The datamodel implementation has been written in 'C' programming language and is being installed as a bbfdm micro-service to expose the datamodel functionality. The backend of various diagnostics are implemented using 'shell' programming.

Currently DownloadDiagnostics has two variant, for an7581 based chipsets, its usages Airoha fastpath tr143 implementation using speed_test module, for rest of the platforms it mostly relies on Curl utility.

Limitations with fastpath/speed_test module for DownloadDiagnostic

Only available for an7581 chip targets
'speed_test' module does not support 'https' protocol
This module do not provide protocol based error codes when fails, so to show the actual failure in the output, current implementation uses libcurl to collect the exact error code.
This module fails to download with IPv6 address so backend uses legacy mechanism (i.e. curl) to perform the diagnostic with IPv6 addresses.
DownloadDiagnostic with 'FTP' protocol is not yet implemented with 'speed_test' and hence depends on the curl based mechanism.
'speed_test' module provides the timestamps for all time related parameters like ROMTime, BOMTime, EOMTime etc as below: ROMTime:(1751006637:323389120) BOMTime:(1751006637:388715440) EOMTime:(1751006638:500266320)

As per our understanding the second part after the ':' should be in usec unit, but usec couldn't be in 9 digits form. So currently backend treats it as nsec and converts it to usec to produce the output.

Summary

Airoha fastpath (speed_test module) currently used in 'DownloadDiagnostics' on an7581 platform and it only works with 'http' protocol on 'IPv4' network.