An Overview of Disruption Tolerant Networking and Applications

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

2. Presentation Outline (what to expect) • General Problem Statement • 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

3. Presentation Summary 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. 3

4. Problem Statement Since the start of the space age, communications between spacecraft and ground stations has been characterized by simple, point-to-point data transmission. 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

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

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

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

8. Assumptions built into terrestrial Internet Destination Source An end-to-end path between the source and the destination will exist for the entire communication session 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 Key: Source or destination node Connected link Relatively little loss or data corruption (low bit error rate, BER) Router Disconnected link Packet (corresponding Acknowledgements not shown) 8 09-Aug-2011

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

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

11. Store-and-Forward Messaging Node A Node B Node D Node C Storage Storage Storage 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

12. Store-and-Forward Messaging Node A Node B Node D Node C Storage Storage Storage 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

13. DTN is a “non-conversational” protocol Bundle Bundle Layer Bundle Layer Optional Acknowledgement Protocol-dependent transfers (e.g., TCP, UDP, IP) Lower Layers Lower Layers Protocol-dependent acknowledgements • 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

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

15. Reliability in DTN networks Custody Transfer (hop-by-hop) CT CT CT Return Receipt* (end-to-end) Key: Bundle delivery * Transfers actually occur hop-by-hop, and they may go to a reply-to-entity Acknowledgement + In addition to custody-transfer acceptance CT Custody Transfer • 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

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

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

18. Why DTN is important for Disconnected Operations and Space Communications Enables the transition from point-to-point communications … to a truly networked Space Internet with automated data routing & transmission 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. NASA benefits for DTN onboard ISS activities 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) Link Efficiency and Utilization: DTN enables more reliable and efficient data transmissions resulting in more usable bandwidth Redundancy and Robustness: DTN improves communication by having multiple network paths and assets for communication hops 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 Situational Awareness: DTN store-and-forward mechanism along with automatic retransmission provides more insight into events during communication outages Quality of Service (QoS): DTN QoS allows for priorities to be assigned to different data types Interoperability: Standardized DTN protocol suite enables interoperability of multi-agency communication assets Security: DTN Bundle Security Protocol allows for authentication and encryption, even on links where not previously used (i.e. Ku-Band uplink)

20. NASA Long Term Vision: ISS as an International DTN Laboratory ISS JAXA Kibo US Destiny ESA Columbus Roscosmos Zvezda ISS payload LAN ISS payload LAN EIU CGBA T61P T61P? BRI VLAN BRI router TDRS: S&K-band DRTS: K-band LUCH: VHF KONTUR-2 S-band Munich, Darmstadt, Noordwijk Huntsville MCC Moscow Tsukuba DTN HOSC DTN METERON Internet Internet Boulder CU DTN

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

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) CGBA-5 TDRS MSFC HOSC DTN G/W CU DTN G/W Boulder

23. DTN Project: CGBA ISS Payloads and MSFC HOSC ISS • 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 US Destiny Lab: ISS Payloads ISS payload LAN CGBA-4 CGBA-5 TDRS • 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 MSFC • 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 HOSC DTN G/W CU DTN G/W Boulder

24. DTN-on-ISS: ESA METERON Robotics Program ISS JAXA Kibo US Destiny ESA Columbus Roscosmos Zvezda ISS payload LAN ISS payload LAN EIU CGBA T61P T61P? BRI VLAN BRI router TDRS: S&K-band DRTS: K-band LUCH: VHF KONTUR-2 S-band Munich, Darmstadt, Noordwijk Huntsville MCC Moscow Tsukuba DTN HOSC DTN METERON Internet Internet Boulder CU DTN

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

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

27. DTN-on-ISS: JAXA DRTS-to-ISS DTN Project ISS JAXA Kibo US Destiny ESA Columbus Roscosmos Zvezda ISS payload LAN ISS payload LAN EIU CGBA T61P T61P? BRI VLAN BRI router TDRS: S&K-band DRTS: K-band LUCH: VHF KONTUR-2 S-band Munich, Darmstadt, Noordwijk Huntsville MCC Moscow Tsukuba DTN HOSC DTN METERON Internet Internet Boulder CU DTN

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

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

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

31. National Public Safety Broadband Network (PSBN)

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

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

34. DTN evolution ISS JAXA Kibo US Destiny ESA Columbus Roscosmos Zvezda ISS payload LAN ISS payload LAN EIU CGBA T61P T61P? BRI VLAN BRI router TDRS: S&K-band DRTS: K-band LUCH: VHF KONTUR-2 S-band Munich, Darmstadt, Noordwijk Huntsville MCC Moscow Tsukuba DTN HOSC DTN METERON Internet Internet • Important Research and Development for Flight Ops: • Aggregate Custody Signals, ACS • QoS and Security • DTN multicast • DTN Border Gateways Boulder CU DTN

35. End of presentation The PSBN is very important

36. Forward Work / Open Research Topics • DTN routing: address dynamicity inherent in DTNs • 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 36