The theory of Viphilama has been completed, its implementation will start
soon.
== Viphilama ==
Virtual to Physical Layer Mapper
Wiki version: http://lab.dyne.org/Ntk_viphilama
----
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.
----
=== Viphilama ===
Viphilama will permit to Netsukuku to expand itself over the Internet and then
switch automatically to the physical layer without interfering with the
stability of the Net.
==== Applications ====
Viphilama transforms Netsukuku into a hybrid overlay network which expands the
original structure of the Internet. Its main advantages are:
* the faster diffusion of Netsukuku: every user with an Internet
connection can join Netsukuku
* the creation of a scalable network which is built upon the Internet
but is completely separated from it.
* the automatic switch from the Netsukuku overlay network to the
physical one
* the freely registration of domain names (see ANDNA).
* the usage of Carciofo ( http://lab.dyne.org/Ntk_carciofo ) over the
Internet.
* the workaround of NAT restrictions: even with only one Internet
connection it is possible to connect an entire LAN to Viphilama.
Inside Viphilama, every node of the LAN will get a unique IP,
therefore the NAT restriction imposed by the ISP (if you want more
IPs you have to pay) is ignored.
* other ...?
==== Basic idea ====
The basic idea of Viphilama is to connect, with Internet tunnels, nodes which
aren't physically linked.
Then whenever, Viphilama finds that a virtual link can be replaced by a
physical one, it removes the virtual link.
Assume this scenario:
{{{
Tokyo Moscow Rome London
| | | |
| | | |
|__________|Internet tunnel|_________|
}}}
All the cities are linked with Internet tunnels.
When Tokyo and Moscow will be linked by a series of physical nodes, Viphilama
will change the net in this way:
{{{
Tokyo<--ntk nodes-->Moscow Rome London
| | |
|______ Internet tunnel ___|
}}}
When even Moscow and Rome will be linked by physical nodes:
{{{
Tokyo<--ntk nodes-->Moscow<--ntk nodes-->Rome London
| |
|__ Inet tunnel _|
}}}
And finally:
{{{
Tokyo<--ntk nodes-->Moscow<--ntk nodes-->Rome<--ntk nodes-->London
}}}
This is only the general description of the Viphilama idea, actually, the
implementation is a bit more complex ;)
=== Layer ===
Netsukuku will be split in two layer: the virtual layer and the physical one.
==== The physical layer ====
The physical layer is the original Netsukuku layer: every node is linked to
other nodes by physical links (wifi, cables, ...).
The physical layer is prioritised over the virtual one.
==== The virtual layer ====
The virtual layer is built upon the Internet or any other existing network.
The Netsukuku nodes, in this layer, are linked each other by tunnels.
===== Coordinates =====
A node, in order to join in the virtual layer, has to know its physical
coordinates.
The use of geographical coordinates is required for Viphilama, because it has
to map the virtual layer to the physical one and it needs a way to measure
the effective distance between two virtual nodes.
The coordinates can be retrieved using an online map service like
http://maps.google.com or with a GPS.
The coordinates are stored in the internal, external and bnode maps.
In the internal map there are the coordinates of each single node.
In the external maps, the coordinates which locate a gnode are set to its
barycenter: it is the average of the coordinates of all its internal nodes.
The coordinates don't affect the anonymity of the user worse than the
Internet does, in fact, it is possible to make a guess about the geo location
of an IP (see xtraceroute).
If the user doesn't specify its accurate location, then the xtraceroute method
will be used to retrieve an approximated location.
Two nodes may share the same coordinates. This happen when they use inaccurate
coordinates, i.e. xtraceroute associates the same location to two IPs of the
same city. In this case, the difference of their IPs will be used as an
(inaccurate) measure of the distance.
Or in other words:
Let d(X, Y) be the physical distance between the node X and Y.
If d(X,Y) is zero then d(X,Y) is equal to the difference of the IP of
X and Y.
===== Terminology =====
The virtual layer is composed by the same elements of the physical layer, for
this reason they have the same names but the are prefixed with 'v'.
node -> vnode
rnode -> vrnode
gnode -> vgnode
...
==== Gate node ====
The two layers are joined by the gate nodes. They are nodes which belong to
both layers.
This means that the two layer form a unique network.
The short name of a gate node is simply "gate", in this way it isn't confused
with gnode (group node).
=== Virtual to Physical mapper ===
Viphilama is the supervisor of the topology of the entire net, it shapes the
virtual layer and merges it with the physical one trying to achieve the best
balance.
It follows simple rules:
* Viphilama just optimises the topology of the network.
* The physical layer is prioritised
* The virtual layer, from the point of view of Netsukuku, has to be the same
of the physical layer, therefore it is not allowed to use specialized
network like Kademlia to shape its topology. This leads to a loss of
performance, because the virtual layer isn't optimised for the lower network
(the Internet), but it ensures consistency in the Netsukuku network.
* Each node has to be connected, with physic or virtual links, to its nearest
nodes.
* If the node A is linked physically to B, then A is one of the nearest node
to B and vice versa.
Let's go into the details.
==== Virtual hooking ====
A node, which hasn't any physical neighbours, resides in a black zone and, for
this reason, it can't hook to the physical layer. If it has access to another
network, i.e. the Internet, it will hook directly to a vnode, joining the
virtual layer.
Let this hooking node be H.
===== Searching for the nearest vrnode =====
The first part of the Virtual Hooking is the creation of virtual links
(ip tunnels) to the first vrnode it founds.
H chooses, at first, a random vnode which can be located anywhere in the
globe.
If it is its first hook to the virtual layer, it will get the IP of the vnode
from a small public list available on the Internet, otherwise it will consult
its saved virtual maps. Each IP on the public list and in the virtual maps is
associated to its own geographic coordinates. H will choose the nearest vnode
to itself.
Let the chosen vnode be V.
H sends to V a packet containing its coordinates and a random ID.
V consults its external map and forwards the received packet to the gnode G,
which is the nearest to H.
The packet will be forwarded until it gets to I, the nearest node to H, which
belongs to the gnode G.
At this point, I sends an ACK packet to H and includes in it the ID.
In this way it certifies that it has truly received the original packet, sent
by H.
I is the first vrnode of H.
===== Linking to other vrnodes =====
Since only one vrnode per vnode is not sufficient to balance the network, H
will link to other `vlinks_max' vnodes. These vnodes are the nearest to H.
`vlinks_max' is a value proportional to the bandwidth of H.
The node I appends its Internet IP to the received packet and forwards it
again to a node T, so that d(H,T) ~= d(H,I).
The node T will do the same (adds its IP and forwards the pkt).
When the packet will be forwarded for the `vlinks_max'-th time or when it can't
be
forwarded anymore, it is sent back to the node H.
The node H collects this last packet and creates a virtual link (tunnel) to
each Internet IP which has been stored in the packet itself.
These linked nodes are the new vrnodes of the node H.
===== Reordering the virtual layer =====
At this point the node H will hook to each linked node. This procedure is
called vlinking:
Let L be the generic vrnode of H.
It is possible that some vrnodes of L are nearer to H, in this case they
should be linked to H instead of L. For example:
{{{
1. Initial configuration
Tokyo London
| |
|______ Internet tunnel ___|
2. Rome vhooks to London.
Tokyo -------- London ----- Rome
3. Since Rome is nearer to Tokyo than London, the links are reordered in their
final configuration:
Tokyo -------- Rome -------- London
}}}
The reordering of the links works in this way:
H sends the I_AM_VHOOKING request to L.
L analyses its virtual rnodes and compares d(L,vR) to d(H,vR), where vR is a
vrnode. If d(H,vR) < d(L,vR), L adds the Internet IP of vR in the reply
packet.
H receives the reply packet of L and tries to create a virtual link to each
vR listed in the same packet.
H writes the list of all the vR nodes which has been successfully linked to H
itself. This list is sent back to L.
L reads this latter list and deletes all its links to the vR nodes, which has
been successfully linked to H.
This same procedure is repeated for each vrnode of H.
In the end, H chooses one of its vrnodes and hooks with the classical method
to it.
===== Gate hooking =====
When a gate node is linked physically to another gate node, they use the
v-linking procedure to reorder their links.
==== Virtual topology ====
The node H will remain virtually linked to a generic node L if and only if
there isn't a physical route which connects H to L.
When H notices (analysing the QSPN pkts) that L can be reached through a
physical route, it deletes the virtual link.
==== Load balancing ====
All the nodes, which have an Internet connection, should be gate nodes.
In this way, the traffic passing on the virtual layer will be well balanced.
For example, two separated physical gnodes will be linked with the maximum
number of virtual links.
{{{
virtual links
___ ... ____
/___ ... ____\
/____ ... _____\
/ \
Gnode A ------ ... ------- Gnode B
\_____ ... ______/
\____ ... _____/
\___ ... ____/
virtual links
}}}
==== Vlinks threshold ====
`vlinks_max' is the maximum number of vrnodes which H can have and it is a value
proportional to the bandwidth of H itself.
`vlinks_min' is the minimum number of vrnodes and is always proportional to
the bandwidth.
When the number of vrnodes becomes greater than `vlinks_max', H drops its
farest vrnodes, keeping all the others.
Instead, if the number becomes smaller than `vlinks_min', H vhooks again in
the virtual layer using the same procedure described before.
==== The end of Viphilama ====
When all the nodes will be linked with physical links, Viphilama will
automatically cease to operate. In fact, there will be always a physical route
which connects any other node and therefore all the virtual links will be
deleted.
----
Feel free to help the development of Viphilama.
--
:wq!
"I don't know nothing" The One Who reached the Thinking Matter '.'
[ Alpt --- Freaknet Medialab ]
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