Deep Space Network Emulation

1. 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. Introduction • Presentation Outline • Motivation • Application • Definition • Overview • Design • Configuration • Testing & Results • Conclusions

3. 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. 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. 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. } User } Emulator 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

7. 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. 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. 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. 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. 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. Thank You • Thank You for Your Time and Attention • Any Questions?

13. 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. Additional Slides • Additional Slides Begin Here

15. 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. 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. Results (1 of 2) • Worst Case Delay

18. Results (2 of 2) • Average Case Delay • Bit Error Rate