Relay Architecture

Types of Relays

The Althea network runs and grows via relays. Relays are separated into two categories:

1. Primary Relays – the backbone of the network using higher-end, typically deployed on businesses, tall buildings, other areas where either the size and appearance, or the strategic location of the relay, facilitates / necessitates the placement of radios capable of high throughput (for connecting larger numbers of customers) or long distance hops (connecting geographically disparate locations).
2. Sub Relays – Relays installed on customer premises. These are typically lower-end, inexpensive radios that connect neighbor-to-neighbor over short distance hops.

Both primary and sub relays can utilize a single, or combination of two types of radios:

1. Point-to-point radios (PtP) – these radios connect from only one location to another.
2. Point-to-multi-point radios (PtmP) – these are deployed where one location is suited to connect multiple customers.

For reference on the types of hardware used for relays see this Relay Hardware.

Relay Network Topology

At the most fundamental level relay topology looks like this:

flowchart TB
    Althea-Network-->Client-Radio01
    subgraph Relay [Althea Relay]
    Client-Radio01-->Althea-Router01
		Althea-Router01-->PtP-RelayLink
	  end
		PtP-RelayLink-->Client-Radio02
		Client-Radio02-->Althea-Router02

To details of this topology are as follows:

1. Client Radio – this is where the connection comes into the Althea router, either directly from the gateway, or fed by another upstream relay.
2. Althea Router – the althea router serves multiple purposes:
   1. it holds the routing table of other mesh nodes via bable network routing service so that traffic knows what the fastest route through the network is.
   2. it sets the price to be paid to the relay host (in dollars / cents) so that traffic knows the cheapest route through the network via the batman service.
3. PtP Relay Link: this radio is what provides connectivity to nodes further downstream. As noted above this radio can be either a point-to-point radio (connecting one customer to another), or a point-to-multi-point radio / sector antenna (connecting one customer to multiple customers). Each relay location can also be constructed of multiple point-to-point or point-to-multi-point radios. If the relay radio you are deploying is a sector antenna make sure you follow these best practice steps found on this Althea forum thread.

It is important to note that at each relay location all three of these components are vital for the purposes of providing the information of fastest and cheapest route through the network. The Althea router is also what contains the wallet from which the customer pays for bandwidth used, and gets paid for relayed bandwidth.

You can extrapolate out from this simple topology the application of multiple PtP or PtmP radios, where a relay would connect multiple downstream customers and additional relays. Which would look like this: