04th Aprils 2008

© Skysoft, 2006

SaSatellitetellite NNetworketwork TTransportransportAArchitecturerchitecture

SaNTASaNTA

Catarina Almeida Catarina Almeida –– Project Project ManagerManager

AndrAndréé Rosado Rosado –– SW SW EngineerEngineer

2

SKYSOFT PORTUGAL

• Software & Systems Engineering Company

• Founded in 1998

• Based in Lisboa

• Turnover expected 2008: ≈ 6.5 M€

• Human Resources: ≈ 90 Eng.

Leading Portuguese Supplier of the European Space Agency (ESA)

Leading Portuguese Company in Software Engineering for Civil Aviation

Reference Portuguese Company for European Commission (EC)

3

SKYSOFT BUSINESS MODEL

• Outstanding System & Software Engineering• R&D Partnerships • Institutional Space & Defence Markets• Strong Customer Focus• Engineering Solutions and Applications

OPERATIONAL AREAS

A) Aeronautics, Aerospace, Security & Defence:Safety Critical SoftwareIntegrated Modular AvionicsIntegrated Security SystemsAir Traffic Management SystemDefence Data Networks & Systems

• Satellite Navigation• Ground Segment (PDS, SCC) • Satellite Communications Systems• Link 11 / Link 16 Data Translator• Maritime Surveillance

• AIS, VTS, SAR Integration

B) Telematics & Business Solutions:Intelligent Transport SystemsMobility (LBS, GIS, FM) IT & Business Solutions

MobilitySecurityIntelligent Transport Systems Surveillance

Market Applications

Technologies Mastering

GALILEO GMESPASR…

Aero-Space & Defence

SatComAvionicsNavigationMaritime…

Key Contribution Infrastructure& Institutional Programmes

4

SaNTA EntitiesESA is the main stakeholder of the SaNTA project

Skysoft is the Prime Contractor of the SaNTA project;

IT was the Subcontractor of the SaNTA project;

Satellite Network Transport Architecture

5

SaNTA aims to cover 2 main problems related to satellite communication networks:

The low performance of TCP - providing an efficient exploitation of TCP traffic over long-latency satellite links, which are typically limited by congestion control mechanism. Breaks the traditional end-to-end paradigm by using a split architecture where intermediate nodes impersonate end nodes for accelerating TCP acknowledges;

Bandwith Link Capacity - Manager link capacity allocated and (de)allocate bandwidth to a user by increasing or decreasing traffic generated and manage bandwidth and services information between layers.

SaNTA Framework Overview

6

SaNTA Prototype Test-Bed:• SaNTA Performance covered by a well defined and implemented

Test-Bed scenarios;

• Test-Bed scenarios support both Emulated (Dummynet Tool) andReal satellite Link. Two Types of Trials carried:• Laboratory Trials: Carried out in Skysoft premises• On-Site Trials: Carried out in Skysoft and GMV (Antenas) premises

• Analysis Tools: The trials exercised SaNTA’s services and mechanisms to wrap measurements where the concept proves its viability and performance gains of the proposed technology in satellite communications.

SaNTA Framework Approach

7

SaNTA Development Phases Phase I: TPRMMSN• Concept Developed and Implemented

Phase II: SaNTA• Test-bed definition and implemented in laboratory

Phase III: SaNTA Sec• Security Features developed and implemented

Phase IV: SaNTA AmerHis (current phase)• Test-Bed definition and implemented in a Real Satellite System (DVB-RCS)

SaNTA User ApplicationsData transmission over satellite:• WEB browsing (HTTP) • remote login (TELNET) • e-mail • file transfers (FTP)

SaNTA Development Phases

8

PROTOTYPEPROTOTYPE

SaNTA Future Intentions...

PRODUCTPRODUCT

9

SaNTA AmerHis Demosntration – Achievements and Objectives

SaNTA AmerHis Achievements and Objectives

To be presented by André Rosado

10

SaNTA AmerHis System

PurposeExtensively test SaNTA prototype in a DVB-RCS environment

MotivationAssess performance with a consolidated standard in the segmentCompare results against TCP implementation

André Rosado

11

SaNTA AmerHis – Network Setup

RCST and IWU machines were placed at Madrid due to regulatory issues (frequency band) in Portugal regarding AmerHis Antennas

12

SaNTA AmerHis – SaNTA Framework (I)

SaNTA Protocol Stack

13

SaNTA AmerHis – SaNTA Framework (II)

Developed ProtocolsITLSaSTP

Network Elements present in the architectureSatellite Enhancer (SE) SE acts as a gateway between normal TCP traffic, used by user applications and servers, and ITL traffic managed by SaNTA. The SE is located at a point where the LAN traffic enters or exits the associated WAN. Thus all the LAN traffic passes through it

Interworking Unit (IWU) IWU is the common termination point for both a terrestrial transport segment and a satellite transport segment, effectively acting as a transport protocol converter between the two segments.

14

SaNTA AmerHis – AmerHis

HISPASAT HISPASAT -- AmerHis SystemAmerHis System

Multimedia payload embarked in a commercial communication satellite system

Regenerative System

Support of open standards DVB-RCS/DVB-S

Meshed Topology

Dynamic management of bandwidth – DAMA protocol, with capacity categories CRA and RBDC

15

SaNTA AmerHis – Network Setup

RCST and IWU machines were placed at Madrid due to regulatory issues (frequency band) in Portugal regarding AmerHis Antennas

16

Test Cases DefinitionHeavy-load conditionsLight-load conditionsDifferent levels of BER Different satellite link ratesDifferent DAMA parametersWeb Page Load

Tests performed using SaNTA architecture, followed by similar measures made with TCP

SaNTA AmerHis – Test Plan

17

Comparation against TCP for Peak Data Rate = 2 Mbps

For larger objects, end-to-end transfer delay of SaNTA is ~ 40 % lower than TCP

0

20

40

60

80

100

120

0 200000 400000 600000 800000 1000000 1200000Object Size (bytes)

Tran

sfer

Tim

e (s

ec)

SaNTA End-to-End TCP Linear (SaNTA) Linear (End-to-End TCP)

SaNTA AmerHis – Main Results (I)

18

Comparation against TCP for Heavy-load conditions (20 Mb evenly distributed)

Fairness achieved for SaNTA (Average Throughput ~ 300 Kbps)

SaNTA AmerHis – Main Results (II)

0,00

50,00

100,00

150,00

200,00

250,00

300,00

350,00

1 connection 2 connections 5 connections

Number of simultaneous connections

Avg

Data

Tra

nsfe

r Rat

e (K

bps)

SaNTA TCP

19

••Comparation against TCP with BER (=1.5*10eComparation against TCP with BER (=1.5*10e--6)6)SaNTA measures correspond to an average data rate three times faster than TCP

0

20

40

60

80

100

120

140

0 200000 400000 600000 800000 1000000 1200000

Object Size (bytes)

Tran

sfer

Tim

e (s

ec)

SaNTA End-to-End TCP Linear (SaNTA) Linear (End-to-End TCP)

SaNTA AmerHis – Main Results (III)

20

Comparation between SaNTA measures for different Comparation between SaNTA measures for different BER valuesBER values

Performance only begins to suffer for BER around 5*10e-6, with data rate decreasing 25%

0

20

40

60

80

100

120

140

160

180

0 200000 400000 600000 800000 1000000 1200000

Object Size (bytes)

Tran

sfer

Tim

e (s

ec)

BER:3*10e-8 BER:1.5*10e-6 BER:5*10e-6 BER:1.6*10e-5

Linear (BER:3*10e-8) Linear (BER:1.5*10e-6) Linear (BER:5*10e-6) Linear (BER:1.6*10e-5)

SaNTA AmerHis – Main Results (IV)

21

05

10152025303540

BER=0

BER=1

E-6,

PER=~

1.1%

BER=5

E-6,

PER=~

5.5%

BER=1

E-5,

PER=~

10.8%

BER=2

E-5,

PER=~

20.4%

KByt

es/s

End2End TCPSaNTA

Comparation between SaNTA and TCP for different Comparation between SaNTA and TCP for different BER values BER values (for TCP measures, values were extrapolated from (for TCP measures, values were extrapolated from laboratory tests)laboratory tests)

SaNTA AmerHis – Main Results (V)

22

Comparation against TCP with modification of SDR Comparation against TCP with modification of SDR parameter (in chart below, SDR=0, no CRA assigned)parameter (in chart below, SDR=0, no CRA assigned)

Performance on both architectures suffer in terms of response time, but SaNTA maintains its average data rate for larger transfers

0

20

40

60

80

100

120

140

160

180

200

220

240

260

0 200000 400000 600000 800000 1000000 1200000

Object Size (bytes)

Tran

sfer

Tim

e (s

ec)

SaNTA End-to-End TCP Linear (SaNTA) Linear (End-to-End TCP)

SaNTA AmerHis – Main Results (VI)

23

•SaNTA AmerHis – Main Results (VI)

Comparation between SaNTA trials with modification of Comparation between SaNTA trials with modification of SDR parameter (SDR=0,20 and 200 Kbps)SDR parameter (SDR=0,20 and 200 Kbps)

Similar behaviour (parallel graphs), with SaNTA response to smaller transfers being directly determined by SDR value

0

10

20

30

40

50

60

70

0 200000 400000 600000 800000 1000000 1200000 1400000 1600000 1800000 2000000

Object Size (bytes)

Tran

sfer

Tim

e (s

ec)

Test E1 (SDR=0 Kbps) Test E2 (SDR=20 Kbps) Test E3 (SDR = 200 Kbps)Linear (Test E1 (SDR=0 Kbps)) Linear (Test E2 (SDR=20 Kbps)) Linear (Test E3 (SDR = 200 Kbps))

24

SaNTA architecture tested under the AmerHis System, with the purpose of assessing performance and compare against End-to-End TCP similar measures

SaNTA proved to be a more efficient implementation under the following conditions:

Heavy Load ConditionsHigh BER value on Satellite linkDifferent AmerHis configurations, varying values of SDR and PDR

SaNTA has a considerably higher throughput than TCP.

Evidence of the fairness mechanism implemented in SaNTA.

SaNTA AmerHis Conclusions

25

More efficient use of satellite link resourcesLess sensitive to variation of bandwidthNo slow start

Provides stability and fairness in the multiplexing of end-to-end data-flows

SaNTA Advantages over End-to-End TCP

26

SaNTA supports end-to-end security in ITL layerPEP is incompatible with end-to-end IP sec

SaNTA preserves end-to-end contextPEP breaks end-to-end context

IWU is an explicit network elementPEP is a proxy

SaNTA Advantages over PEP

27

SaNTA AmerHis Rersults – Open Discussion

28

SaNTA performance consistently better than TCP in all SaNTA performance consistently better than TCP in all scenarios consideredscenarios considered

Fairness between connections is achieved Fairness between connections is achieved

Obtained results for SaNTA architecture confirm expectations Obtained results for SaNTA architecture confirm expectations based on previous laboratory testsbased on previous laboratory tests

AmerHis System allowed tests modifying DVBAmerHis System allowed tests modifying DVB--RCS parameters, RCS parameters, increasing knowledge on SaNTA performance increasing knowledge on SaNTA performance

SaNTA Conclusions

29

QUESTIONS AND ANSWERS

30

SaNTA AmerHis

THANKS FOR YOUR PRESENCETHANKS FOR YOUR PRESENCE

More information of SaNTA in

www.skysoft.pt

Catarina Almeidacatarina.almeida@skysoft.pt