Editing Simple Network Management Protocol (section)

=== SNMPv1 and SNMPv2c interoperability ===
SNMPv2c is incompatible with SNMPv1 in two key areas: message formats and protocol operations. SNMPv2c messages use different header and protocol data unit (PDU) formats than SNMPv1 messages. SNMPv2c also uses two protocol operations that are not specified in SNMPv1. To overcome incompatibility, {{IETF RFC|3584}} defines two SNMPv1/v2c coexistence strategies: proxy agents and bilingual network-management systems.

==== Proxy agents ====
An SNMPv2 agent can act as a proxy agent on behalf of SNMPv1-managed devices. When an SNMPv2 NMS issues a command intended for an SNMPv1 agent it sends it to the SNMPv2 proxy agent instead. The proxy agent forwards <code>Get</code>, <code>GetNext</code>, and <code>Set</code> messages to the SNMPv1 agent unchanged. GetBulk messages are converted by the proxy agent to <code>GetNext</code> messages and then are forwarded to the SNMPv1 agent. Additionally, the proxy agent receives and maps SNMPv1 trap messages to SNMPv2 trap messages and then forwards them to the NMS.

==== Bilingual network-management system ====
Bilingual SNMPv2 network-management systems support both SNMPv1 and SNMPv2. To support this dual-management environment, a management application examines information stored in a local database to determine whether the agent supports SNMPv1 or SNMPv2. Based on the information in the database, the NMS communicates with the agent using the appropriate version of SNMP.