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Mitigating Network Impact

Overview​

The Mapped Universal Gateway (UG-AGENT) was designed from the ground up to be a good network citizen. It achieves this by:

  • Maintaining a local state tracking database of discovered devices, points and their property values. This allows UG-AGENT to:
    • Only send deltas (changes) to the cloud, minimizing network load
    • Recover quickly from upgrades and failure conditions like a network / power outage without requiring a full scan
  • Passively observing broadcasts on the network, minimizing the need for active interrogation. For example, when a new BACnet device comes online, it will send an I-Am packet on the network. UG-AGENT sees this message on the network and stores it in its tracking database.
  • Subscribing to Change of Value Notifications (COV) or protocol equivalents when available. This allows field controllers to control the pace of network traffic (pub/sub instead of polling).
  • Configurable polling intervals. By default, UG-AGENT polls for new data once every 15 minutes. This is easily configurable - for customers with extremely sensitive networks, the polling interval can be set even slower, though trends with intervals slower than 15 minutes may be less valuable.
  • Efficient Reads. Even for a large building with 100k+ points, the load on the network is quite minimal. Only a subset of the properties are read per device and UG-AGENT uses ReadProperty-Multiple or protocol equivalent when supported by the device / controller.

Avoiding Excessive Load​

  • The Mapped gateway is configured in read-only mode by default. In this mode, UG-AGENT will never write any properties to the network. In most cases, IP controllers rarely have any load related concerns. Issues are more common using serial communication, where throughput can be impacted by the distance between devices as well as bottlenecks created by the addition of controls from system expansion.
  • The Mapped gateway is either a small hardware gateway, or software running in a container or virtual machine. If it is ever suspected that Mapped is the source of an issue, the gateway can be unplugged or the software safely shut down, allowing time for further investigation.
  • The gateway is also configured to run all the different types of scans at very limited frequencies and concurrency. We start off at very small increments to reduce potential impact, which can be increased as needed.
  • We also only scan a handful of protocols by default. BACnet, Modbus, CBus, KNX and OPC-UA are the only enabled protocols when the gateway goes live. Additional options can be enabled if present on the network and required.

BACnet MS/TP Network Safeguards​

Mapped applies several safeguards when communicating with BACnet MS/TP devices to minimize network traffic and protect older, bandwidth-constrained serial networks.

  • Request Concurrency Limits: By default, the gateway allows up to three concurrent requests through each MS/TP router. This limit is configurable and operates independently of the gateway's broader scanning concurrency settings. Requests proceed independently, with new requests starting as capacity becomes available rather than being sent in large batches.
  • Request Management and Error Handling: The gateway accounts for device response times and applies backoff when requests time out or encounter non-retryable errors. Slow responses naturally limit additional traffic because they occupy an available request slot until completion or timeout. The gateway also respects each device's configured Application Protocol Data Unit (APDU) timeout, retry count, and segmentation timeout settings.
  • Optimized BACnet Reads: The gateway evaluates each device's advertised protocol capabilities to select an efficient supported read method. When a device supports ReadPropertyMultiple, the gateway retrieves multiple properties in fewer requests, reducing communication overhead on the serial network.
  • Compatibility with Older Devices: The gateway respects each device's advertised maximum APDU size when determining how to divide requests. If a device cannot successfully process ReadPropertyMultiple, the gateway falls back to individual ReadProperty requests and records that limitation to avoid repeatedly attempting an unsupported operation.

Together, these safeguards balance data acquisition with the performance limitations of older serial infrastructure. Mapped can also adjust the concurrent request limit to accommodate particularly sensitive or heavily utilized networks.

Lab Testing​

  • In order to test every update to UG-AGENT, Mapped maintains a lab with over 300 endpoints: devices, controllers, and BMS systems. We perform end to end testing in this lab before every software release, in order to ensure any possible network impact is identified and resolved prior to installation in a customer network.