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UMass DieselNet: A Disruption-Tolerant Network Testbed

UMass DieselNet: A Disruption-Tolerant Network Testbed. John Burgess Department of Computer Science UMass Amherst. DieselNet. Vehicular DTN deployed in Amherst and surrounding county Now includes 40 buses

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UMass DieselNet: A Disruption-Tolerant Network Testbed

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  1. UMass DieselNet:A Disruption-Tolerant Network Testbed John Burgess Department of Computer Science UMass Amherst

  2. DieselNet Vehicular DTN deployed in Amherst and surrounding county Now includes 40 buses Each bus: Linux “brick” computer; USB 802.11b adapter; 802.11b AP; GPS receiver, 40GB hard drive Buses transfer data as they pass by each other and via available hot spots.

  3. The Openbrick • Small form factor • Plentiful I/O • Binary availability for x86 • 60w peak power draw • Low heat dissipation

  4. DieselNet Software Considerations • Autonomous operation and “shutdown” • Maximal failure tolerance • No remote administrator login or local terminal • Physical inaccessibility during operation (6am - 1am) • Nodes versus support staff • Handle network interface configurations • Support IP programs • Handle bundle routing • Support DTN programs

  5. Init and Restore • Linux and initial software stored on 1st partition • All DTN software, logs, bundles, cached web content, etc. stored on 2nd partition • Restore checks for the presence of critical files • If any critical files are inaccessible • Clear extended partition • Restore initial software package from system disk • Otherwise, Init starts system software 1GB hdc1 39GB hdc5

  6. Autoupdate • Install new software • Check for new gzip files on prisms web site • Verify prisms signature • Install update atomically • Sync system clock with server • Report current location • Report log entries • Connection events • Program error messages • Upload files • Bzip file, MIME encode it, and upload via HTTP request header

  7. LiveIP • Manage network interfaces • 802.11b • Scan for ssid broadcasts on all channels • Connect to other buses • Hash foreign bus MAC address to determine subnet • Connect to access points • DHCP • Ping foreign device to decide when to resume scanning • Reload 802.11 driver to clear malfunctions • Additional interfaces to be managed • 900mhz long-range radio (1km) • CDMA modem

  8. GPSupdate • Receive NMEA formatted information via RS232 • Compute speed, direction, etc. • Periodically log location • Provide location information to onboard programs

  9. DTNdaemon • Accept data and send bundles • via local TCP socket • Route bundles according to configured protocol • MaxProp • Deliver data to appropriate onboard programs • Programs connect via TCP socket • Programs register as appropriate destination application • Platform and IP network interface independent • Java implementation with no external dependencies • DTN2 2004 bundle format compatibility

  10. Software Components • Init and Restore • Perl and Python • Auto update • Python • Live IP • Java 1.4 • GPS update • Python • DTN daemon • Java 1.4 and linux-only Java 1.3

  11. Connection Events • Red dots indicate bus-to-bus transfers (1 month) • Measurement of real TCP throughput • Traces collected everyday

  12. Measurements Buses log their status via available access points (and update software). Transfer duration Inter-transfer opportunity time Bytes transferred

  13. Future Work • Deploy different DTN routing protocols • Develop useful disruption tolerant applications • Expand network to include other types of nodes

  14. Summary • DieselNet is a DTN Testbed deployed on public transportation busses • Network inaccessibility often corresponds to physical inaccessibility, making DTN administration difficult • DTN system administration must be accomplished in a disruption-tolerant manner • Current above-IP DTN solutions must handle configuration of IP, Link, and physical network • Future solutions running above the link layer will still need to configure the link and physical layer

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