47 lines
1.5 KiB
Text
47 lines
1.5 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 Guus Sliepen <guus@sliepen.warande.net>
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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: CONNECTIVITY,v 1.1.2.1 2001/07/22 14:04:38 guus Exp $
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1. Problem
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==========
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We have a set of nodes (A, B, C, ...) that are part of the same VPN. They need
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to connect to eachother and form a single graph that satisfies the tree
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property.
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There is the possibility that loops are formed, the offending connections must
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be eliminated.
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Suppose we start with two smaller graphs that want to form a single larger
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graph. Both graphs consist of three nodes:
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A-----B-----C
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D-----E-----F
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It is very well possible that A wants to connect to D, and F wants to connect
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to C, both at the same time. The following loop will occur:
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A-----B-----C
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| ^
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v |
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D-----E-----F
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The situation described here is totally symmetric, there is no preference to
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one connection over the other. The problem of resolving the loop, maintaining
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consistency and stability is therefore not a trivial one.
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