[AGENT++] SNMP views. v2 and v3

[Isaac Nickaein]

Hi Pedro,

Frank has already explained VACM role and its relation to the MIB.

I just wanted to add that if you are looking to implement an SNMP
agent that support SNMP v1/v2 and SNMPv3 *simultaneously*, it also can
be easily done with Agent++:

You just need to implement an SNMPv3 agent and _emulate_ SNMPv2
authentication (e.g. public and private community) by adding
appropriate entries to the VACM and other SNMPv3 tables.

Bests,
Isaac