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Introducing XipLink xiphos.ca Xiphos’ Work with SCPS-TP & applications and interest in CisLunar Charlie Younghusband XipLink Product Manager Xiphos Technologies About Xiphos and XipLink xiphos.ca Relatively small engineering company located in Montreal, Quebec > ~80% of employees with a minimum Bachelors in Engineering in various disciplines Research & Development: Aerospace applications is the primary technology driver Robust basis Incorporated in 1996 Quick History xiphos.ca Involved in a telehealth project moving large data files over satellite and ran into TCP over satellite issues Did tuning Developed our own TCP->UDP transport protocol using the framework of another technology we had Independently, we had looked at SCPS for some onboard work, did a limited SCPS-NP implementation Approached and received partial funding from the CSA for a high performance implementation of SCPS-TP in 2000 Xiphos SCPS-TP -> XipLink xiphos.ca • • • 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 SCPS-TP xiphos.ca Uses sender side only algorithms or negotiates capabilities (extensions to normal TCP) through TCP options at connection setup Can go end-to-end or a proxy gateway architecture Very flexible architecture. Easy to change, can be done adhoc or ‘mixed’, legacy network deployment benefits Big reason for its adoption by US Military Flexible for integrating other technologies from Internet or custom developed while maintaining architecture Ease of analysis, IP transparency, when not using rate control can be QoS engineered SCPS-TP xiphos.ca Sending congestion control Rate control: bandwidth known TCP Vegas: variable, shared links Selective Negative Acknowledgments (SNACK) more responsive and efficient TCP Header Compression: removes redundancy TCP for Transactions: skips 3 way handshake ACK frequency reduction to limit return path bandwidth SCPS-TP Activities xiphos.ca Selling our own “XipLink Gateways” installed bracketting satellite links Licensed into vendor satellite terminals Specialized projects in defence Used for end-point communication to onboard spacecraft nodes Xiphos SCPS-TP xiphos.ca Used BSD Network stack as a basis Low level implementation in kernel on Linux and VxWorks well Many optimizations for dynamic buffering, managing 10,000 connections+, burst connection opens, really advanced rate control algorithm, QoS options Related Projects I xiphos.ca Dynamic bandwidth satellite terminals strong focus for maximizing bandwidth utilization and distribution among many nodes Many ways of managing access to the link Side channel requests, dedicated slots, ALOHA etc. DVB-RCS (Return Channel via Satellite) is a standard growing in recognition The general ‘volume’ based capacity allocation results in ~1.5 second RTT. Design expecting 1.8 seconds. Increased load can increase this. Going through standardization right now. Related Projects II xiphos.ca Doing our own project via SCPS-TP to UAV Do it in combination with UDP telemetry data streams Other projects by US Primes for aircraft communications Choice or varying communication links, paths Possibly more than one satcom hop also high delay, possible high BER SCPS-TP will fly on a microsatellite launching in June SCPS-TP to CisLunar xiphos.ca Many of the same issues. IP/SCPS-TP could used but could really use updates Other SCPS layers future doubtful Evaluation of necessary extensions, IPV6 etc We will be looking at other complementary environments like DVB-RCS – session layer/inter gateway communication Further published study work xiphos.ca xiphos.ca IP Communications through stressed links. Charlie Younghusband XipLink Product Manager [email protected] 514-848-9640 x221 #800 - 3981 St. Laurent Blvd. Montreal, Quebec, Canada http://www.xiplink.com/