Selective Flooding for Improved QualityofService Routing

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Selective Flooding for Improved
Quality-of-Service Routing
Mark Claypool and Gangadharan Kannan
Presented by Hariharan Kannan
Worcester Polytechnic Institute Worcester,
MA-01609, USA
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Selective Flooding for Improved
Quality-of-Service Routing

• Introduction
• Our Approach
• Implementation
• Evaluation
• Conclusions

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Introduction

• The Internet Connection-less, best effort,
  shared resources.
• QoS Routing Connection oriented, Guarantees on
  QoS.
• Feasible path search that satisfies QoS
  constraints of a connection.
• Network Topology Available Paths.
• Link State Information Available Bandwidth.
• Call Blocking Rate.

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Flooding, Source Routing

• Flooding. (K.J.Shin et.al., Sep 1995).
• No expensive LSAs, latest and hence, most
  accurate.
• High network bandwidth overhead.
• Source routing. ( Z.Zhang et.al., Sep 1997 ).
• Expensive LSAs.
• Stale information, hence high call blocking rate.
• High computing cost at switches per call.
• Goals.
• Low call blocking rate.
• Reduced network overhead.

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Our Approach Selective Flooding

• Store network topology as a graph at every
  source. (static).
• Multiple routes are computed and stored at the
  source.
• Bellman-Ford algorithm for computation of path.
  (Bellman, 1958, Ford et.al., 1962).
• On QoS request "selectively" flood control
  packets.
• Packets collect QoS info on the path.
• Destination/Source then chooses optimal/feasible
  path.
• Advantages.
• Reduced Network overhead On demand, selective.
• Reduced CBR Recent LS information.

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QoS Routing Illustration
Nodes
Links
Goal A-E Feasible Path search.
Illustration Topology
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QoS Routing Illustration Source Routing
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- Routing failure
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2
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QoS Routing Illustration Selective Flooding
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- Routing failure
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1
1
1
1
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2
X
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X
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Implementation

• Routesim. (A.Shaikh, Jun 1999) (A.Shaikh et.al.,
  Oct 1998).
• ( http//www.eecs.umich.edu/ashaikh/research/ ).
• Event driven simulator.
• Topology, Traffic generation, Routing algorithm,
  Link-state updates.
• Enhancing Routesim.
• Finding multiple paths.
• Selective flooding algorithm.

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Evaluation

• Selective Flooding vs. Source Routing
• Performance Measures
• Call Blocking Rate
• Network Overhead

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Conclusions

• Source Routing
• Call Blocking Rate vs. Network Overhead tradeoff.
• Selective Flooding
• Reduced call blocking rate, latest LSAs.
• Low switch computation overhead at marginal
  bandwidth overhead.
• Reduced call setup time.

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Future Work

• Hierarchical Routing for Scalability.
• Periodic link-state updates to provide fresh
  topology snapshots.
• Combine with source routing for volatile
  networks.
• Busy switches can block probing packets.

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Selective Flooding for Improved
Quality-of-Service Routing
Mark Claypool and Gangadharan Kannan
Presented by Hariharan Kannan
Worcester Polytechnic Institute Worcester,
MA-01609, USA