150 lines
7.5 KiB
ReStructuredText
150 lines
7.5 KiB
ReStructuredText
.. _networks-main:
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*****************
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Building Networks
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*****************
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This chapter will provide you with the knowledge needed to build networks with
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Reticulum, which can often be easier than using traditional stacks, since you
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don't have to worry about coordinating addresses, subnets and routing for an
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entire network that you might not know how will evolve in the future. With
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Reticulum, you can simply add more segments to your network when it becomes
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necesarry, and Reticulum will handle the convergence of the entire network
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automatically.
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Concepts & Overview
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--------------------
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There are important points that need to be kept in mind when building networks
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with Reticulum:
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* | In a Reticulum network, any node can autonomously generate as many adresses
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(called *destinations* in Reticulum terminology) as it needs, which become
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globally reachable to the rest of the network. There is no central point of
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control over the adress space.
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* | Reticulum was designed to handle both very small, and very large networks.
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While the adress space can support billions of endpoints, Reticulum is
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also very useful when just a few devices needs to communicate.
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* | Reticulum provides sender/initiator anonymity by default. There is no way
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to filter traffic or discriminate it based on the source of the traffic.
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* | All traffic is encrypted using ephemeral keys generated by an Elliptic Curve
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Diffie-Hellman key exchange on Curve25519. There is no way to inspect traffic
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contents, and no way to prioritise or throttle certain kinds of traffic.
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All transport and routing layers are thus completely agnostic to traffic type,
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and will pass all traffic equally.
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* | Reticulum can function both with and without infrastructure. When *transport
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nodes* are available, they can route traffic over multiple hops for other
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nodes, and will function as a distributed cryptographic keystore. When there
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is no transport nodes available, all nodes that are within communication range
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can still communicate.
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* | Every node can become a transport node, simply by enabling it in it's
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configuration, but there is no need for every node on the network to be a
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transport node. Letting every node be a transport node will in most cases
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degrade the performance and reliability of the network.
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In general terms, if a node is stationary, well-connected and kept running
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most of the time, it is a good candidate to be a transport node. For optimal
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performance, a network should contain the amount of transport nodes that
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provides connectivity to the intended area / topography, and not many more
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than that.
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Reticulum allows you to mix very different kinds of networking mediums into a
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unified mesh, or to keep everything within one medium. You could build a "virtual
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network" running entirely over the Internet, where all nodes communicate over TCP
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and UDP "channels". You could also build such a network using MQTT or ZeroMQ as
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the underlying carrier for Reticulum.
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However, most real-world networks will probably involve either some form of
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wireless or direct hardline communications. To allow Reticulum to communicate
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over any type of medium, you must specify it in the configuration file, by default
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located at ``~/.reticulum/config``.
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Any number of interfaces can be configured, and Reticulum will automatically
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decide which are suitable to use in any given situation, depending on where
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traffic needs to flow.
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Example Scenarios
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-----------------
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This section illustrates a few example scenarios, and how they would, in general
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terms, be planned, implemented and configured.
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Interconnected LoRa Sites
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=========================
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An organisation wants to provide communication and information services to it's
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members, which are located mainly in three separate areas. Three suitable hill-top
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locations are found, where the organisation can install equipment: Site A, B and C.
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Since the amount of data that needs to be exchanged between users is mainly text-
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based, the bandwidth requirements are low, and LoRa radios are chosen to connect
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users to the network.
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Due to the hill-top locations found, there is radio line-of-sight between site A
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and B, and also between site B and C. Because of this, the organisation does not
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need to use the Internet to interconnect the sites, but purchases four Point-to-Point
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WiFi based radios for interconnecting the sites.
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At each site, a Raspberry Pi is installed to function as a gateway. A LoRa radio
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is connected to the Pi with a USB cable, and the WiFi radio is connected to the
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ethernet port of the Pi. At site B, two WiFi radios are needed to be able to reach
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both site A and site C, so an extra ethernet adapter is connected to the Pi in
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this location.
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Once the hardware has been installed, Reticulum is installed on all the Pis, and at
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site A and C, one interface is added for the LoRa radio, as well as one for the WiFi
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radio. At site B, an interface for the LoRa radio, and one interface for each WiFi
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radio is added to the Reticulum configuration file. The transport node option is
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enabled in the configuration of all three gateways.
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The network is now operational, and ready to serve users across all three areas.
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The organisation prepares a LoRa radio that is supplied to the end users, along
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with a Reticulum configuration file, that contains the right parameters for
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communicating with the LoRa radios installed at the gateway sites.
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Once users connect to the network, anyone will be able to communicate with anyone
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else across all three sites.
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Bridging Over the Internet
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==========================
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As the organisation grows, several new communities form in places too far away
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from the core network to be reachable over WiFi links. New gateways similar to those
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previously installed are set up for the new communities at the new sites D and E, but
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they are islanded from the core network, and only serve the local users.
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After investigating the options, it is found that it is possible to install an
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Internet connection at site A, and an interface on the Internet connection is
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configured for Reticulum on the Raspberry Pi at site A.
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A member of the organisation at site D, named Dori, is willing to help by sharing
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the Internet connection she already has in her home, and is able to leave a Raspberry
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Pi running. A new Reticulum interface is configured on her Pi, connecting to the newly
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enabled Internet interface on the gateway at site A. Dori is now connected to both
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all the nodes at her own local site (through the hill-top LoRa gateway), and all the
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combined users of sites A, B and C. She then enables transport on her node, and
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traffic from site D can now reach everyone at site A, B and C, and vice versa.
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Growth and Convergence
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======================
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As the organisation grows, more gateways are added to keep up with the growing user
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base. Some local gateways even add VHF radios and packet modems to reach outlying users
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and communities that are out of reach for the LoRa radios and WiFi backhauls.
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As more sites, gateways and users are connected, the amount of coordination required
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is kept to a minimum. If one community wants to add connectivity to the next one
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over, it can simply be done without having to involve everyone or coordinate address
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space or routing tables.
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With the added geographical coverage, the operators at site A one day find that
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the original internet bridged interfaces are no longer utilised. The network has
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converged to be completely self-connected, and the sites that were once poorly
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connected outliers are now an integral part of the network.
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