a routing protocol for space communication

11

A Routing Protocol for Space A Routing Protocol for Space CommunicationCommunication

By: Nouman Bantan By: Nouman Bantan

Advisor: Dr. Javed I. KhanAdvisor: Dr. Javed I. Khan

Friday, February 16, 2007Friday, February 16, 2007

22

Current MobilityCurrent Mobility

33

Space MobilitySpace Mobility

44

Future NetworkFuture Network

Mars Colonies

Mars Satellite Constellation

Phobos Colony

Comet Temple1 Colony

Space Station

AsteroidBelt Satellites

Venus Satellite Constellation

MoonColony

Moon Satellite Constellation

Earth-Sun LaGrange Point Satellite

Earth-Sun LaGrange Point Satellite

Mercury Satellite Constellation

Space Shuttle

EarthSatellite Constellations

55

Table of ContentsTable of Contents

Space ChallengesSpace Challenges

Previous WorkPrevious Work

Our Space Routing ProtocolOur Space Routing Protocol

The Routing AlgorithmThe Routing Algorithm

SOSPF AnalysisSOSPF Analysis

Dissertation ContributionDissertation Contribution

66

Space Communication ChallengesSpace Communication Challenges

1.1. Use of network state informationUse of network state information2.2. Where is the routing table createdWhere is the routing table created3.3. Router MobilityRouter Mobility

PredictablePredictable UnpredictableUnpredictable

4.4. ConvergenceConvergence

All routing tables have converged

A link is down

Convergence Period

Stability Period

Time

Stability Period Vs Convergence Period

All routing tables have converged

77

More Space Communication More Space Communication ChallengesChallenges

5.5. Intermittent PathIntermittent Path

6.6. Long DelayLong 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

88


Space challengesSpace challenges


The SOSPF routing protocolThe SOSPF routing protocol




99

Previous Works: ASCoTPrevious Works: ASCoT

The NASA Autonomous Space Communications The NASA Autonomous Space Communications Technology (ASCoT) [Gnawali 05Technology (ASCoT) [Gnawali 05]]– depends on underlying systems which providesdepends on underlying systems which provides

Navigation information Navigation information Local status Local status Ability to send and receive messagesAbility to send and receive messages

Link trajectories, together with link attributes are Link trajectories, together with link attributes are disseminated throughout the network. disseminated throughout the network. Then, each router can independently compute Then, each router can independently compute paths using a modified Dijkstra’s algorithmpaths using a modified Dijkstra’s algorithmNo intermittent links supportNo intermittent links supportSingle point of failureSingle point of failure

1010

Previous Work: STRFPrevious Work: STRF

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

1111








1212

SOSPF Routing ProtocolSOSPF Routing Protocol

Area StructureArea StructureHello ProtocolHello ProtocolNeighbor StructureNeighbor StructurePredictable ModelPredictable ModelAdvertisementsAdvertisementsDatabase Exchange ProtocolDatabase Exchange ProtocolFloodingFloodingCalculating Routing TableCalculating Routing Table

1313

SOSPF Areas ArchitectureSOSPF Areas Architecture

Satellite constellation areSatellite constellation are

Space colony areaSpace colony area

Celestial object areaCelestial 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

M1MC3

Mars’s Satellite Constellation Area

MC1 MC2

MC4MC3

Mars’s Space Colony Area

1414

Area Border Routers: Area Border Routers: Satellite Constellation Border Router (SCBR)Satellite Constellation Border Router (SCBR)

EM1

EM2

EM3EM5

EM4

Earth-Moon Satellite Constellation 1’s Orbit (Area 1:3:1:1)

Area Members

1:3:1 EM1, EM4, and SP1

1:3:1:1 EM1, EM2, and EM3

1:3:1:2 EM4 and EM5

1:3:1:3 SP1

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

1515

Area Border Routers: Area Border Routers: Celestial Object Border Router (COBR)Celestial Object Border Router (COBR)

E3

EM1

EM2

EM3

E1

E2

EM5

EM4

E5

E6

E4

SCBRCOBR

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

1616

SOSPF Neighbor StatesSOSPF Neighbor States

ExStart

Down

Init

Exchange

LoadingFullSleepingAwaken and Ready

Awaken and Unsynchronized

Reached Maximum

Sleep

Unsynchronized

No Recurrence Hello Received

Two-Way Received

Exchange Done

Negotiation Done

Loading Done

1717

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

Source Satellite Address 5F00:0000:C001:0400::/56

Destination Satellite Address 5F00:0000:c001:2C00::/56

Number of tuples 3

Tuple # 1

Begin time 2006:08:28:20:14:50

Connection Period 14400

Propagation Delay 15

Tuple # 2

Begin time 2006:08:29:40:30:05



Tuple # 3

Begin time 2006:08:30:23:14:50



1818

SOSPF Advertisements: SOSPF Advertisements: When an SR-LSA is GeneratedWhen an SR-LSA is Generated

1.1. An SOSPF router becomes operationalAn SOSPF router becomes operational2.2. An SOSPF router changes its An SOSPF router changes its

Propagation DelayPropagation Delay3.3. An SOSPF router changes its six orbital An SOSPF router changes its six orbital

space parametersspace parameters4.4. An SOSPF router changes its calculating An SOSPF router changes its calculating

method tagmethod tag5.5. A new SOSPF router is foundA new SOSPF router is found6.6. A Link FailedA Link Failed

1919

SOSPF Advertisements: SOSPF Advertisements: Area Membership-LSA (AM-LSA) 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)

Source Satellite Address

5F00:0000:B020::/48

# of tuples 1

# 1

Area ID 1:4

Area Members

M1, M12

Area Start Time

2007:01:11:20:14:50

Area Period

1400

# 2

Area ID 1:4:1

Area Members

M1,M2,M3, M4,M5,M6

Area Start Time

2007:28:28:20:14:50

Area Period

50400

M1’s AM-LSA

Number of entries 1

#1

Neighboring Routers M1,M12

Neighboring Start Time 2007:01:11:20:14:50

Neighboring Period 1400

M1’s Neighboring Routers List for Area 1:4

Number of entries 1

#1

Neighboring RoutersM1,M2,M3,M4,M5,M6

Neighboring Start Time 2007:08:28:20:14:50

Neighboring Period 50400

M1’s Neighboring Routers List

for Area 1:4:1

2020

1.1. An SOSPF router becomes An SOSPF router becomes operationaloperational

2.2. Invitations to a new areaInvitations to a new area

3.3. Joining an areaJoining an area

4.4. Failed neighboring routerFailed neighboring router

5.5. Bad AM-LSA Bad AM-LSA

6.6. ……, and a few more, and a few more

SOSPF Advertisements: SOSPF Advertisements: When an AM-LSA is GeneratedWhen an AM-LSA is Generated

2121

SOSPF Advertisements: SOSPF Advertisements: Area Border Router (ABR) ListArea Border Router (ABR) List

Area Border Router's ID

Area ID Membership Start Time Expiration Time

M11:4 2007:01:11:20:14:50 2007:01:11:20:35:13

1:4:1 2007:08:28:20:14:50 2007:08:29:10:14:50

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

2222

Example SetupExample Setup

M3

M2E1

E5E3

M1

M4

E2SPE4

SCBRCOBR

EarthArea 1:3

EarthSC Area

1:3:2

Earth SC Area

1:3:1

SunArea

1

MarsArea 1:4

MarsSC Area

1:4:2

MarsSC Area

1:4:1

2323

Example: SP Joins Area 1:3Example: SP Joins Area 1:31 - SP Sends hello packet to E21 - SP Sends hello packet to E2 and E5 and E5 2 - SP Exchanges routing2 - SP Exchanges routing information with E2 and E5 information with E2 and E5 3 - E2 forwards the new LSAs to3 - E2 forwards the new LSAs to the members of area 1:3:1.the members of area 1:3:1.4 - E2 forwards the new LSAs to4 - E2 forwards the new LSAs to the member of area 1 the member of area 1 5 - Members of 1:3:1 flood the5 - Members of 1:3:1 flood the received LSAs to each other.received LSAs to each other.6 - We assume that M1 does not6 - We assume that M1 does not SP’s trajectory; thus, when M1SP’s trajectory; thus, when M1 receive SP’s SR-LSA, M1receive SP’s SR-LSA, M1 exchanges the requiredexchanges the required information with E2. information with E2. 7 - M1 floods SP to 1:4 and 1:4:1 7 - M1 floods SP to 1:4 and 1:4:1 8 - Members of 1:4 flood the SP’s 8 - Members of 1:4 flood the SP’s

SR-LSA SR-LSA

M3M2

E3

E5

M1

M4

E1

SPE2

5

123

1

Time: 1:00AM

E4

3

5

8

7 7

8

4

6

SCBRCOBR

2

2424








2525

The Shortest Delay Intermittent The Shortest Delay Intermittent Pathway (SDIP) Routing AlgorithmPathway (SDIP) Routing Algorithm

InputInput– Cost in seconds between Cost in seconds between xx and and yy ( (ccxyxy))– Beginning of active time between x and y (Beginning of active time between x and y (bbxyxy))– Ending of active time between x and y (Ending of active time between x and y (eexyxy))– Delay measured as time between Delay measured as time between xx and and yy ( (ddxyxy) i.e.,) i.e.,

ddxyxy = = bbxyxy + + ccxyxy

OutputOutput– Path from Path from xx to to yy ( (ppxyxy))– Delay measured as time between Delay measured as time between xx and and yy ( (ddxyxy))

Up

Down

Time exybxy dxy

Link

Sta

tus

cxypxy

2626

SDIP Routing Algorithm: SDIP Routing Algorithm: Valid Combined Path (Case 1)Valid Combined Path (Case 1)

If If ddikik < < bbkj kj and dand dkjkj < current < current ddijij

Then Then ppijij = p = pikik + + ppkjkj

pik

pkj

pik+pkj

Time

dik

bkjPat

hs

dkj

dijbij eij

cij

2727

SDIP Routing Algorithm: SDIP Routing Algorithm: Valid Combined Path (Case 2)Valid Combined Path (Case 2)

pik

pik+pkj

Time

ckj

bkj ekj

dik

Pat

hs

If If ddikik + + cckjkj < < eekj kj and dand dikik + + cckjkj < current < current ddijij

Then Then ppijij = p = pikik + + ppkjkj

dijbijeij

cij

pkj

2828

SDIP Routing Algorithm: SDIP Routing Algorithm: Invalid Combined PathInvalid Combined Path

If If ddikik + + cckjkj ≥ ≥ eekjkj

ThenThen p pikik + + ppkj kj is invalid combined pathis invalid combined path

pik

pkj

pik+pkj

Time

ckjPat

hs

ekj

dik

2929








3030

End to End Delay SimulationEnd to End Delay Simulation

Transmit 1000 Packets from Earth to MarsTransmit 1000 Packets from Earth to MarsPacket size = 112KB – 128 KBPacket size = 112KB – 128 KBBandwidth = 128Kbps Bandwidth = 128Kbps At 0:0:0 On August 1, 2002,At 0:0:0 On August 1, 2002,Simulation Duration = 1 hourSimulation Duration = 1 hour

Average Delay for Transmissions Between an Earth Satellite and a Mars Satellite

0

500

1000

1500

1 2 3 4 5 6 7Scnario Number

Sec

onds SOSPF

ASCoT

STRF

1)

2)

3)

4)

5)

6)

7)

3131

SOSPF ScalabilitySOSPF Scalability

Scenario

Levels

1 2 3 4

1 n n n n

2 n n/2 n/2 n/2

3 n n/4 n/8 n/16

4 n n/24 n/36 n/48

Propagated Packets Per Satellite Router

1

10

100

1000

10000

0 30

0

60

0

90

0

12

00

15

00

18

00

21

00

24

00

27

00

30

00

Number of Satellite Routers

2

1

3

4

Num

ber

of

Pro

paga

ted

Pac

kets

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

3232

SOSPF StabilitySOSPF Stability

tt11 = = Time of the interruptionTime of the interruption

tt22 = = Time of when the interruption is detectedTime of when the interruption is detected

tt33 = = Time of when all effected nodes converge to a solutionTime of when all effected nodes converge to a solution

tt44 = = Time of the next interruptionTime of the next interruption

Stability =Stability =

D P

Ft4

t2

t1

t3

Time

F – (D + P)F – (D + P)

F F

3333

Stability SimulationStability Simulation

Two LevelsThree Levels

Four Levels

A satellite network with a diameter of 1013 A satellite network with a diameter of 1013 km.km.5000 SOSPF routers are scattered using a 5000 SOSPF routers are scattered using a uniform random functionuniform random functionThe failure interval is 6666 seconds. The failure interval is 6666 seconds. CT = Current TechnologyCT = Current Technology

0

0.2

0.4

0.6

0.8

1

0.1

1 10 100

1000

10000Network Diameter (109 km)

(F -

(D

+ P

))/F RT

Two LevelsThree LevelsFour Levels

Moon

MarsJupiter

Neptune

0

0.2

0.4

0.6

0.8

1

0.1

1 10 100

1000

10000Network Diameter (109 km)

(F -

(D

+ P

))/F RT

Two LevelsThree LevelsFour Levels

Moon

MarsJupiter

Neptune

CT

3434

Dissertation ContributionsDissertation Contributions

1.1. SOSPF is the routing protocol for spaceSOSPF is the routing protocol for space– Define Logical AreasDefine Logical Areas– Predicted MobilityPredicted Mobility– Detects Failed Links (first dynamic error detection Detects Failed Links (first dynamic error detection

mechanism in space)mechanism in space)– Maintains Routing AccuracyMaintains Routing Accuracy

2.2. SDIP routing algorithm SDIP routing algorithm – Provides scheduling solutions for intermittent link– Improvement of current technology– Applicable for Earth-like environment such as:

Automobile NetworksSensor Networks

3535

PublicationsPublications

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

a routing protocol for space communication

Documents

members of area

space communicationby

3sp1area border routers

lagrange point satelliteearth

2sp1space shuttle

convergeda link

link attributes

underlying systems