netsukuku/doc/main_doc/ntk_rfc/Ntk_life_probability

== NTK_RFC 0005 ==

Subject: Life probability 

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This text describes a change to the Npv7.
It will be included in the final documentation, so feel free to correct it.
But if you want to change the system here described, please contact us first.
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Statistically the probability of a node to continue to stay up is related to
its uptime, for example if the node X has an uptime of 30 seconds and the node Y of
1200 seconds, then it is more probable that the node Y will continue to stay
up.

For this reason we give higher credits to older nodes/gnodes, this means that
in a multipath route we prefer to don't use very young nodes as main gateways.

{{{
		A
	       / \
	      L   K
	       \ /
                N
}}}

Let's say K has an uptime of 600 seconds and L of 200.
The node N, to reach A, will prefer the node K.

=== Implementation ===

In order to implement this we penalize the new nodes/gnodes by increasing
their rtt, in this way they will be considered as slow links.

We can do this only for new nodes/gnodes 'cause we cannot trust the uptime
value given by a node, but we can know for sure if that node is completely
new.

When the next qspn_round updates the routes the penality is removed.

Another system would be counting the number of qspn_rounds the nodes took part
in.
If it has only partecipated in < 3 rounds it is considered young.

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related: [Netsukuku_RFC]