xiphos.ca charlie younghusband xiplink product manager xiphos technologies xiphos’ work with...
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xiphos.ca
Charlie Younghusband
XipLink Product Manager
Xiphos Technologies
Xiphos’ Work with SCPS-TP & applications and interest in CisLunar
Introducing XipLink
xiphos.ca
About Xiphos and XipLink
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 driverRobust basis
Incorporated in 1996
xiphos.ca
Quick History
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
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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
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SCPS-TP
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
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SCPS-TP
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
xiphos.ca
SCPS-TP Activities
Selling our own “XipLink Gateways” installed bracketting satellite links
Licensed into vendor satellite terminals Specialized projects in defence Used for end-point communication to on-
board spacecraft nodes
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Xiphos SCPS-TP
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
xiphos.ca
Related Projects I
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.
xiphos.ca
Related Projects II
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
xiphos.ca
SCPS-TP to CisLunar
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
Charlie Younghusband
XipLink Product Manager
514-848-9640 x221
#800 - 3981 St. Laurent Blvd.
Montreal, Quebec, Canada
http://www.xiplink.com/
IP Communications through stressed links.