Simple Network Management Protocol (SNMP) is an Internet-standard protocol for managing devices on IP networks.
SNMP is defined by a series of IETF Requests for Comment (RFCs). There are three versions of the protocol: SNMPv1, SNMPv2, and SNMPv3. RFC 3584 is the "Best Current Practice" for handling coexistence of the three protocol versions, and provides a view of interoperability issues between the versions as well as a list of references to the various RFCs that define the different versions.
SNMP generally operates over UDP on IPv4, but several transport mappings are defined in RFC 3417.