Add backends documentation.

Author: brocaar

docs/config.toml

@@ -25,26 +25,33 @@ pygmentsUseClasses = true
     url = "/gateway/"
     weight = 3
 
+[[menu.main]]
+	pre = "<i class='fas fa-cogs'></i>"
+	name = "Backends"
+	identifier = "backends"
+	url = "/backends/"
+	weight = 4
+
 [[menu.main]]
 	pre = "<i class='far fa-file-alt'></i>"
 	name = "Payloads"
 	identifier = "payloads"
 	url = "/payloads/"
-	weight = "4"
+	weight = 5
 
 [[menu.main]]
     pre = "<i class='fas fa-code'></i>"
     name = "Integrate"
     identifier = "integrate"
     url = "/integrate/"
-    weight = 5
+    weight = 6
 
 [[menu.main]]
     pre = "<i class='fab fa-github'></i>"
     name = "Community & support"
     identifier = "community"
     url = "/community/"
-    weight = 6
+    weight = 7
 
 [params]
     version = "3.0.0-test.1"

docs/content/backends/basic-station.md

@@ -0,0 +1,36 @@
+---
+title: Basic Station
+description: Semtech Basic Station packet-forwarder backend.
+menu:
+  main:
+    parent: backends
+---
+
+# Semtech Basic Station packet-forwarder
+
+The [Semtech Basic Station](https://doc.sm.tc/station/) backend implements
+the [LNS protocol](https://doc.sm.tc/station/tcproto.html). It exposes a
+websocket handler to which Basic Station powered gateways can connect.
+
+It supports the following authentication modes:
+
+* No Authentication
+* TLS Server Authentication
+* TLS Server and Client Authentication
+
+## Channel-plan / `router_config`
+
+When using Basic Station powered gateways, assigning a _Gateway Profile_ to a
+gateway within LoRa (App) Server is a requirement. As part of the connection
+handshake, LoRa Gateway Bridge must send the channel-plan configuration to the
+Basic Station. The flow for this is:
+
+* Basic Station sends a `version` message to the LoRa Gateway Bridge
+* The LoRa Gateway Bridge sends a `stats` [Event]({{<ref "payloads/events.md">}})
+* [LoRa Server](/loraserver/) responds with a `config` [Command]({{<ref "payloads/commands.md">}}), containing the channel-plan from the _Gateway Profile_
+* The LoRa Gateway Bridge forwards this as `router_config` to the Basic Station
+
+## Known issues
+
+* The Basic Station does not send RX / TX stats
+

docs/content/backends/semtech-udp.md

@@ -0,0 +1,67 @@
+---
+title: Semtech UDP
+description: Semtech UDP packet-forwarder backend.
+menu:
+  main:
+    parent: backends
+---
+
+# Semtech UDP packet-forwarder backend
+
+The [Semtech UDP packet-forwarder](https://github.com/lora-net/packet_forwarder)
+backend abstracts the [UDP protocol](https://github.com/Lora-net/packet_forwarder/blob/master/PROTOCOL.TXT).
+
+It is compatible with:
+
+* v1 of the protocol
+* v2 of the protocol
+* Modified format used by the [Kerlink iBTS](https://www.kerlink.com/product/wirnet-ibts/)
+  containing the (encrypted) fine-timestamp
+
+## Configuration
+
+When the `semtech_udp` backend has been enabled, make sure your packet-forwarder
+`global_conf.json` or `local_conf.json` is configured correctly, under `gateway_conf`,
+the `server_address`, `serv_port_up` and `serv_port_down` must be configured so
+that data is forwarded to the LoRa Gateway Bridge instance.
+
+{{<highlight text>}}
+"gateway_conf": {
+	"gateway_ID": "AA555A0000000000",
+	"server_address": "localhost",
+	"serv_port_up": 1700,
+	"serv_port_down": 1700,
+	...
+}
+{{</highlight>}}
+
+## Deployment
+
+The LoRa Gateway Bridge can be deployed either on the gateway (recommended)
+and "in the cloud". In the latter case, multiple gateways can connect to the
+same LoRa Gateway Bridge instance.
+
+When the LoRa Gateway Bridge is deployed on the gateway, you will benefit from
+the MQTT authentication / authorization layer and optional TLS.
+
+## Packet-forwarder re-configuration over MQTT
+
+The Semtech UDP backend supports the re-configuration of the packet-forwarder
+over MQTT using the `config` [Commands]({{<ref "payloads/commands.md">}}).
+
+This works as follow:
+
+* The LoRa Gateway Bridge will periodically send `stats` [Events]({{<relref "payloads/events.md">}})
+  containing the current configuration version.
+* [LoRa Server](/loraserver/) processes these stats events and when a _Gateway Profile_
+  is associated with the gateway, it will compare the configuration version.
+* In case the _Gateway Profile_ version is newer, it will send a `config`
+  command to the LoRa Gateway Bridge.
+* LoRa Gateway Bridge will then read the `base_file`, update it and writes it
+  to the `output_file`.
+* It then restarts the packet-forwarder using the `restart_command` causing the
+  packet-forwarder to reload its configuration.
+
+For the above to work, you must configure the _Mandaged packet-forwarder configuration_
+section in the `lora-gateway-bridge.toml`.
+