Competence Center for Advanced Network Technologies and Systems

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Competence Center for Advanced Network Technologies and Systems TCP/IP Over LEO Satellites Related Activities

Competence Center for Advanced Network Technologies and Systems TCP/IP Over LEO Satellites Related Activities within the ATM-Sat Project Presentation to Industry Representatives and Interested Scientists http: //www. fokus. gmd. de/cats Marc Emmelmann

Contents n Test- & Measurement Suite n n Global Set-Up Probe Station Simulation Environment

Contents n Test- & Measurement Suite n n Global Set-Up Probe Station Simulation Environment First Simulation Results 2000 -12 -12 Marc Emmelmann 2

Global Set-Up Satellite Channel Emulation Probe Station Satellite Modem ATM-Sat Demonstrator Hardware 2000 -12

Global Set-Up Satellite Channel Emulation Probe Station Satellite Modem ATM-Sat Demonstrator Hardware 2000 -12 -12 Probe Station Marc Emmelmann 3

Probe Station n Consists of: n Workstation or PC running standard operating system Free.

Probe Station n Consists of: n Workstation or PC running standard operating system Free. BSD y Windows y further OS possible y n n Protocol & performance testing tools (RFC 2398) Used as: n n TCP analyzer User application platform 2000 -12 -12 Marc Emmelmann 4

TCP Analyzer n Fundamental Performance Evaluation n n Pre-defined set of experiments Automatic execution

TCP Analyzer n Fundamental Performance Evaluation n n Pre-defined set of experiments Automatic execution Base for comparing TCP flavors and network effects Configuration: n n Operation System: Free. BSD 4. 1 Testing Tools: DBS, netperf, . . . 2000 -12 -12 Marc Emmelmann 5

User Application Platform n Subjective Qo. S n n Set of “daily life” applications

User Application Platform n Subjective Qo. S n n Set of “daily life” applications User interaction Supplementary performance evaluation Configuration: n n n Operation System: Windows, Unix, . . . Applications: Web-Browsing, NFS, etc. Supplementary Tools: tcptrace, tcpdump, . . . 2000 -12 -12 Marc Emmelmann 6

Where We Are. . . n n Test- & Measurement Suite Simulation Environment n

Where We Are. . . n n Test- & Measurement Suite Simulation Environment n n n General Aspects System Parameter First Simulation Results 2000 -12 -12 Marc Emmelmann 7

General Aspects n Independence of demonstrator hardware n n n Availabiltity only within final

General Aspects n Independence of demonstrator hardware n n n Availabiltity only within final phase Isolate demonstrator (hardware) specifc side effects Unknown flavors of TCP Analysis of “large” networks Adaptation to emerging project constrains Simulation tool: OPNET modeler / radio n n Industry prooven ATM support Satellite Orbits can be included Project specific aspects 2000 -12 -12 Marc Emmelmann 8

System Parameters n n n Satellite Orbit Bit Rates Bit Error Rate Up- &

System Parameters n n n Satellite Orbit Bit Rates Bit Error Rate Up- & Down-Link Delay Intra-Satellite Delay End-to-End Delay 2000 -12 -12 Marc Emmelmann 9

Satellite Orbit n Slant Range n n Analytical model Function of orbit altitude Visibility

Satellite Orbit n Slant Range n n Analytical model Function of orbit altitude Visibility constrains Analytical vs. Simulated Distance n n STK based simulation compared to theroy derivation less than 2% 2000 -12 -12 Marc Emmelmann 10

Bit Rates ISL: 7 - 10 Gbit/s Service Uplink (fixed): 2. 048 Mbit/s Feeder

Bit Rates ISL: 7 - 10 Gbit/s Service Uplink (fixed): 2. 048 Mbit/s Feeder Up & Downlink: 32. 768 Mbit/s Service Uplink (portable): 384 kbit/s Service Downlink: 32. 768 Mbit/s 2000 -12 -12 Marc Emmelmann 11

Bit Error Rate n n BER at target system above MAC Up- & Down-Link

Bit Error Rate n n BER at target system above MAC Up- & Down-Link n n Good weather condition: 2*10 E-8 Rain causes link to collaps y last for approx. 10 minutes y n n n “on-off” modell ISLs Limitations 2000 -12 -12 Marc Emmelmann 12

Up- & Down-Link Delay n n Based upon analytically gained distance Comparison analytical vs.

Up- & Down-Link Delay n n Based upon analytically gained distance Comparison analytical vs. simulated delay 2000 -12 -12 Marc Emmelmann 13

Intra-Satellite Delay n n Final “routes in the sky” still open Assumed ISLs: n

Intra-Satellite Delay n n Final “routes in the sky” still open Assumed ISLs: n n n To forward and backward satellite To left and right neighbor Simulation based delays 2000 -12 -12 Marc Emmelmann 14

End-to-End Delay n Describes aspects of: n n n Routing behavior “in the sky”

End-to-End Delay n Describes aspects of: n n n Routing behavior “in the sky” Intercontinental connections Cooperate networks Currently not considered Obtained through final simulations Reference measurements predict approx 150 ms 2000 -12 -12 Marc Emmelmann 15

Where We Are. . . n n n Test- & Measurement Suite Simulation Environment

Where We Are. . . n n n Test- & Measurement Suite Simulation Environment First Simulation Results n n Link Model Description Link Model Verification RTT Measurement of TCP Future Steps 2000 -12 -12 Marc Emmelmann 16

Link Model Description n Link: n n Delay n n n Point-to-point Symmetrical or

Link Model Description n Link: n n Delay n n n Point-to-point Symmetrical or asymmetrical Wired Function of time Deterministic, periodical Configurable Parameter: n n BER Bit rate 2000 -12 -12 Marc Emmelmann 17

Link Model Verification n Delay: Expected values y Consider queuing delay y n Bit

Link Model Verification n Delay: Expected values y Consider queuing delay y n Bit rate y Upper Limit 2000 -12 -12 Marc Emmelmann 18

RTT Measurement of TCP n Impact of RTT-gain coefficient n n Acts as „smoothing“

RTT Measurement of TCP n Impact of RTT-gain coefficient n n Acts as „smoothing“ factor Considered values gain = 0. 125 y gain = 1 y n Results n n Derivation less than 1 ms „Smoothed“ curved closer to real round-trip delay variation 2000 -12 -12 Marc Emmelmann 19

Future Steps n n n Timer granularity Effects of variable delay on throughput Switch

Future Steps n n n Timer granularity Effects of variable delay on throughput Switch to wireless link model Better BER model Simulation of “large” networks Include ATM-Sat MAC 2000 -12 -12 Marc Emmelmann 20

World Wide Web n http: //www. fokus. gmd. de y n http: //www. fokus.

World Wide Web n http: //www. fokus. gmd. de y n http: //www. fokus. gmd. de/cats y n Information about the Competence Center CATS http: //www. fokus. gmd. de/cats/projects y n Information about FOKUS Information about the project http: //www. fokus. gmd. de/cats/publ Download this presentation y Other CATS publications y 2000 -12 -12 Marc Emmelmann 21

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