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A Routing Protocol for Space Communication

A Routing Protocol for Space Communication. By: Nouman Bantan Advisor: Dr. Javed I. Khan Friday, February 16, 2007. Current Mobility. Space Mobility. Future Network. Mars Colonies. Mars Satellite Constellation. Earth-Sun LaGrange Point Satellite. Mercury Satellite Constellation.

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A Routing Protocol for Space Communication

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  1. A Routing Protocol for Space Communication By: Nouman Bantan Advisor: Dr. Javed I. Khan Friday, February 16, 2007

  2. Current Mobility

  3. Space Mobility

  4. Future Network Mars Colonies Mars Satellite Constellation Earth-Sun LaGrange Point Satellite Mercury Satellite Constellation MoonColony Phobos Colony EarthSatellite Constellations Moon Satellite Constellation Venus Satellite Constellation AsteroidBelt Satellites Earth-Sun LaGrange Point Satellite Space Station Comet Temple1 Colony Space Shuttle

  5. Table of Contents • Space Challenges • Previous Work • Our Space Routing Protocol • The Routing Algorithm • SOSPF Analysis • Dissertation Contribution

  6. Space Communication Challenges • Use of network state information • Where is the routing table created • Router Mobility • Predictable • Unpredictable • Convergence Stability Period Vs Convergence Period Convergence Period Stability Period Time All routing tables have converged A link is down All routing tables have converged

  7. Intermittent Path Long Delay More Space Communication Challenges (k, l) Up Traditional Path between k, l, and m Down (k, l) Up (l, m) Down Up (l, m) Up Down Down (k, l) + (l, m) (k, l) + (l, m) Up Up Down Down Time Time

  8. Table of Contents • Space challenges • Previous Work • The SOSPF routing protocol • The Routing Algorithm • SOSPF Analysis • Dissertation Contribution

  9. Previous Works: ASCoT • The NASA Autonomous Space Communications Technology (ASCoT) [Gnawali 05] • depends on underlying systems which provides • Navigation information • Local status • Ability to send and receive messages • Link trajectories, together with link attributes are disseminated throughout the network. • Then, each router can independently compute paths using a modified Dijkstra’s algorithm • No intermittent links support • Single point of failure

  10. Previous Work: STRF • Space Time Routing Framework (STRF) construct space-time routing tables [Merugu 04] • The next hop is selected from the current as well as the possible future neighbors. • Same size messages require the same propagation delay. • STRF supports intermittent links

  11. Table of Contents • Space challenges • Previous Work • The SOSPF routing protocol • The Routing Algorithm • SOSPF Analysis • Dissertation Contribution

  12. SOSPF Routing Protocol • Area Structure • Hello Protocol • Neighbor Structure • Predictable Model • Advertisements • Database Exchange Protocol • Flooding • Calculating Routing Table

  13. MC2 MC1 MC3 MC4 SOSPF Areas Architecture M2 • Satellite constellation are • Space colony area • Celestial object area M1 M6 M3 M4 M5 Mars Celestial Object Area Mars’s Satellite Constellation Area Celestial Object Area* M1,M2, M3, M4,M5, and M6 MC1, MC2, MC3, and MC4 M1 MC3 Mars’s Space Colony Area

  14. Area Border Routers: Satellite Constellation Border Router (SCBR) Earth-Moon Satellite Constellation 1’s Orbit (Area 1:3:1:1) Earth-Moon Satellite Constellation 2’s Orbit (Area 1:3:1:2) EM5 EM3 Space Shuttle 1 (Area 1:3:1:3) SP1 EM1 EM2 SCBR Members of Area 1:3:1 EM4 1:3:1 1:3:1:1 1:3:1:2 1:3:1:3

  15. Area Border Routers: Celestial Object Border Router (COBR) Earth Satellite Constellation 2’s Orbit (Area 1:3:2) Space Shuttle 1(Area 1:3:1:3) EM5 EM2 E5 SP1 EM3 EM1 E3 EM4 E2 E6 Members of Area 1:3 Members of Area 1:3:1 E1 E4 Earth-Moon’s Orbit (Area 1:3:1) Earth Satellite Constellation 3’s Orbit (Area 1:3:3) SCBR COBR

  16. SOSPF Neighbor States Reached Maximum Down No Recurrence Hello Received Init Two-Way Received Awaken and Unsynchronized ExStart Negotiation Done Unsynchronized Exchange Exchange Done Sleep Loading Done Sleeping Loading Full Awaken and Ready

  17. SOSPF Advertisements: Space Router-LSA (SR-LSA)

  18. SOSPF Advertisements: When an SR-LSA is Generated • An SOSPF router becomes operational • An SOSPF router changes its Propagation Delay • An SOSPF router changes its six orbital space parameters • An SOSPF router changes its calculating method tag • A new SOSPF router is found • A Link Failed

  19. SOSPF Advertisements: Area Membership-LSA (AM-LSA) Members of (Area 1:4) Mars Satellite Constellation 2’s Orbit(Area 1:4:1) M12 M2 M1 M3 Mars Satellite Constellation 2’s Orbit (Area 1:4:2) M11 M6 M4 SCBR M10 M5 M1’s Neighboring Routers List for Area 1:4 M1’s Neighboring Routers List for Area 1:4:1 M1’s AM-LSA

  20. SOSPF Advertisements: When an AM-LSA is Generated • An SOSPF router becomes operational • Invitations to a new area • Joining an area • Failed neighboring router • Bad AM-LSA • …, and a few more

  21. SOSPF Advertisements: Area Border Router (ABR) List Mars Satellite Constellation 2’s Orbit(Area 1:4:1) M12 Members of (Area 1:4) M2 M1 M3 Mars Satellite Constellation 2’s Orbit (Area 1:4:2) M11 M6 M4 SCBR M10 M5 ABR List for M1-M6

  22. Example Setup E3 E5 Sun Area 1 E4 SP E2 E1 M2 Earth Area 1:3 Mars Area 1:4 M1 M3 Earth SC Area 1:3:1 Earth SC Area 1:3:2 Mars SC Area 1:4:1 Mars SC Area 1:4:2 M4 SCBR COBR

  23. Example: SP Joins Area 1:3 1 - SP Sends hello packet to E2 and E5 2 - SP Exchanges routing information with E2 and E5 3 - E2 forwards the new LSAs to the members of area 1:3:1. 4 - E2 forwards the new LSAs to the member of area 1 5 - Members of 1:3:1 flood the received LSAs to each other. 6 - We assume that M1 does not SP’s trajectory; thus, when M1 receive SP’s SR-LSA, M1 exchanges the required information with E2. 7 - M1 floods SP to 1:4 and 1:4:1 8 - Members of 1:4 flood the SP’s SR-LSA E4 5 E5 E1 5 2 1 3 E3 3 2 SP 1 E2 4 M2 M3 8 6 7 7 8 M4 M1 SCBR COBR Time: 1:00AM

  24. Table of Contents • Space challenges • Previous Work • The SOSPF routing protocol • The Routing Algorithm • SOSPF Analysis • Dissertation Contribution

  25. The Shortest Delay Intermittent Pathway (SDIP) Routing Algorithm • Input • Cost in seconds between x and y (cxy) • Beginning of active time between x and y (bxy) • Ending of active time between x and y (exy) • Delay measured as time between x and y (dxy) i.e., • dxy = bxy + cxy • Output • Path from x to y (pxy) • Delay measured as time between x and y (dxy) pxy Link Status cxy bxy dxy exy

  26. SDIP Routing Algorithm: Valid Combined Path (Case 1) • If dik < bkj and dkj < current dij Then pij = pik + pkj dik Paths bkj dkj cij bij dij eij

  27. SDIP Routing Algorithm: Valid Combined Path (Case 2) • If dik + ckj < ekj and dik + ckj < current dij Then pij = pik + pkj dik Paths pkj ckj bkj ekj cij eij dij bij

  28. SDIP Routing Algorithm: Invalid Combined Path • If dik + ckj ≥ ekj Then pik + pkj is invalid combined path dik Paths ckj ekj

  29. Table of Contents • Space challenges • Previous Work • The SOSPF routing protocol • The Routing Algorithm • SOSPF Analysis • Dissertation Contribution

  30. Transmit 1000 Packets from Earth to Mars Packet size = 112KB – 128 KB Bandwidth = 128Kbps At 0:0:0 On August 1, 2002, Simulation Duration = 1 hour End to End Delay Simulation

  31. 1 2 Number of Propagated Packets 3 4 SOSPF Scalability Sun Area Scalability Question: How much overhead when the number of SOSPF routers increases? Answer: The answer to this question is highly dependent on the topology of the network. Planet Area Moon Area Constellation Area

  32. SOSPF Stability t1 = Time of the interruption t2 = Time of when the interruption is detected t3 = Time of when all effected nodes converge to a solution t4 = Time of the next interruption Stability = F – (D + P) F D P t3 t2 F t4 t1 Time

  33. A satellite network with a diameter of 1013 km. 5000 SOSPF routers are scattered using a uniform random function The failure interval is 6666 seconds. CT = Current Technology CT Stability Simulation Four Levels Three Levels Two Levels

  34. Dissertation Contributions • SOSPF is the routing protocol for space • Define Logical Areas • Predicted Mobility • Detects Failed Links (first dynamic error detection mechanism in space) • Maintains Routing Accuracy • SDIP routing algorithm • Provides scheduling solutions for intermittent link • Improvement of current technology • Applicable for Earth-like environment such as: • Automobile Networks • Sensor Networks

  35. Publications • Bantan, N. 2006. Space OSPF. In the Fifth Space Internetworking Workshop – presentation paper (Baltimore, Maryland, United States). September 2006. http://www.hynet.umd.edu/Space_Internet_Workshop/pres/A004.pdf • Bantan, N. and Khan, J. 2007. SOSPF- a new routing protocol for space. In Proceedings of The 25th AIAA International Communications Satellite Systems Conference (Seoul, South Korea). April 2007. • Bantan, N. and Khan, J. 2006. Space OSPF - shortest delay intermittent pathway routing with mobile routers. In the Fifth Space Internetworking Workshop – presentation paper (Baltimore, Maryland, United States). September 2006. http://www.hynet.umd.edu/Space_Internet_Workshop/pres/A008.pdf

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