1. An Overview of Disruption Tolerant Networking and Applications Kevin K. Gifford University of Colorado BioServe Space Technologies 16-January-2013 1 FISO DTN Overview

2. Presentation Outline (what to expect) DTN on the ISS CGBA payloads ESA telerobotics and testing JAXA DTN experiments ISS Institutional DTN! SPHERES and DTN DTN for Public Safety PSBN Campus Party 2014 DTN Challenge ISS / crew involvement General Problem Statement 2

3. Operational Benefits of Delay Tolerant Networking Enables data transmission and receipt across intermittently connected and disrupted networks typical of space operations Provides increase in telemetry and science return - both quantity and efficiency Improves communication robustness via multiple network paths and multiple cooperating assets Creates an increase in situational awareness and improved mission safety Enables interoperability of multi-agency heterogeneous communication assets Improves operations by automating data transmissions and routing Delay, or disruptive, tolerant networks make use of automated store-and- forward techniques within the network in order to compensate for intermittent link connectivity typical of space & mobile environments. The reliable delivery of messages in such a “disconnected” network greatly benefits application layer operations, preventing data loss and associated labor costs. Presentation Summary 3 3

4. Since the start of the space age, communications between spacecraft and ground stations has been characterized by simple, point-to-point data transmission. Problem Statement While Internet protocols this may work well for certain environments, they do not work well for many space-based and wireless mobile environments characterized by intermittent link connectivity, long or variable transmission delay, asymmetric data rates, and potentially high bit error rates (BER). Existing Internet protocols have not been augmented for extension for space communications and rely upon several fundamental assumptions built into the terrestrial Internet architecture. 4 4

5. 5 09-Aug-2011 Evolution of Terrestrial Networking 5

6. Why Packetized Communications? CxP 70022-01, C3I Interoperability Standards Book, Vol.1, pg. 15 6 6

7. Terrestrial Internet Protocol Layers Application Transport Network Link Physical Source Destination TCP IP Link 1 Link 2 Link 3 PHY 1 PHY 2 PHY 3 7

8. Assumptions built into terrestrial Internet An end-to-end path between the source and the destination will exist for the entire communication session Key: Source or destination node Router Packet (corresponding Acknowledgements not shown) Connected link Disconnected link Source Destination Retransmission based on immediate feedback from data receivers enables effective recovery from errors There are relatively consistent symmetric data rates in both directions between the sender and the receiver Relatively little loss or data corruption (low bit error rate, BER) 09-Aug-2011 8 8

9. Time source destination ON OFF Comm Link 1 Comm Link 2 Comm Link 3 Comm Link 4 MCC Earth Station Relay Rover One One dataset, repeat attempts With IP: User must wait for a continuous end-to- end path. Data are discarded by IP routers if next hop is not available Surface Station 9 Why not utilize Internet protocols? 9

10. Bundle Layer: An overlay network architecture Application Transport Network Link Physical Source Destination TCP IP Link 1 Link 2 Link 3 PHY 1 PHY 2 PHY 3 Bundle Layer Bundle Layer Bundle Layer Bundle Layer 10

11. Store-and-Forward Messaging Node A Storage Node B Storage Node C Storage Node D Storage DTNs overcome the “Internet assumptions” of intermittent connectivity, long or variable delay, asymmetric data rates and high BER utilizing store-and- forward messaging The data stores in a DTN network are non-volatile (or persistent) storage such as hard disks 11

12. Store-and-Forward Messaging Node A Storage Node B Storage Node C Storage Node D Storage DTN routers need persistent storage for their message queues for the following reasons: A communication link to the next hop may be unavailable (no path) One node in a communicating pair may send or receive data much faster or more reliably than the other node A previously transmitted message (or fragment) may need to be retransmitted if an error occurs upstream 12

13. DTN is a “non-conversational” protocol Bundle Layer Bundle On intermittently connected links with long (> 2 sec) delays, conversational protocols with chatty acknowledgments will fail or be impractical DTN bundle layers communicate between themselves utilizing simple sessions with minimized round-trips; any acknowledgement from the receiving node is optional Bundle Layer Optional Acknowledgement Lower Layers Protocol-dependent transfers (e.g., TCP, UDP, IP) Lower Layers Protocol-dependent acknowledgements 13

14. Store and Forward source destination ON OFF Comm Link 1 Comm Link 2 Comm Link 3 Comm Link 4 MCC Relay Rover Four Four datasets With DTN : Data are held at DTN routers and continue to destination when next hop is available. Surface Station In stressed communications environments: Increased VOLUME of data, delivered FASTER, i.e. higher GOODPUT and lower LATENCY DTN operations in intermittently-connected environments 14

15. Reliability in DTN networks Custody Transfer: Delegation of retransmission responsibility to an accepting node so that the sending node can recover its transmission resources; the accepting node returns a custodial- acceptance acknowledgment to the previous custodian Return Receipt: Confirmation to the source, or its reply-to entity, that the bundle has been received at the destination CT Custody Transfer (hop-by-hop) Return Receipt* (end-to-end) Key: Bundle delivery Acknowledgement Custody Transfer * Transfers actually occur hop-by-hop, and they may go to a reply-to-entity CT  In addition to custody-transfer acceptance 15

16. Reliability in DTN networks Custody-Transfer Notification: Notification to the source, or its reply-to entity, when a node accepts custody transfer of the bundle CT Custody Transfer (hop-by-hop) Return Receipt* (end-to-end) Custody Transfer Notification + * CT 16

17. DTN and the Bundle Protocol IRTF RFCs DTN Architecture – RFC 4838 – Bundle Protocol – RFC 5050 – Bundle Security Protocol – RFC 6257 – Licklider Transport Protocol – RFC 5327 – Other Drafts in progress Experimental Drafts – Aggregate Custody Signals, ACS 17

18. Enables the transition from point-to-point communications … to a truly networked Space Internet with automated data routing & transmission Why DTN is important for Disconnected Operations and Space Communications 18 Delay, or disruptive, tolerant networks make use of automated store-and-forward techniques within the network in order to compensate for intermittent link connectivity typical of space environments. The reliable delivery of messages in such a “disconnected” network greatly benefits the operation of space command and communications applications, preventing data loss and associated labor costs. 18

19. Interoperability: Standardized DTN protocol suite enables interoperability of multi- agency communication assets Improved Operations: DTN automated data transmissions and routing allow for reduced scheduling; DTN enables automated data transmission and receipt across intermittently connected and disrupted networks typical of space operations Security: DTN Bundle Security Protocol allows for authentication and encryption, even on links where not previously used (i.e. Ku-Band uplink) Link Efficiency and Utilization: DTN enables more reliable and efficient data transmissions resulting in more usable bandwidth Quality of Service (QoS): DTN QoS allows for priorities to be assigned to different data types Redundancy and Robustness: DTN improves communication by having multiple network paths and assets for communication hops Situational Awareness: DTN store-and- forward mechanism along with automatic retransmission provides more insight into events during communication outages Exploration Missions: ISS DTN operational usage and testing will allow NASA to mature exploration communication protocols for future missions (LEO, NEO, L1/L2, Deep Space) NASA benefits for DTN onboard ISS activities 19

20. ISS Boulder CU DTN Internet NASA Long Term Vision: ISS as an International DTN Laboratory Munich, Darmstadt, Noordwijk MCC Moscow Tsukuba Huntsville HOSC METERON DTN Internet JAXA Kibo ESA Columbus KONTUR-2S-band Roscosmos Zvezda LUCH:VHF BRI router BRI VLAN ISS payload LAN US DestinyDRTS:K-band TDRS:S&K-band ISS payload LAN CGBAT61PT61P? EIU 20

21. CGBA-5 DTN Payload in EXPRESS Rack on the ISS 21

22. DTN can significantly improve link utilization efficiency Fundamental observation: Until CGBA-DTN, NASA did not allow uplink acknowledgement of files/data transmitted from the ISS and received on groundside destination(s) CU DTN G/W HOSC DTN G/W TDRS MSFC CGBA-5 Boulder 22

23. CU DTN G/W US Destiny Lab: ISS Payloads HOSC DTN G/W TDRS MSFC ISS CGBA-5 ISS payload LAN Boulder Goals: Provide continuous flight testing & verifications for DTN evolution Provision of Payload LAN DTN communications Provide initial ISS DTN Gateway P/L LAN operational platform Improve ISS forward link utilization Increase ISS scientific utilization with improved communications DTN Project: CGBA ISS Payloads and MSFC HOSC CGBA-4 History CGBA-5 DTN operational 24/7 since May-2009 CGBA-4 DTN operational 24/7 since Apr-2010 HOSC POIC system DTN integration ISS Cadre acceptance of DTN operations HOSC DTN G/W build-out Benefits to NASA Higher-efficiency link utilization via DTN improves ISS utilization by increasing data throughput (goodput) DTN decreases the need, and attendant infrastructure costs, for custom Mission or Payload Operations Control Centers DTN decreases mission operations control center labor costs via automated (unattended, lights-out) spacecraft/satellite/payload command and telemetry (C&T) transmission and receipt. DTN gives earliest possible insight for improved situational awareness for critical ISS management functions 23

24. ISS Boulder CU DTN Internet DTN-on-ISS: ESA METERON Robotics Program Munich, Darmstadt, Noordwijk MCC Moscow Tsukuba Huntsville HOSC METERON DTN Internet JAXA Kibo ESA Columbus KONTUR-2S-band Roscosmos Zvezda LUCH:VHF BRI router BRI VLAN ISS payload LAN US DestinyDRTS:K-band TDRS:S&K-band ISS payload LAN CGBAT61PT61P? EIU 24

25. Reference architectureISS as test bed ESA METERON Project METERON: Multipurpose End-To-End Robotics Operations Network 25

26. ESA “OPSCOM” network topologies: ESA-led activity C&T / H&S DTN DTN Node DTN Pass- though Boulder POCC CGBA GSE Huntsville HOSC ESOC ESA Columbus US Destiny TDRS ISS payload LAN CGBA METERN GSE METERN Laptop OpsCom-1 Configuration Boulder POCC CGBA GSE Huntsville HOSC ESOC ESA Columbus US Destiny TDRS ISS payload LAN CGBA METERN GSE METERN Laptop OpsCom-2 Configuration B.USOC Darmstadt B.USOC Darmstadt or ESTEC CU-Boulder to B.USOC VPN 26

27. ISS Boulder CU DTN Internet DTN-on-ISS: JAXA DRTS-to-ISS DTN Project Munich, Darmstadt, Noordwijk MCC Moscow Tsukuba Huntsville HOSC METERON DTN Internet JAXA Kibo ESA Columbus KONTUR-2S-band Roscosmos Zvezda LUCH:VHF BRI router BRI VLAN ISS payload LAN US DestinyDRTS:K-band TDRS:S&K-band ISS payload LAN CGBAT61PT61P? EIU 27

28. ISS Boulder Tsukuba Huntsville HOS C JAXA Kibo ISS payload LAN US Destiny DRTS:K-band TDRS:S&K-band CGBA EIU Planned JAXA DTN Activities on ISS using their Data Technology Research Satellite (DRTS) CU Boulder Internet Tsukuba HOSC Huntsville Internet DTN Goal: enable JAXA to experiment with DTN by exchanging data with NASA CBGA payloads over JAXA’s Ka band (rain-fade prone) DTRS links Control Center JAXA Testbed 28

29. ISS Ops LAN users Ops LAN wireless users ISS Ops LAN DTN G/W CU- Boulder MSFC HOSC Internet DTN G/W DTN G/W DTN G/W JSC MCC JSC OTF JSC LWT JSC ETSL White Sands Ground networks JAXA Kibo / ESA ColumbusUS Destiny ISS Payload LAN DTN G/W TDRS:S&K-band ISS “Institutional” DTN Gateway Concept System Architecture 29

30. National Public Safety Broadband Network (PSBN) National Broadband Plan (Obama) $7B to support PSBN roll-out: NIST, NTIA oversight Nationwide wireless network for first responders “FirstNet” is PSBN organizational board DTN for Public Safety “Out-of-network” scenarios 30

31. 31 National Public Safety Broadband Network (PSBN) 31

32. Campus Party 2014: Silicon Valley What is Campus Party An annual week long, 24-hours-a-day technology festival where thousands of “campuseros” (hackers, developers, gamers and geeks) equipped with laptops camp on-site and immerse themselves in a truly unique environment. CP2014 DTN Challenge Concept is to hold contest for DTN applications for the ISS Have ISS crew announce top 3 winners Winner(s) get expert panel assistance to deploy prototype on ISS 32

33. ISS SPHERES Smartphone DTN Project SPHERES: Synchronized Position Hold Engage Re-orient Experimental Satellites SPHERES Ground command Robot executes plan commands Robot collects images & data 33 Awesomeness: What if I had a RFID reader on a SPHERES-Bot for improved IMS?

34. ISS Important Research and Development for Flight Ops: Aggregate Custody Signals, ACS Aggregate Custody Signals, ACS QoS and Security QoS and Security DTN multicast DTN multicast DTN Border Gateways DTN Border Gateways Boulder CU DTN Internet DTN evolution Munich, Darmstadt, Noordwijk MCC Moscow Tsukuba Huntsville HOSC METERON DTN Internet JAXA Kibo ESA Columbus KONTUR-2S-band Roscosmos Zvezda LUCH:VHF BRI router BRI VLAN ISS payload LAN US DestinyDRTS:K-band TDRS:S&K-band ISS payload LAN CGBAT61PT61P? EIU 34

35. End of presentation The PSBN is very important

36. DTN routing: address dynamicity inherent in DTNs Forward Work / Open Research Topics 36 DTN Security: BSP, computational complexity DTN Quality of Service: Really, data prioritization: define policies as opposed to mechanisms DTN Aggregate Custody Signals: Similar to TCP-Sack DTN Border Gateways: more network-infrastructure oriented DTN multicast: efficient transmission to multiple recipients