Download Xyphos Xiplink SCPS-TP and Cislunar Comms

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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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/