The snmp application in OTP does include a manager however it is not
very useful in real world use cases. For our purposes we started with
it but evolved to writing our own manager while making it an
incremental addition to the existing snmp application. Additions
include SNMP engine ID discovery and NIFs for SNMPv3 crypto.
We did reuse the snmp application's implementation at first but profiling showed us that 98% of the total time was spent doing the one million iterations required to generate a hash and was taking over 100ms each time. Moving to a NIF on the same hardware reduced it to less than 10ms.