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A Delay-Tolerant NetworkArchitecture for Challenged

Internets

Mayur MuleyTE IT 11238

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Outline

Introduction

Challenged Internet

Characteristics of Challenged internets & Current solutions

Can we use TCP/IP for architecture?

A Delay Tolerant Message Based Overlay Architecture

Application Interface

Conclusion

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Introduction

Three key assumption to achieve today’s end-to-end inter-process communication:

1.An end-to-end path exists between a data source and itspeer(s).

2.The maximum round-trip time between any node pairs in

the network is not excessive.

3.The end-to-end packet drop probability is small.

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Challenged Networks

What is challenged network?

Communication environment where expectation of link or path

characteristics no longer hold

Challenged networks :

1.Exotic Media Networks.

2.Military Ad-Hoc Networks..

3.Sensor/Actuator Networks.

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Challenged networks ( cont. )

A general purpose message-oriented reliable overlayarchitecture as the appropriate approach to tie togethersuch networks, forming an “ internetwork of challenged

internets.”  Its design is influenced by :

the internet design( interoperability)

The non-interactive delivery semantics of electronic mail

US Postal System.

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Current solutions

Some approaches to adapt Internet to unusual

environments:

1.Link-repair approaches.

2.Use proxy agents.

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Characteristics of Challenged Networks

Path and Link Characteristic

1.High Latency, Low Data Rate.

2.Disconnection: Non-faulty disconnections

A. Motion

B. Low-duty-cycle

3.Long Queuing Times

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Characteristics of Challenged Networks

Network Architectures

1.Interoperability Considerations.

Networks may use application-specific framing formats,data packet size restrictions, limited node addressing andnaming etc.

2.Security:

typically require some exchange of challenges or keys.

Uses base idea of public key encryption technique.

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Can we use TCP/IP?

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Ans : No

WHY ? Reasons are:

◦ Transport layer (TCP)

High latency and moderate to high loss rates severely limit TCP’sperformance

◦ Network layer (IP)

Performance affected by loss of fragments

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Can we use TCP/IP?

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A DELAY TOLERANT MESSAGEBASED OVERLAY ARCHITECTURE

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Abstraction

Message switching

◦ Use message aggregates or “bundles”  

Allows network’s path selection and scheduling functions a-

priori knowledge of the size and performance requirementsof data transfers

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Regions and DTN Gateways

DTN gateways are interconnection points betweendissimilar network protocol and addressing families called

regions◦ e.g. Internet-like, Ad-hoc, Mobile etc.

Function of DTN gateways :

◦ Perform reliable message routing

◦ Perform security checks

◦ Store messages for reliable delivery

◦ Naming & addressing

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October 14, 2013 Anshul Kantawala 14

Name Tuples

Two variable length portions

◦ Region name Globally-unique.

Used by DTN gateways for forwarding messages

◦ Entity name Resolvable within the specified region, need not beunique outside it

◦ E.g. { internet.icann.int, http://www.ietf.org/ }

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Class of Service

Similar to the Postal service

◦ Delivery priority: low, ordinary, high

◦ Notifications of mailing, delivery to receiver and routetaken

◦ Reliable delivery using custody transfer at each routinghop

Regions and DTN Gateways

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Security

Each message contains◦ Identity of sender

◦ Requested class of service (CoS)

Use public key cryptography

First DTN router verifies user and validates CoSrequest.◦ Re-signs message using its key and sends it back

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APPLICATION INTERFACE

The DTN architecture is built as an overlay

network using messages as the primary unit of data interchange.

Application interface is non-blocking

◦ Also has registration and callback functionsbetween bundle-based applications and the localforwarding agent

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Conclusion

DTN architecture attempts to provide interoperablecommunications between and among challenged networks.

Design uses message switching with in-networkretransmission, late-binding of names and routing tolerantof network partitioning.

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THANK YOU!!

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ANY QUESTIONS ?

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