45 lines
2 KiB
Text
45 lines
2 KiB
Text
This document describes how nodes in a VPN find and connect to eachother and
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maintain a stable network.
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Copyright 2001-2006 Guus Sliepen <guus@tinc-vpn.org>
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Permission is granted to make and distribute verbatim copies of
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this documentation provided the copyright notice and this
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permission notice are preserved on all copies.
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Permission is granted to copy and distribute modified versions of
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this documentation under the conditions for verbatim copying,
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provided that the entire resulting derived work is distributed
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under the terms of a permission notice identical to this one.
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$Id$
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1. Synchronisation
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==================
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Each tinc daemon has zero or more connections to other tinc daemons. It will
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try to keep its own information synchronised with the other tinc daemons. If
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one of its peers sends information, the tinc daemon will check if it is new
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information. If so, it will update its own information and forward the new
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information to all the other peers.
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This scheme will make sure that after a short amount of time all tinc daemons
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share the same information. It will also almost completely prevent information
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from looping, because "new" information that is already known is ignored and
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not forwarded any further. However, since information can also be deleted
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there's the possibility of a looping sequence of add/delete messages. This is
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resolved by additionaly adding a unique identifier to each broadcasted message.
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Messages are dropped if the same message with that identifier has already been
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seen.
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2. Routing
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==========
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Every node tells its peers to which other peers it is connected. This way
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every node will eventually know every connection every node has on the VPN.
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Each node will use graph algorithms to determine if other nodes are reachable or not and
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what the best route is to other nodes.
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Because all nodes share the same information, using a deterministic algorithm
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each node will calculate the same minimum spanning tree for the entire VPN.
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The MST will be used to send broadcast VPN packets.
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