Distributed Monitoring of Mesh Networks

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Distributed Monitoring of Mesh Networks

• Elizabeth Belding-Royer
• Mobility Management and Networking (MOMENT) Lab
• Dept. of Computer Science
• University of California, Santa Barbara
• Joint work with Krishna Ramachandran and
• Kevin Almeroth

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Motivation Monitoring

• crucial for robust network operation
• benefits to network operators, system designers,
  researchers
• essential for evolving network technologies
• critical last piece in the product
  conception-design-development-improvement loop
• helps bridge the gap between the expected
  (simulations) and the unexpected (real-world)

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The Big Picture

• Deployment
• UCSB 25 node mesh network (NSF WHYNET project)
• Monitoring and Measurement (DAMON)
• UCSB mesh
• IETF meetings
• LocustWorld, IV deployments
• 11,000 AODV nodes in 50 countries
• Simulation models
• movement models
• traffic models
• AODV refinement

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The Big Picture

• Deployment
• UCSB 25 node mesh network (NSF WHYNET project)
• Monitoring and Measurement (DAMON)
• UCSB mesh
• IETF meetings
• LocustWorld, IV deployments
• 11,000 AODV nodes in 50 countries
• Simulation models
• movement models
• traffic models
• AODV refinement

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Outline

• DAMON Design and Architecture
• DAMON Implementation
• DAMON_at_IETF
• Conclusions

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Design Challenges

• Device mobility
• Resource constraints
• Fluctuating link quality
• Short-lived network connections

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Design Choices Pervasiveness of Monitoring
Solution

• Strategy of using a centralized network element
  fails
• no hierarchical structure to mobile networks
• mobility
• Monitoring mobile networks requires pervasive
  solution
• nodes participate in monitoring
• Amount of pervasiveness
• complete coverage strategy
• limited coverage strategy

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Design Choices Pervasiveness of Monitoring
Solution

• Strategy of using a centralized network element
  fails
• no hierarchical structure to mobile networks
• mobility
• Monitoring mobile networks requires pervasive
  solution
• nodes participate in monitoring
• Amount of pervasiveness
• complete coverage strategy
• limited coverage strategy

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Additional Design Choices

• Number of data sinks
• single sink?
• multiple sinks?
• Temporal property of monitoring information
• determined by monitoring requirements
• classifications
• time dependent information, e.g. topology
  information
• time independent information, e.g. packet logs
• require differentiated handling of data

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DAMON Distributed Architecture for MONitoring
mobile networks

• Overview
• agents within network collect information
• information stored at sinks
• sink auto-discovery
• resiliency to sink failures

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Architecture

• Agents within network send monitoring information
  to sinks
• Sinks emanate periodic beacons
• facilitates auto-discovery and resiliency to sink
  failures

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Sink Auto-discovery

• beacons contain agent instructions and hop count
• agents use hop count to choose primary sink

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Sink Auto-discovery

• Proximity-based association (hop count)
• simple, low overhead
• but, can lead to uneven distribution of agents to
  sinks
• Tradeoff between beaconing frequency and sink
  detection latency

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Monitoring Information

• Time dependent
• i.e., energy left on a device, neighbors
• typically small in size
• packaged into time dependent digests (TDDs)
• transmitted to sink frequently
• unreliable transmission

• Time independent
• i.e., packet logs, daily traffic statistics
• typically large in size
• broken into small-sized chunks called time
  independent digests (TIDs)
• reliable transmission

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Client Framework
Digest Classifier
File Server
Collector1
Collectorn

Beacon Listener
Packet Classifier
TDD Dispatcher
TID Dispatcher
Network

• Packet Classifier categorizes packets based on
  types, dispatches to appropriate packet handler
• Beacon Listener handles beacons
• TDD dispatcher handles received TDDs
• Collectors summarize routing table info or link
  quality estimates in TDDs and TIDs

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Client Framework
Digest Classifier
File Server
Collector1
Collectorn

Beacon Listener
Packet Classifier
TDD Dispatcher
TID Dispatcher
Network

• Digest Classifier delivers digests created by
  Collectors to appropriate module
• TDD Dispatcher for immediate transmission to sink
• File Server for TIDs for later delivery to sink
• TID Dispatcher periodically retrieves digests
  for transmission to sink

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DAMON Implementation

• Goals
• monitor ad hoc network behavior
• monitor AODV performance
• metrics of interest
• throughput
• traffic distribution
• control packet overhead
• mobility patterns
• Implementations for Linux and Microsoft Windows

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DAMON Information Collection

• AODV control packet summaries
• RREQ, RREP, RERR, Hello
• received packet counters
• UDP payload and timestamp
• Topology data
• routing table deltas
• AODV-NEIGHBOR TDDs sent every minute
• Data traffic statistics
• IP source and destination
• application protocol type
• packet size

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DAMON_at_IETF

• 58th IETF Meeting in Minneapolis, MN, November
  9-14, 2003
• Deployment goals
• validate DAMON design
• track IETF topology
• evaluate AODV performance
• observe traffic/mobility patterns
• AODV Implementation
• Linux, Windows (thanks Intel!)
• 130 downloads
• 20 simultaneous ad hoc network members

• Network configuration
• complete coverage strategy
• one gateway provided Internet connectivity to ad
  hoc network users
• one sink deployed to collect information
• ad hoc network co-located with 23 IETF APs
• nodes used tool called PUDL to avoid
  unidirectional links

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PUDL

• Periodic Uni-Directional Link detector
• periodic unicast probes between each neighbor
  pair
• sequence numbers used to measure reliability
• under some threshold (40), link filtered from
  AODV

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DAMON_at_IETF Network Topology
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Network Troubleshooting

• Connectivity problems with gateway reported
  during 1300-1530 IETF session on November 11th

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Lessons from Connectivity Information

• No correlation between reception of unicast and
  broadcast packets
• Routing protocols should select routes based on
  how reliably a path delivers unicast packets
• Relying on thresholds to avoid unidirectional
  links can eliminate links that are necessary for
  connectivity

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Traffic Distribution
Per Protocol, With Link Filtering
Per Protocol, Without Link Filtering
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AODV Traffic Distribution
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Conclusions

• Monitoring essential for robust network operation
• DAMON overcomes challenges associated with mobile
  network monitoring
• Future work more DAMON deployments and analysis
  tools

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• http//moment.cs.ucsb.edu/DAMON
• Funding provided by NSF and Intel Corporation