Verification of the individual functionality of
  entities
• Choose right service instance

• Examples
• Portal services
• Virgins value-added cell agreements
• Calling cards

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Model 2(ii)
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Model 2(ii)

• Data flows through service instances to sink
• Relationship between service instances cannot be
  verified by provider
• Dynamic rerouting must be used to choose new path
  from source to sink
• Instrumentation needed

• End-to-end connectivity
• QoS
• Video conferencing across heterogeneous access
  points

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Mechanisms/Enabling technology

• Jimmys work on congestion pricing
• Lakshmis verification work
• Yans measurement architecture
• Weidong/Matts auction based approach

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Model 1a
Model 1b
Sridhars ABC
Sharads overlay policy Matts g/w
selection Mukunds inter-domain mc Optical path
selection/connectivity Weidongs backup path work
Model 2
Mechanisms
Bhaskars service composition Morleys CDN Matts
gw selection Weidongs backup path work
Jimmys congestion pricing Lakshmis
verification Yans measurement arch Matt/Weidong
auction pricing