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Internet and Satellite1/9/2003

JSAT Co./WIDE ProjectJun TAKEI

takei@csm.jcsat.co.jp

Agenda

Day1– Satellite communication fundamentals– The history of satellite communications and

internetDay2– Satellite internet technology– Future and expected satellite internet

technology　

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Satellite Internet Technology

Network Topology

Bi-directional link– Satellite link as a both way communication link– Topology A: VSAT style topology

Unidirectional link– Satellite link as a unidirectional communication link– Topology B: network connection

• IP connectivity to a network

– Topology C: host connection• IP connectivity to a host

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Topology A: Bi-directional LinkVSAT Style Topology

Both way communication via satellite

The Internet

Topology B: Unidirectional LinkNetwork Connection

Satellite receiver work as a router.Connect a network or host.

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Topology C-1:unidirectional LinkHost Connection

Route IP traffic by IP address assignment.

Topology C-2:Host Connection

Route IP traffic by proxy server.

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Topology Summary

Topology A (bi-direction).– No routing capability restriction.– Use satellite link as a vent pipe.

Topology B (UDL network connection).– Need dynamic routing capability.

Topology C (UDL host connection).– Dynamic routing capability is not required.– Subsets of topology B.

Topology and the Technology

Topology A (bi-direction)– VSAT, DVB-RCS

Topology B (UDL network connection)– UDLR, RFC3077

Topology C (UDL host connection)– DirecPC, SLCP

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UDLR - RFC3077

IETF UDLR-WG.– Established 1997.– First RFC, RFC3077 released in 2000.– Aim.

• To provide dynamic routing capability mechanism on UDL network without any existing routing protocol modification.

RFC3077

“A link-layer tunneling mechanism for unidirectional links.”Current existing dynamic routing protocol assume bi-directional communication capability on each network interface.

Router RouterBDL BDL UDL

UDL

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RFC3077 (Cont.)

Routing program expect a response of a routing message should be returned from the same network interface.

RouterUDL

UDL

Link Layer Tunneling Mechanism

Hide unidirectional link from kernel level.Use GRE (generic routing encapsulation).Why GRE?– GRE designed for carry routing information.– Layer 2(link layer) encapsulation.

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LLTM

Definition.– Feed: A router which has a send only interface.– Receiver: A router which has a receive only

interface.

BDL

UDL

Feed ReceiverIPLL

TCPENCAPDECAP

LLTM (Cont.)

By employing LLTM, routing protocol can communicate on UDL.Every unicast routing protocol works fine.– RIP, OSPF, IS-IS, etc.

Multicast protocol.– Yes and no.– Reverse path forwarding mechanism.In any case, some tips needed.

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IETF UDLR-WG

Preparing next RFC.– Informational RFC.– To help UDLR operation.– Clarify issue of IP multicast operation.

Future work.– Ipv6.– Interoperability test.– Etc.

Host Connection Model

How to route return traffic to a node via satellite link?

1. Application layer: proxy server2. IP address assignment: IP routing

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Host Connection Model 1

Route return traffic by proxy server.

Host Connection Model 1:Application GW

Proxy gateway technology.Proxy server forward return traffic via satellite link.Needs software configuration on client node.Not all application program can be supported.Scalable issue.DirecPC.

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Host Connection Model 2Assign IP address on UDL if and forward the traffic via satellite.

Host Connection Model 2:SLCP

Satellite link configuration protocolUDL interface has own IP address and the return traffic forwarded to its IP address.Client node send IP packet which source IP address is UDL if’s.Need modification in IP stack– Similar concept of LLTM

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TCPSAT

IETF TCP over satellite (TCPSAT)-WG.1997-2000 Feb.RFCs.– RFC2488 enhancing TCP over satellite channel

using standard mechanism, Jan 1999.– RFC2760 ongoing TCP research related to

satellite, Feb 2000.

TCPSAT (Cont.)

Scope of WG.– Transport layer issues affecting TCP over

satellite links.– Existing TCP option.– Compliant implementations which have some

known improved performance over sat. Links.– Recommendation of well understood protocol

changes.– Etc.

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DVB

DVB.– Digital video broadcasting project.– Getting world standard in MPEG transmission.

DVB standard.– More detail specification on MPEG system.

DVB family.– DVB-S: satellite.– DVB-C: cable.– DVB-T: terrestrial.

DVB-RCS

New VSAT style communication platform.Low cost terminal and also hub system.Hub to terminal.– Forward link: about 30mbps.

Terminal to hub.– Return link: upto 2mbps.

Typical antenna size.– 60cm-90cm.

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DVB-RCS (Cont.)

Terminal equipment size– First generation

• 2u full thick pizza box

– Second generation• 1u think pizza box

– Third generation• Lunch box

DVB-RCS Hub System

2 rack redundant hub system.ESA is doing interoperability test.

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Future Satellite Communication

What is Next?

Key Technology

On board possessing.– Switch packets on the satellite.– Switch in the sky.– Router in the sky.

Multi-beam spot beam antenna.– Route traffic from a beam to another beam.

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On Board Processor

Experimental satellite test.– ACTS program by NASA.

• ATM cell switch.• Why ATM?

• Fixed length packet.• Easy to synclines.• Too large overhead!!

OBP on Commercial Satellite

EUTELSAT HotBird– MPEG packet multiplex capability– Uplink

• MPEG SCPC carrier

– Downlink• MPEG MCPC carrier• Small terminal can transmit the traffic• DVB-S small receive dish(50cm)

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IP Router in the Sky

NASA planning to launch Cisco router on orbit.C3651 mobile routing test bed.Space proven module.– Launched by small

satellite project.– Cots.

What Should We Do?Research Topics

IPv6 on DVB-RCSIPv6 on UDLRNetwork modeling with OBP satelliteContents distribution via satellite IP network.New cording mechanism.SecurityEtc.

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Enjoy real satellite Interneton AI3 !