1. 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

2. 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)

3. 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

4. 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

5. Outline DAMON Design and Architecture DAMON Implementation DAMON@IETF Conclusions

6. Design Challenges Device mobility Resource constraints Fluctuating link quality Short-lived network connections

7. 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 Pervasiveness Network State Pervasiveness tradeoffs

8. 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 Pervasiveness Analysis Effort Pervasiveness tradeoffs

9. 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

10. DAMON: Distributed Architecture for MONitoring mobile networks Overview  agents within network collect information  information stored at sinks  sink auto-discovery  resiliency to sink failures

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

12. Sink Auto-discovery beacons contain agent instructions and hop count agents use hop count to choose primary sink

13. 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

14. 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

15. Client Framework 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 Packet Classifier Collector 1 Collector n Beacon Listener TDD DispatcherTID Dispatcher File Server Digest Classifier … Network

16. Client Framework 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 Packet Classifier Collector 1 Collector n Beacon Listener TDD DispatcherTID Dispatcher File Server Digest Classifier … Network

17. 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

18. 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

19. DAMON@IETF 58 th 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

20. 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

21. DAMON@IETF: Network Topology

22. Network Troubleshooting Connectivity problems with gateway reported during 13:00-15:30 IETF session on November 11th Node ID% Broadcast Hello % Unicast Probes 191.874.1 276.2612.69 392.0636 474.7342.18 569.2354.1 695.4211.4 797.856.66

23. Lessons from Connectivity Information 1. No correlation between reception of unicast and broadcast packets 2. Routing protocols should select routes based on how reliably a path delivers unicast packets 3. Relying on thresholds to avoid unidirectional links can eliminate links that are necessary for connectivity

24. Traffic Distribution Per Protocol, With Link FilteringPer Protocol, Without Link Filtering

25. AODV Traffic Distribution

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

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