5/22/2008 RMJ-1 DINET Deep Impact Network Experiment Adapted from Technical Summary, Management and Project Engineering DINET CDR 6/2/08 Ross Jones

5/22/2008 RMJ-2 DINET Summary DINET is a technology validation experiment of JPL’s implementation of Delay-Tolerant Networking protocols. The DINET development is to produce a version of JPL’s implementation of Delay-Tolerant Networking protocols in flight and ground SW at TRL 8. –The DINET SW is to be of sufficient quality that future flight projects can easily use it at low risk. DINET is to be implemented on the Deep Impact spacecraft and is being closely coordinated with the EPOXI project. DINET operations will be performed during the Deep Impact spacecraft team “stand down” after EPOCH operations and before the start of development for DIXI operations, i.e. Oct, 2008 –DINET requires no trajectory change. DINET developments and operations will be on a non-interference basis with EPOXI to the maximum extent possible. Note: DINET data traffic will be AMS messages containing small images.

5/22/2008 RMJ-3 Earth MarsPhobos Orbiter Relay (surface asset) Basic Experiment Network Topology (DI s/c acts as orbiter relay)

5/22/2008 RMJ-4 Load/Go Deep ImpactDSOTDINET EOC in PTL stot EVRs “Earth” “Mars” “Phobos” Experiment database Load/Go bundles log msgs BRS TCP space links image files LTP/UDP serverclient serverclient serverclient Experiment 1: Send images from nodes 12 to node 8 via nodes 6, 3, 7 (the Deep Impact spacecraft), 2, 4. Also send images from nodes 20 to node 8 via nodes 10, 5, 7 (the Deep Impact spacecraft), 2, 4. NOTE: Deep Impact science spacecraft is functioning as a router (infrastructure).

5/22/2008 RMJ-5 Load/Go Deep ImpactDSOTDINET EOC in PTL stot EVRs “Earth” “Mars” “Phobos” Experiment database Load/Go bundles log msgs BRS TCP space links image files LTP/UDP serverclient serverclient serverclient Experiment 2: Send Load/Go directive loads from node 16 to node 12 via nodes 4, 2, 7, 3, 6. Also from 16 to 20 via 4, 2, 7, 5, 10.

5/22/2008 RMJ-6 Load/Go Deep ImpactDSOTDINET EOC in PTL stot EVRs “Earth” “Mars” “Phobos” Experiment database Load/Go bundles log msgs BRS TCP space links image files LTP/UDP serverclient serverclient serverclient Experiment 3: Omit a contact between 7 and 5 and repeat, forcing images from 20 to travel via 10, 6, 3, 7, 2, 4 and forcing directive loads to 20 to travel via 4, 2, 7, 3, 6, 10. X NOTE: spacecraft is temporarily unable to function as a router.

5/22/2008 RMJ-7 Load/Go Deep ImpactDSOTDINET EOC in PTL stot EVRs “Earth” “Mars” “Phobos” Experiment database Load/Go bundles log msgs BRS TCP space links image files LTP/UDP serverclient serverclient serverclient Experiment 4: manually route traffic between nodes 12 and 20 (both remote) via the orbiter, without Earth in the loop from node 20 to 12 and 12 to 20.

5/22/2008 RMJ-8 The DINET Stack UT adapter TM/TC R/F, optical LTP BP DTN forwarding space packets AMS messaging Remote AMS compression Convergence layer adapter CFDP File Data PDUs ( “Protocol X”) Image publisher/receiver load/go rfx, admin programs, clocks

5/22/2008 RMJ-9 Interplanetary Overlay Network (ION) Reference implementation for the DTN Bundle Protocol (BP) is DTN2, maintained at UC Berkeley. –Designed as a research vehicle. –Widely used, well supported. Most DTN researchers are investigating terrestrial applications, for which DTN2 works very well. Space flight applications impose different constraints, motivating development of an alternative BP implementation for use in space flight missions. ION is an implementation of BP/LTP, developed at JPL, that’s designed to be usable in flight.

5/22/2008 RMJ-10 Constraints on a Flight Implementation Link constraints –All communications are wireless, generally slow, asymmetric. From spacecraft to ground: 256 Kbps to 6 Mbps. From ground to spacecraft: 1 to 2 Kbps. –Links are very expensive, virtually always oversubscribed. –Fine-grained data delivery. Immediate delivery of partial data is often OK. Processor constraints –Flight processors typically run real-time operating systems (VxWorks®, RTEMS™) lacking protected memory models. –Robustness is paramount. No malloc and free or standard new and delete; must not crash other flight software. –Processing efficiency is important: Slow (radiation-hardened) processors. Relatively slow non-volatile storage: flash memory.

5/22/2008 RMJ-11 ION’s Divergence From DTN2 Design ElementDTN2IONRationale Language C++CProcessing efficiency, memory management visibility. Memory managementnew, deletePSMNo dynamic system memory management permitted. Non-volatile storage management Berkeley DB, RDBMS (MySQL) SDR persistent objects Processing efficiency, footprint. Locus of processingdtnd daemon process, separate routing engine highly distributed: forwarders, ducts, applications, and admin tools Robustness (module simplicity, incremental upgrade; prevent head- of-line blocking); simplify flow control. Locus of node state (e.g., queues) private memory of dtnd daemon shared memorySupport distributed functionality, limit impact of demand spikes. Application Programming Interface remote procedure calls to dtnd shared library functions act on shared memory Support real-time operations: prevent blocking, support deterministic execution. Endpoint IDs in bundle’s primary block only ASCII URIs in dictionary supports CBHEBandwidth efficiency.

5/22/2008 RMJ-12 Performance ION flight software footprint: about 708 kilobytes including SDR database management system.

5/22/2008 RMJ-13 Contact Graph Routing #***************************************************************************** # #** DINET experiment pass #1. Monday morning, October 20. ** 2008/10/20-11:00:00 a range a range a range # # Contact between nodes 5 and 7 for a contact a contact # # Contact between nodes 3 and 7 for a contact a contact # # Contact between nodes 2 and 7 for a contact a contact #

5/22/2008 RMJ-14 Status of ION Conforms to version 6 of the BP specification (June 2007). Single code base runs without modification in all environments. So far: –Red Hat Linux 8+, Ubuntu Linux on 32-bit processors. –Fedora Core 3+, on 32-bit and 64-bit processors. –VxWorks 5.4 on PowerPC 750. –Mac OS/X Interoperability with DTN2 (and other Bundle Protocol implementations: C#,.Net, Symbian) demonstrated at IETF in San Diego, November 2006.

5/22/2008 RMJ-15 DINET Instrumentation Protocol status, diagnostic, and statistics messages issued by every node, including the spacecraft. Current network topology and running logs of messages displayed on the operations console in the Experiment Operations Center. Detailed “watch” character stream of event indications can be selectively enabled and disabled in real time at each node.

5/22/2008 RMJ-16 Key Metrics Metric 1 – Link Utilization Rate Metric 2 – Delivery Acceleration ratio Metric 3 – ION Node Storage Utilization Metric 4 – Multipath Advantage Priority X Dynamic Routing X Automated ForwardingX Custody TransferX X Delay-Tolerant RetransmissionX Flow & Congestion ControlX X Link Utilization Delivery Acceleration Ratio ION Node Storage Utilization Multipath Advantage Applicability to DTN Features

5/22/2008 RMJ-17 DTN Validation Criteria Metric 1 – Path utilization rate (U) –U = R T /K, where R T is total volume of science data returned and K is the total data return capacity (adjusted per artificially induced segment loss as applicable). –Measures the effectiveness of automatic forwarding, custody transfer, and delay- tolerant retransmission. –Validation criteria: U a > 90%. (DTN uses the links efficiently when there is no induced data loss.) U b > 90%. (DTN remains efficient despite an increase in the rate of data loss.) Metric 2 – Delivery acceleration ratio (G) –W = (.5 *) + (1.0 * R 1 ) + (2.0 * R 2 ), where W is the urgency-weighted volume of science data returned and R 0, R 1, and R 2 are respectively the total volumes of priority-zero, priority-1, and priority-2 science data returned. (Note that R T = R 0 + R 1 + R 2.) –Q 0 =.25 * R T where Q 0 is the “ reference ” volume of priority-zero science data returned, so computed because we will arbitrarily assign priority zero to 25% of all DINET science data. Similarly, Q 1 =.60 * R T and Q 2 =.15 * R T. –V = (.5 * Q 0 ) + (1.0 * Q 1 ) + (2.0 * Q 2 ), where W is the urgency-weighted reference volume of science data returned. –G = W / V. –Measures the effectiveness of the priority system. –Validation criteria: G a > 1. (Prioritization accelerates the delivery of urgent data.) G b > 1.

5/22/2008 RMJ-18 DTN Validation Criteria (Continued) Metric 3 – ION node storage utilization –Retention of a stable margin of unassigned space at each node measures the effectiveness of congestion control. –Validation criteria: The total number of bundles for which custody is refused anywhere in the network for the reason Depleted Storage, throughout each experiment, is always zero. (Never run out of storage anywhere.) N X4 = N X3 and N X8 = N X7 for all values of X. (Storage utilization stabilizes over the course of the experiment.) Metric 4 – Multipath advantage –The net path capacity P XYa for any single path from node X to node Y during configuration a is the smallest value of ∑K ABZ for Z = 1  4 among all links (A, B) in that path; P XYb is similarly defined for configuration b. –The multipath advantage M XYa for traffic from X to Y during configuration a is computed as ∑P XYa for all paths from X to Y, divided by the largest single P XYa among all paths from X to Y, minus 1. –Where there is only a single possible path between X and Y, multipath advantage is zero. Multipath advantage measures the effectiveness of dynamic routing. –Validation criteria: M XYa > 0 for X = node 20 and Y = node 8. (Dynamic routing among multiple possible paths increases the total network capacity from Phobos to Earth.) M XYb > 0 for X = node 20 and Y = node 8..

5/22/2008 RMJ-19 Environment Envelope Given or measured quantities that will be reported as part of the experiment These are the primary mission parameters and initial conditions that affect the performance results for a given DTN implementation. Environment Envelope –Propagation Delay - 2min –Partition Delay - 5 day (contact latency - network is partitioned) –File Size - Range is 2-65KB Maximum size message with AMS is 65KB For images larger than 65KB, a mission should use CFDP in conjunction with AMS and BP but this is not part of our experiment since simple unacknowledged CFDP has been implemented previously. –Data Rates ( ,000 bps) –Number of end nodes (11) –Number of links per node –total number of links –Contact duration (4 hours) –Data volume –Data Completeness –Data Quality –Bit Error Rate –Available buffer size

5/22/2008 RMJ-20 DTN Protocol Envelope

5/22/2008 RMJ-21 Project schedule Critical path runs through the ION/DIAS testing on EPOXI test beds There are 17 days of funded project schedule reserve