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58 lines
2.7 KiB
Markdown
58 lines
2.7 KiB
Markdown
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Mesh Datagram Protocol (MDP)
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============================
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[Serval Project], May 2014
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The [Mesh Datagram Protocol][MDP] is a network protocol developed for the
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[Serval mesh network][], with characteristics that make it particularly
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suitable for use in Ad Hoc wireless networks, which can suffer high levels of
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packet loss due to weak signal, interference and congestion.
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MDP carries [datagram][] packets sent from an originating node to a single
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destination node or broadcast to all nodes, guaranteeing only that packet
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contents will be verbatim if delivered. MDP is similar to [UDP][] in terms of
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the service it provides to applications, but unlike UDP it uses a per-hop
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[retransmission][] protocol and adaptive link-state routing to boost packet
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delivery rates, which largely immunises it from the cumulative packet loss
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effect typical of wireless networks. This means that its end-to-end packet
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delivery rate remains usefully high despite adverse network conditions.
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**Copyright 2014 Serval Project Inc.** All rights reserved. Licensing terms
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to be announced.
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Overlay Mesh
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------------
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MDP packets are transmitted over a network link using the [Overlay Mesh][]
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packet format, which aggregates packets into *overlay frames* which are
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designed to minimise packet size. Each overlay frame uses back references to
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avoid repeating [SID][] addresses unnecessarily within the frame, and [SID
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abbreviation][] to significantly shorten [SID][] addresses that have been used
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in prior frames.
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MDP Interface
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-------------
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The [Serval DNA][] daemon provides an interface that allows client applications
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to send and receive individual MDP packets on the [Serval mesh network][]
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without having to construct and disassemble Overlay Mesh frames on their own.
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MDP API
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-------
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The MDP API is a [C language][] [API][] that an application can use to send and
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receive MDP packets over the [Serval mesh network][] using the
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[interface](#mdp-interface) provided by the [Serval DNA][] daemon.
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[Serval Project]: http://www.servalproject.org/
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[Serval mesh network]: http://developer.servalproject.org/dokuwiki/doku.php?id=content:tech:mesh_network
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[Serval DNA]: http://developer.servalproject.org/dokuwiki/doku.php?id=content:servaldna:
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[MDP]: http://developer.servalproject.org/dokuwiki/doku.php?id=content:tech:mdp
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[datagram]: http://en.wikipedia.org/wiki/Datagram
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[UDP]: http://en.wikipedia.org/wiki/User_Datagram_Protocol
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[Overlay Mesh]: ./Overlay-Mesh.md
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[SID]: http://developer.servalproject.org/dokuwiki/doku.php?id=content:tech:sid
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[SID abbreviation]: http://developer.servalproject.org/dokuwiki/doku.php?id=content:tech:sid_abbreviation
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[C language]: http://en.wikipedia.org/wiki/C_(programming_language)
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[API]:http://en.wikipedia.org/wiki/Application_programming_interface
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