1. Glenn Research Center at Lewis Field Deep Space Network Emulation Shaun Endres and Behnam Malakooti Case Western Reserve University Department of Electrical Engineering and Computer Science {Shaun.Endres, Behnam.Malakooti}@case.edu Kul Bhasin and Allen Holtz NASA Glenn Research Center Space Communications {Kul.B.Bhasin, Allen.P.Holtz}@grc.nasa.gov

2. Glenn Research Center at Lewis Field Introduction Presentation Outline Motivation Application Definition Overview Design Configuration Testing & Results Conclusions

3. Glenn Research Center at Lewis Field Motivation Network Analysis Motivation Performance assessment Risk assessment Deep Space Emulation Motivation No known tools for evaluating deep space networks –Space Based Internet Emulator (University of Kansas) –The Network Simulator (ns-2) Active Networking

4. Glenn Research Center at Lewis Field Application Deep Space Network Nodes (Earth, Moon, Mars, and beyond) Ground stations Satellites Space shuttles Anything that the Satellite Tool Kit (STK) can handle Researchable Issues Protocols Routing algorithms Communication architectures

5. Glenn Research Center at Lewis Field Network Emulation Definition Emulation refers to the ability to introduce a simulator into a live network. Comparison Simulation is _____ than emulation –Less Expensive –Faster (depending on the complexity) –Less Accurate A real hardware test-bed is _____ than emulation –Significantly more expensive –More accurate –Less controllable

6. Glenn Research Center at Lewis Field Emulator Overview Emulator Features Completely in user space Any network, transport, or application layer protocol possible Strict cutoff between emulator and user Emulator Usage Emulator is transparent to the end user } User } Emulator

7. Glenn Research Center at Lewis Field Emulator Design (Control & Emulation Network) Control Network Star Topology Sends ‘Physical’ Information TCP/IP Used Link Always Available Error Free Link Emulation Network Fully Connected Network Sends ‘Networking’ Information Researched Protocol Used Link Availability Based on ‘Physical’ Information Error Prone Link

8. Glenn Research Center at Lewis Field Emulator Design (Information Flow) Control Network Communicates with STK [7] to determine position and link information Updates all nodes’ link tables periodically Emulation Network Applies information contained in link tables to all out going packets Physical and Data Link Layers Modeled within the emulator code Network, Transport, and Application Layers Actual implementation (left up to the researcher to implement)

9. Glenn Research Center at Lewis Field Emulator (Physical Setup) Hardware Cisco Catalyst 2900 series XL switch Intel Pentium III 600MHz processor computer with 128MB of RAM Fast Ethernet Software STK 5.0.4 Microsoft Windows XP Professional Microsoft Visual Studio.NET 2002 Programming Language C#

10. Glenn Research Center at Lewis Field Results Delay Verification Delay Accuracy gets better as the delay increases With a 30s delay, there is about a 0.1% error Bit Error Rate Verification Bit error rate application has about a 0.25% error

11. Glenn Research Center at Lewis Field Conclusions and Future Work Conclusions Deep Space Network Emulation is Possible Without Kernel Modifications Great Flexibility Can Be Given to the User OS Interrupt Timer Is Limiting Factor Future Work Multiple Nodes Bandwidth Restriction Deep Space Mission Scenario Analysis Protocol Testing for Deep Space Missions

12. Glenn Research Center at Lewis Field Thank You Thank You for Your Time and Attention Any Questions?

13. Glenn Research Center at Lewis Field Selected References [1] http://www.isi.edu/nsnam/ns/ns-emulation.html [2] Bateman, M., Allison, C., and Ruddle, A., “A Scenario Driven Emulator for Wireless, Fixed and Ad Hoc Networks,” 2003. [3] Zheng, P., and Ni, L. M., “EMPOWER: A Network Emulator for Wireline and Wireless Networks,” IEEE INFOCOM, 2003. [4] Zheng, P., and Ni, L. M., “EMPOWER: A Scalable Framework for Network Emulation.” [5] Zheng, P., and Ni, L. M., “Experiences in Building a Scalable Distributed Network Emulation System.” [6] Ingham, D. and Parrington, G., “Delayline: A Wide-Area Network Emulation Tool.” [7] www.stk.com [8] Rallapalli, S., “Emulation of a Space Based Internet Communication Link: Design and Implementation,” University of Kansas, 2000. [9] Baliga, S. R., “Design of a Space Based Internet Emulation System,” University of Kansas, 2002. [10] Endres, S., Griffith, M., Malakooti, B., Bhasin, K., and Holtz, A., “Space Based Internet Network Emulation for Deep Space Mission Applications,” AIAA ICSSC, May, 2004. [11] Sklar, B., “Digital Communications: Fundamentals and Applications,” Prentice Hall, 2001. [12] Herrscher, D., and Rothermel, K., “A Dynamic Scenario Emulation Tool.” [13] Carson, M., and Santay, D., “NIST Net – A Linux-based Network Emulation Tool.” [14] Yeom, I., and Reddy, A. L., “ENDE: An End-to-end Network Delay Emulator.” [15] Hu, Y., and Li, V. O. K., “Satellite-Based Internet: A Tutorial,” IEEE Communications Magazine, 2001.

14. Glenn Research Center at Lewis Field Additional Slides Additional Slides Begin Here

15. Glenn Research Center at Lewis Field Improvements to Existing Tools Improvements to the Space Based Internet Emulator Any transport and network layer protocol No kernel modifications Deep space objects Header errors Improvements to The Network Simulator (ns-2) Deep space objects Highly dynamic link changes

16. Glenn Research Center at Lewis Field Satellite Tool Kit (STK) Satellite Orbit Propagation Detailed satellite propagation Orbits around any planetary body Real time information STK/Connect can provide an application with real time information Link Budget Report STK/Communication can provide a detailed link budget report

17. Glenn Research Center at Lewis Field Results (1 of 2) Worst Case Delay MeasuredTargetDifferenceError 5.0067541.0067525.17% 10.013582.013525.17% 15.02025123.0202525.17% 15.02025160.979756.12% 15.02025204.9797524.90% 25.03375241.033754.31% 25.03375282.9662510.59% 35.04725323.047259.52% 35.04725360.952752.65% 35.04725404.9527512.38% 45.06075441.060752.41%

18. Glenn Research Center at Lewis Field Results (2 of 2) Average Case Delay Bit Error Rate MeasuredTargetDifferenceError 1100.00% 0.3171183330.3162280.0008910.28% 0.0997783330.10.0002220.22% 0.031810.0316230.0001870.59% 0.0100533330.015.33E-050.53% 0.0031316670.0031623.06E-050.97% MeasuredTargetDifferenceError 30030.493000030.48650.10% 30050.513000050.51350.17% 30035.493000035.493250.12% 30035.493000035.493250.12% 30020.473000020.4730.07% 30040.53000040.50.14% 30020.473000020.4730.07% 30015.473000015.466250.05% 30030.493000030.48650.10% 30035.493000035.493250.12%