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 Phobos Colony Comet Temple1 Colony Space Station Asteroid Belt Satellites Venus Satellite Constellation Moon Colony Moon Satellite Constellation Earth-Sun LaGrange Point Satellite Mercury Satellite Constellation Space Shuttle Earth Satellite Constellations

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

6 Space Communication Challenges 1. Use of network state information 2. Where is the routing table created 3. Router Mobility Predictable Predictable Unpredictable Unpredictable 4. Convergence All routing tables have converged A link is down Convergence Period Stability Period Time Stability Period Vs Convergence Period All routing tables have converged

7 More Space Communication Challenges 5. Intermittent Path 6. Long Delay Intermittent Path between k, l, and m (l, m) (k, l) + (l, m) (k, l) Time Down Up Down Up Down Up Traditional Path between k, l, and m (l, m) (k, l) + (l, m) (k, l) Down Up Down Up Down Up 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 SOSPF Areas Architecture Satellite constellation are Space colony area Celestial object area Celestial Object Area* MC1, MC2, MC3, and MC4 M1,M2, M3, M4,M5, and M6 M3 M5 M1 M6 M2 M4 Mars Celestial Object Area M1 MC3 Mars’s Satellite Constellation Area MC1 MC2 MC4 MC3 Mars’s Space Colony Area

14 Area Border Routers: Satellite Constellation Border Router (SCBR) EM1 EM2 EM3 EM5 EM4 Earth-Moon Satellite Constellation 1’s Orbit (Area 1:3:1:1) AreaMembers 1:3:1EM1, EM4, and SP1 1:3:1:1EM1, EM2, and EM3 1:3:1:2EM4 and EM5 1:3:1:3SP1 SCBR 1:3:1 1:3:1:21:3:1:1 Earth-Moon Satellite Constellation 2’s Orbit (Area 1:3:1:2) SP1 Space Shuttle 1 (Area 1:3:1:3) 1:3:1:3 Members of Area 1:3:1

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

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

17 SOSPF Advertisements: Space Router-LSA (SR-LSA) 5F00:0000:C001:0400::/56Source Satellite Address 5F00:0000:c001:2C00::/56Destination Satellite Address 3Number of tuples 2006:08:28:20:14:50 Begin time Tuple # Connection Period 15Propagation Delay 2006:08:29:40:30:05Begin time Tuple # Connection Period 20Propagation Delay 2006:08:30:23:14:50Begin time Tuple # Connection Period 20Propagation Delay

18 SOSPF Advertisements: When an SR-LSA is Generated 1. An SOSPF router becomes operational 2. An SOSPF router changes its Propagation Delay 3. An SOSPF router changes its six orbital space parameters 4. An SOSPF router changes its calculating method tag 5. A new SOSPF router is found 6. A Link Failed

19 SOSPF Advertisements: Area Membership-LSA (AM-LSA) M3 M5 M1 M12 M11 M10 Mars Satellite Constellation 2’s Orbit (Area 1:4:2) Mars Satellite Constellation 2’s Orbit (Area 1:4:1) SCBR M6 M2 M4 Members of (Area 1:4) 5F00:0000: B020::/48 Source Satellite Address 1# of tuples 1:4Area ID # 1 M1, M12 Area Members 2007:01:11 :20:14:50 Area Start Time 1400 Area Period 1:4:1Area ID # 2 M1,M2,M3, M4,M5,M6 Area Members 2007:28:28 :20:14:50 Area Start Time Area Period M1’s AM-LSA 1Number of entries M1,M12Neighboring Routers #1 2007:01:11:20:14:50Neighboring Start Time 1400Neighboring Period M1’s Neighboring Routers List for Area 1:4 1Number of entries M1,M2,M3,M4,M5,M6Neighboring Routers #1 2007:08:28:20:14:50Neighboring Start Time 50400Neighboring Period M1’s Neighboring Routers List for Area 1:4:1

20 1. An SOSPF router becomes operational 2. Invitations to a new area 3. Joining an area 4. Failed neighboring router 5. Bad AM-LSA 6. …, and a few more SOSPF Advertisements: When an AM-LSA is Generated

21 SOSPF Advertisements: Area Border Router (ABR) List Expiration TimeMembership Start TimeArea IDArea Border Router's ID 2007:01:11:20:35:132007:01:11:20:14:501:4 M1 2007:08:29:10:14:502007:08:28:20:14:501:4:1 M3 M5 M1 M12 M11 M10 Mars Satellite Constellation 2’s Orbit (Area 1:4:2) Mars Satellite Constellation 2’s Orbit (Area 1:4:1) SCBR M6 M2 M4 Members of (Area 1:4) ABR List for M1-M6

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

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

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 (c xy ) –Beginning of active time between x and y (b xy ) –Ending of active time between x and y (e xy ) –Delay measured as time between x and y (d xy ) i.e., d xy = b xy + c xy Output –Path from x to y (p xy ) –Delay measured as time between x and y (d xy ) Up Down Time e xy b xy d xy Link Status c xy p xy

26 SDIP Routing Algorithm: Valid Combined Path (Case 1) If d ik < b kj and d kj < current d ij Then p ij = p ik + p kj p ik p kj p ik +p kj Time d ik b kj Paths d kj d ij b ij e ij c ij

27 SDIP Routing Algorithm: Valid Combined Path (Case 2) p ik p ik +p kj Time c kj b kj e kj d ik Paths If d ik + c kj < e kj and d ik + c kj < current d ij Then p ij = p ik + p kj d ij b ij e ij c ij p kj

28 SDIP Routing Algorithm: Invalid Combined Path If d ik + c kj ≥ e kj Then p ik + p kj is invalid combined path p ik p kj p ik +p kj Time c kj Paths e kj d ik

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

30 End to End Delay Simulation 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

31 SOSPF Scalability Scenario Levels nnnn 2nn/2 3nn/4n/8n/16 4nn/24n/36n/ Number of Propagated Packets 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. Sun Area Planet Area Moon Area Constellation Area

32 SOSPF Stability t 1 = Time of the interruption t 2 = Time of when the interruption is detected t 3 = Time of when all effected nodes converge to a solution t 4 = Time of the next interruption Stability = D P F t4t4 t2t2 t1t1 t3t3 Time F – (D + P) F

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

34 Dissertation Contributions 1. 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 2. 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 Space OSPF. In the Fifth Space Internetworking Workshop – presentation paper (Baltimore, Maryland, United States). September Bantan, N. and Khan, J SOSPF- a new routing protocol for space. In Proceedings of The 25th AIAA International Communications Satellite Systems Conference (Seoul, South Korea). April Bantan, N. and Khan, J Space OSPF - shortest delay intermittent pathway routing with mobile routers. In the Fifth Space Internetworking Workshop – presentation paper (Baltimore, Maryland, United States). September