netsukuku/doc/main_doc/ntk_rfc/Ntk_restricted_ip_classes

== NTK_RFC 0008 ==

Subject: Private IP classes in restricted mode

----
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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The user can decide to use, in restricted mode, a different private IP
class from the default one ( 10.x.x.x ). This is useful if the 10.x.x.x class
cannot be used, for example in Russia, it is very popular to provide Internet
access through big LANs which use the 10.x.x.x class.

The other available classes are:
{{{
172.16.0.0  - 172.31.255.255    = 16*2^16 = 1048576 IPs
192.168.0.0 - 192.168.255.255   =    2^16 = 65536   IPs
}}}

The 192.168.x.x class cannot be used as an alternate restricted mode IP class
because it is the default Netsukuku private class, thus the only alternative
to 10.x.x.x is the "172.16.0.0 - 172.31.255.255" IP class.
However it is adviced to always use the default class.

== Netsukuku private classes ==

It necessary to provide at least one private IP class inside Netsukuku to
allow the creation of private LANs which are connected to Netsukuku with just
one node.

The default Netsukuku private class is 192.168.x.x.
The random IPs choosen by the nodes will be never one of that class.
The default private class is valid both in normal and restricted mode.

Only in normal mode the "172.16.0.0 - 172.31.255.255" class becomes private.
This class is assigned to very large private networks.

The 10.x.x.x class IS NOT private since it is too big and it would be just a
waste of IP addresses to use it as a private class.
Note also that for each Netsukuku node you can have a private network,
therefore with just 16 Netsukuku nodes you can form a private network of
16777216 nodes, which is equivalent to a 10.x.x.x class.

== Notes on the restricted mode ==

A node which runs in restricted mode cannot be compatible with normal mode
nodes, for this reason a restricted node will drop any packets coming from a
normal node.

While in restricted mode the "172.16.0.0 - 172.31.255.255" class IS NOT
private.

In restricted mode, when two different networks which use different
private classes (say 10.x.x.x and 192.168.x.x) are linked, nothing happens and
they will not rehook, this is necessary because it's assumed that the specified
private class is the only choice the user can utilize.
This leds to some problems, consider this scenario:
{{{
		10.0.0.0 <-> 172.16.0.0
}}}
In this case the rehook isn't launched, so it is possible that there will be a
lot of collision.