Internet and Satellite 1/9/2003

Transcription

1 Internet and Satellite 1/9/2003 JSAT Co./WIDE Project Jun TAKEI Day1 Agenda Satellite communication fundamentals The history of satellite communications and internet Day2 Satellite internet technology Future and expected satellite internet technology

2 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

3 Topology A: Bi-directional Link VSAT Style Topology Both way communication via satellite Topology B: Unidirectional Link Network Connection Satellite receiver work as a router. Connect a network or host.

4 Topology C-1:unidirectional Link Host Connection Route IP traffic by IP address assignment. Topology C-2: Host Connection Route IP traffic by proxy server.

5 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

6 UDLR - RFC3077 IETF UDLR-WG. Established First RFC, RFC3077 released in 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. BDL Router BDL UDL UDL Router

7 RFC3077 (Cont.) Routing program expect a response of a routing message should be returned from the same network interface. UDL UDL Router 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.

8 Definition. LLTM Feed: A router which has a send only interface. Receiver: A router which has a receive only interface. DECAP ENCAP TCP Feed IP Receiver LL UDL BDL 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.

9 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 server 2. IP address assignment: IP routing

10 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.

11 Host Connection Model 2 Assign IP address on UDL if and forward the traffic via satellite. Host Connection Model 2: SLCP Satellite link configuration protocol UDL 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

12 TCPSAT IETF TCP over satellite (TCPSAT)-WG Feb. RFCs. RFC2488 enhancing TCP over satellite channel using standard mechanism, Jan RFC2760 ongoing TCP research related to satellite, Feb 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.

13 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.

14 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.

15 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.

16 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)

17 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-RCS IPv6 on UDLR Network modeling with OBP satellite Contents distribution via satellite IP network. New cording mechanism. Security Etc.

18 Enjoy real satellite Internet on AI 3!