Scalability
Different deployment scenarios have impact on the scalability of your LNS (LoRaWAN Network Server).
Connection ownership
The LNS is running as a module on IoT edge and processes messages from potentially multiple LBS (LoRa Basics Stations).
Due to the broadcasting of messages, the same message from the same device can reach multiple LNS.
One of the limiting factor is the connection awareness of IoT edge for its connected device clients. Edge keeps an active connection for all devices connected to it. If we have multiple open connections on multiple LNS servers for the same device identity, we experience an aggressive connection open/close pattern seriously affecting scalability of the LNS.
Starting with version 2.1 we introduce a concept for connection ownership ensuring we only keep one active connection / LNS most of the time.
To facilitate this, we track the last LNS that won the race to process a particular message. This LNS is then given an edge for future message processing for that device by a configurable amount. This allows the owning gateway to keep the connection open and keep processing messages without having to fight for the connection from other LNSes. LNSes that do not own the connection, never open it (unless for occasional cache refreshes).
This allows us to have a high percentage of single connection management towards IoT hub.
Should an owning LNS go down and a message for that device is sent, another LNS will eventually win the race and take the ownership. This guarantees seemless failover and message processing.
Ownership is tracked both locally on the LNS to determine the connection state as well as on the function. The function side is used to send a notification, in case of an ownership change, to the previously owning LNS. This is covering the case of roaming devices, where a device could move outside of the reach of the owning gateway. That means it won't get any new messages and won't notice the ownership change, unless it is being informed by the function.
Deduplication
There is a feature built into the LNS to
deduplicate messages, to
deal with duplicate messages on multiple LNS. This does
have an effect on scalability. Higher scalability as described above
can only be achieved with Drop. Any other settings
will require the connection to be opened during message processing
on multiple gateways and does not allow the ownership of a
connection on a single LNS.
Created: 2022-03-02