implementation of ip mesh network using ule protocol over dvb-s links wan tat chee network research...

Implementation of IP Implementation of IP Mesh Network using ULE Mesh Network using ULE

Protocol over DVB-S Protocol over DVB-S LinksLinksWan Tat CheeWan Tat Chee

Network Research Group Network Research Group School Of Computer SciencesSchool Of Computer Sciences

Universiti Sains MalaysiaUniversiti Sains Malaysia 11800 USM, Penang, Malaysia.11800 USM, Penang, Malaysia.

[email protected]@cs.usm.my

April 12 April 12 (c) 2006 TC Wan(c) 2006 TC Wan 22

IntroductionIntroduction

Satellite-based Internet connectivitySatellite-based Internet connectivity• Provides access to rural / underserved Provides access to rural / underserved

communitiescommunities• Able to operate in areas without existing Able to operate in areas without existing

telecommunications infrastructuretelecommunications infrastructure• Quick setup for disaster relief and Quick setup for disaster relief and

recovery efforts (e.g., earthquakes, recovery efforts (e.g., earthquakes, tsunami, etc.)tsunami, etc.)


IssuesIssues Existing satellite-link based Internet access Existing satellite-link based Internet access

equipment is expensiveequipment is expensive Existing technology has inefficient spectrum Existing technology has inefficient spectrum

usageusage Existing hub-based network averages two hops Existing hub-based network averages two hops

among nodes (high latency)among nodes (high latency) DVB-S is a cost-effective method used in satellite DVB-S is a cost-effective method used in satellite

TV broadcast (e.g., Astro)TV broadcast (e.g., Astro) However, It is unidirectional in natureHowever, It is unidirectional in nature Unidirectional Link Mesh Network implements Unidirectional Link Mesh Network implements

bidirectional network access using DVB-S bidirectional network access using DVB-S technologytechnology


Existing Point-to-Point Existing Point-to-Point Satellite LinksSatellite Links


UniDirectional Link Mesh UniDirectional Link Mesh Networking ApproachNetworking Approach


Hardware RequirementsHardware Requirements

An ASI (Asynchronous Serial Interface) An ASI (Asynchronous Serial Interface) card to transmit MPEG2-TS packet (Linear card to transmit MPEG2-TS packet (Linear Systems’ DVB Master FD).Systems’ DVB Master FD).

(N – 1) DVB receiver cards where N is the (N – 1) DVB receiver cards where N is the number of nodes in the UDL mesh number of nodes in the UDL mesh network. List of supported DVB receiver network. List of supported DVB receiver cards: cards: http://www.linuxtv.org/wiki/index.php/DVB-http://www.linuxtv.org/wiki/index.php/DVB-S_cardsS_cards..

A DVB-S modulator (Newtec NTC2177).A DVB-S modulator (Newtec NTC2177).


Node Configuration Node Configuration (for 3-Node WAN network)(for 3-Node WAN network)


Configuration for 3 Nodes Test BedConfiguration for 3 Nodes Test Bed


Bidirectional DVB-S Bidirectional DVB-S ULE ArchitectureULE Architecture


Experiment and ResultExperiment and Result


Experiment and Result (cont)Experiment and Result (cont)Throughput for TCP Unicast v.s. TCP Window Size

0

200

400

600

800

1000

1200

1400

1600

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1 14 27 40 53 66 79 92 105 118 131 144 157 170 183 196

Time (s)

Th

rou

gh

pu

t (k

bp

s)

TCP WS216KBytes

TCP WS180KBytes

Log. (TCPWS216KBytes)

Log. (TCPWS180KBytes)


Experiment and Result (cont)Experiment and Result (cont)

Throughput Comparison for TCP Unicast on 8Mbps DVB-Mesh v.s. Benchmark on 10Mbps Wired LAN

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1000

2000

3000

4000

5000

6000

7000

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9000

10000

1 15 29 43 57 71 85 99 113 127 141 155 169 183 197

Time (s)

Th

rou

gh

pu

t(kb

ps)

Benchmark10Mbps WiredLAN TCP WS216KBytes

8Mbps UDL-Mesh TCP WS216KBytes

Log.(Benchmark10Mbps WiredLAN TCP WS216KBytes)Log. (8MbpsUDL-Mesh TCPWS216KBytes)


Experiment and Result (cont)Experiment and Result (cont)Throughput for UDP Unicast v.s. Offered Load

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1000

2000

3000

4000

5000

6000

7000

1 2 3 4 5 6 7 8 9

Time (s)

Th

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t (k

bp

s)

1Mbps

2Mbps

3Mbps

4Mbps

5Mbps

6Mbps

7Mbps

8Mbps



Average Packet Loss for UDP Unicast

1Mbps0%

2Mbps0%

3Mbps0%

4Mbps0.18%

5Mbps16%

6Mbps29%

7Mbps32%

8Mbps40%

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

Bandwidth Type

Pac

ket L

oss

(%)

1Mbps

2Mbps

3Mbps

4Mbps

5Mbps

6Mbps

7Mbps

8Mbps



Throughput Comparison for TCP Unicast and UDP Unicast

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1 13 25 37 49 61 73 85 97 109 121 133 145 157 169 181 193

Time (s)

Th

rou

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pu

t(k

bp

s)

TCP (WindowSize216KBytes)

UDP(Bandwidth4Mbps)

Log. (UDP(Bandwidth4Mbps))

Log. (TCP(Window Size216KBytes))


Analysis of ResultAnalysis of Result

All UDL nodes are allocated 8Mbps of All UDL nodes are allocated 8Mbps of bandwidth for the tests.bandwidth for the tests.

The throughputs of TCP and UDP traffic are The throughputs of TCP and UDP traffic are about 1/2 and 1/8 of allocated bandwidth about 1/2 and 1/8 of allocated bandwidth respectively.respectively.

ASI card buffer queue affects the latency ASI card buffer queue affects the latency of packet sending. Less buffer queue of packet sending. Less buffer queue decreases latency, but increases CPU decreases latency, but increases CPU usage due to more interrupts and context usage due to more interrupts and context switches.switches.


Analysis of Result (cont)Analysis of Result (cont)

Faulty ASI card firmware disables Faulty ASI card firmware disables automatic null packets insertion. Thus automatic null packets insertion. Thus bidirectional module need to insert null bidirectional module need to insert null packets manually.packets manually.

Consequently, real data packets have to Consequently, real data packets have to compete with null packets for resources. compete with null packets for resources. Thus the performance is less than ideal.Thus the performance is less than ideal.

Due to high latency, bigger TCP window Due to high latency, bigger TCP window size results in better throughput.size results in better throughput.


Future WorkFuture Work

Reimplemention of bidirectional Reimplemention of bidirectional module as a kernel space module to module as a kernel space module to cut the cost of context switches and cut the cost of context switches and improve performance.improve performance.

Try to obtain an ASI card that Try to obtain an ASI card that properly insert null packets properly insert null packets automatically.automatically.


Links & ContactsLinks & Contacts

IP over DVB-S via ULE research page: IP over DVB-S via ULE research page: http://nrg.cs.usm.my/satellite_ule.htmhttp://nrg.cs.usm.my/satellite_ule.htm

Bidirectional module research page: Bidirectional module research page: http://nrg.cs.usm.my/ule.htmhttp://nrg.cs.usm.my/ule.htm

Coordinator: Coordinator: [email protected]@cs.usm.my Developers: Developers: [email protected]@nrg.cs.usm.my, ,

[email protected]@nrg.cs.usm.my, , [email protected]@nrg.cs.usm.my..

implementation of ip mesh network using ule protocol over dvb-s links wan tat chee network research...

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