1. xiphos.ca Charlie Younghusband XipLink Product Manager Xiphos Technologies Xiphos’ Work with SCPS-TP & applications and interest in CisLunar Introducing XipLink

2. xiphos.ca About Xiphos and XipLink l Relatively small engineering company located in Montreal, Quebec ä > ~80% of employees with a minimum Bachelors in Engineering in various disciplines l Research & Development: Aerospace applications is the primary technology driver ä Robust basis l Incorporated in 1996

3. xiphos.ca Quick History l Involved in a telehealth project moving large data files over satellite and ran into TCP over satellite issues ä Did tuning ä Developed our own TCP->UDP transport protocol using the framework of another technology we had l Independently, we had looked at SCPS for some onboard work, did a limited SCPS-NP implementation l Approached and received partial funding from the CSA for a high performance implementation of SCPS-TP in 2000

4. xiphos.ca Xiphos SCPS-TP -> XipLink Implementation of SCPS-TP became basis for XipLink – “link performance enhancement technology for stressed communication links” Integrates other optimizations like data compression and HTTP Acceleration Can meet or beat all competition SCPS’ design is very practical to directly scale terrestrial communications to satcom and space SCPS-TP implementation implemented differently than RI. Does T/TCP, does not do Best Effort Transport Service (BETS). More optimized for Satcom

5. xiphos.ca SCPS-TP l Uses sender side only algorithms or negotiates capabilities (extensions to normal TCP) through TCP options at connection setup l Can go end-to-end or a proxy gateway architecture l Very flexible architecture. Easy to change, can be done adhoc or ‘mixed’, legacy network deployment benefits ä Big reason for its adoption by US Military l Flexible for integrating other technologies from Internet or custom developed while maintaining architecture l Ease of analysis, IP transparency, when not using rate control can be QoS engineered

6. xiphos.ca SCPS-TP l Sending congestion control ä Rate control: bandwidth known ä TCP Vegas: variable, shared links l Selective Negative Acknowledgments (SNACK) more responsive and efficient l TCP Header Compression: removes redundancy l TCP for Transactions: skips 3 way handshake l ACK frequency reduction to limit return path bandwidth

7. xiphos.ca SCPS-TP Activities l Selling our own “XipLink Gateways” installed bracketting satellite links l Licensed into vendor satellite terminals l Specialized projects in defence l Used for end-point communication to on- board spacecraft nodes

8. xiphos.ca Xiphos SCPS-TP l Used BSD Network stack as a basis l Low level implementation in kernel on Linux and VxWorks well l Many optimizations for dynamic buffering, managing 10,000 connections+, burst connection opens, really advanced rate control algorithm, QoS options

9. xiphos.ca Related Projects I l Dynamic bandwidth satellite terminals strong focus for maximizing bandwidth utilization and distribution among many nodes l Many ways of managing access to the link l Side channel requests, dedicated slots, ALOHA etc. l DVB-RCS (Return Channel via Satellite) is a standard growing in recognition l The general ‘volume’ based capacity allocation results in ~1.5 second RTT. Design expecting 1.8 seconds. Increased load can increase this. l Going through standardization right now.

10. xiphos.ca Related Projects II l Doing our own project via SCPS-TP to UAV ä Do it in combination with UDP telemetry data streams l Other projects by US Primes for aircraft communications ä Choice or varying communication links, paths l Possibly more than one satcom hop also high delay, possible high BER l SCPS-TP will fly on a microsatellite launching in June

11. xiphos.ca SCPS-TP to CisLunar l Many of the same issues. l IP/SCPS-TP could used but could really use updates l Other SCPS layers future doubtful l Evaluation of necessary extensions, IPV6 etc l We will be looking at other complementary environments like DVB-RCS – session layer/inter gateway communication l Further published study work

12. xiphos.ca Charlie Younghusband XipLink Product Manager cwy@xiphos.ca 514-848-9640 x221 #800 - 3981 St. Laurent Blvd. Montreal, Quebec, Canada http://www.xiplink.com/ IP Communications through stressed links.