Transcript DTN Interworking for Future Internet

DTN Interworking for
Future Internet
2007.02.19 AsiaFI School
Presented by Dukhyun Chang
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Contents
1
Introduction
2
DTN Architecture
3
DTN in Future Internet
4
Conclusion
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Introduction
3
Current Internet
Assumptions on TCP/IP based
Internet
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
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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
..
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What is Challenged Networks?
Challenged Networks

violate one or more of the assumptions
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What is Challenged Networks?



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Terrestrial Mobile Networks
Exotic Media Networks
Military Ad-hoc Networks
Sensor Networks..
Vehicular
Network
Sensor
network
Sensor
SensorNetwork
network
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Characteristics of Challenged Networks
Path and Link Characteristics

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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
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Characteristics of Challenged Networks
Network Architectures

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Interoperability Considerations
 =>how to make minimal assumptions of
the underlying protocol
Security
 =>how to exchange keys
End System Characteristics
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Limited Longevity
 =>who verify delivery
Limited Resources
 =>how to reduce buffer usage
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Some Solutions for Challenged Networks
The Internet’s Common Protocols
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TCP, SCTP, UDP, IP, BGP, SMTP
degraded performance
 timeouts
 lack of failover
 synchronous programming
 chatty application protocol
E-Mail

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TCP-based
chatty
provide significant number of useful features
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DTN Architecture of
DTNRG
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What is DTN?
 Delay and Disruption Tolerant Networks

RFC 4838, April 2007
 Delay?

Interplanetary networks
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RTT from Earth to Mars
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Eight minutes ~ 40 minutes
 Disruption?

Sensor networks
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Vehicular networks
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Nodes sleep to save power
Mobile devices leaving each others’ radio ranges
Opportunistic networks
 a sender and receiver make contact at an
unscheduled time
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DTN Architecture
DTN Architecture
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Bundles
 Store and Forward
DTN Endpoint
 set of DTN Nodes
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engines for sending and receiving bundles
an implementation of the bundle layer
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DTN Architecture Descriptions
 Naming/Addressing
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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


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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
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DTN Architecture Descriptions
Routing and Forwarding


No specific routing schemes
Options for Reliability
 end-to-end acknowledgment
 Custody Transfer


S
hop-by-hop reliability
allow the source to delegate retransmission
responsibility
D
C
DATA
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DTN Architecture Descriptions
Fragmentation and Reassembly
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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
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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.
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DTN in Future Internet
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DTN in Future Internet
 Current DTN can be a part of future
internet
 Some Considerations

Future DTN Scenarios
 Emergency Network
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
multicast/anycast
…
Future Internet Component Technologies
 Cognitive Radio
 Software Defined Radio
 Active Networks
 …
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Emergency Network Scenario Example
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DTN Research Issues in Future Internet
 Transport Layer Protocol and Congestion Control in
DTN
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Integrating between heterogeneous transport protocols
Congestion control
Buffer management
 Delay Tolerant Network Architecture
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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
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Multicast group management
Authentication mechanism
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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
…
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References
1. A Delay-Tolerant Network
Architecture for Challenged
Internets, ACM Sigcomm 2003
2. Forrest Warthman, Delay-Tolerant
Networks (DTNs): A Tutorial v1.1,
Mar 2003
3. http://www.ietf.org/rfc/rfc4838.t
xt
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