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DTN Interworking for Future Internet. 2007.02.19 AsiaFI School Presented by Dukhyun Chang. Contents. 1. Introduction. 2. DTN Architecture. 3. DTN in Future Internet. 4. Conclusion. Introduction. Current Internet. Assumptions on TCP/IP based Internet
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DTN Interworking for Future Internet 2007.02.19 AsiaFI School Presented by Dukhyun Chang
Contents 1 Introduction 2 DTN Architecture 3 DTN in Future Internet 4 Conclusion
Current Internet • Assumptions on TCP/IP based Internet • end-to-end path exists bet’n peers • round-trip time bet’n any nodes is not excessive • end-to-end packet drop prob. is small • ..
What is Challenged Networks? • Challenged Networks • violate one or more of the assumptions
Vehicular Network Sensor network Sensor Network Sensor network What is Challenged Networks? • Terrestrial Mobile Networks • Exotic Media Networks • Military Ad-hoc Networks • Sensor Networks..
Characteristics of Challenged Networks • Path and Link Characteristics • High Latency & Low Data Rate • long propagation delay • asymmetric data rates • =>how to reduce round-trip exchanges • =>how to ensure reliability • Disconnection • motion & low duty-cycle • =>how to pre-schedule • Long Queuing Time • hours or days • =>how to select next hop
Characteristics of Challenged Networks • Network Architectures • Interoperability Considerations • =>how to make minimal assumptions of the underlying protocol • Security • =>how to exchange keys • End System Characteristics • Limited Longevity • =>who verify delivery • Limited Resources • =>how to reduce buffer usage
Some Solutions for Challenged Networks • The Internet’s Common Protocols • TCP, SCTP, UDP, IP, BGP, SMTP • degraded performance • timeouts • lack of failover • synchronous programming • chatty application protocol • E-Mail • TCP-based • chatty • provide significant number of useful features
What is DTN? • Delay and Disruption Tolerant Networks • RFC 4838, April 2007 • Delay? • Interplanetary networks • RTT from Earth to Mars • Eight minutes ~ 40 minutes • Disruption? • Sensor networks • Nodes sleep to save power • Vehicular networks • Mobile devices leaving each others’ radio ranges • Opportunistic networks • a sender and receiver make contact at an unscheduled time
DTN Architecture • DTN Architecture • Bundles • Store and Forward • DTN Endpoint • set of DTN Nodes • engines for sending and receiving bundles • an implementation of the bundle layer
DTN Architecture Descriptions • Naming/Addressing • Endpoint Identifiers (EID) • URI (RFC3986) • scheme-specific part (SSP) • registration • desire to receive ADUs destined for a particular EID • Late Binding • late binding of a bundle’s destination to a particular set of destination IDs or addresses • Pros • Route efficiently in the case of invalid connections • favors in small transit time of a message • reduce the amount of admin info propagated thru the network
C S D DATA DTN Architecture Descriptions • Routing and Forwarding • No specific routing schemes • Options for Reliability • end-to-end acknowledgment • Custody Transfer • hop-by-hop reliability • allow the source to delegate retransmission responsibility
DTN Architecture Descriptions • Fragmentation and Reassembly • Proactive Fragmentation • a DTN node may divide a block of application data into multiple smaller blocks • Reactive Fragmentation • when a bundle is only partially transferred, fragment a bundle cooperatively
Research Issues • Anycast and Multicast • how to design the case which new node joining after messages generated • Congestion and Flow Control at the Bundle Layer • Security • [DTNSEC], [DTNSOV] • Etc.
DTN in Future Internet • Current DTN can be a part of future internet • Some Considerations • Future DTN Scenarios • Emergency Network • multicast/anycast • … • Future Internet Component Technologies • Cognitive Radio • Software Defined Radio • Active Networks • …
DTN Research Issues in Future Internet • Transport Layer Protocol and Congestion Control in DTN • Integrating between heterogeneous transport protocols • Congestion control • Buffer management • Delay Tolerant Network Architecture • DTN + Future Internet Technology • assumes CR, GPS, storage, mobility, etc • Overall redesign or Extending Bundle Protocol • Routing Protocols • additional conditions and leverages • Storage, connectivity, positions, mobility • Distributed Caching • Reducing delay and traffic • Multicast/Anycast • Multicast group management • Authentication mechanism
Conclusion • The Delay and Disruption Tolerant Network will not be a future internet itself. • But it can be a important part of Future Internet. • There are many research issues in DTN, specially related future internet • New DTN Architecture • Multicast/Anycast • Routing • Security • …
References • A Delay-Tolerant Network Architecture for Challenged Internets, ACM Sigcomm 2003 • Forrest Warthman, Delay-Tolerant Networks (DTNs): A Tutorial v1.1, Mar 2003 • http://www.ietf.org/rfc/rfc4838.txt