As presently specified, SNMPv2 is incompatible with SNMPv1 in two key areas: message formats and protocol operations. SNMPv2 messages use different header and protocol data unit (PDU) formats than SNMPv1 messages. SNMPv2 also uses two protocol operations that are not specified in SNMPv1. Furthermore, RFC 1908 defines two possible SNMPv1/v2 coexistence strategies: proxy agents and bilingual network-management systems.
SNMP Proxy Agents
An SNMPv2 agent can act as a proxy agent on behalf of SNMPv1 managed devices, as follows:
The proxy agent maps SNMPv1 trap messages to SNMPv2 trap messages and then forwards them to the NMS.
SNMP Proxy Agents
An SNMPv2 agent can act as a proxy agent on behalf of SNMPv1 managed devices, as follows:
- An SNMPv2 NMS issues a command intended for an SNMPv1 agent.
- The NMS sends the SNMP message to the SNMPv2 proxy agent.
- The proxy agent forwards Get, GetNext, and Set messages to the SNMPv1 agent unchanged.
- GetBulk messages are converted by the proxy agent to GetNext messages and then are forwarded to the SNMPv1 agent.
The proxy agent maps SNMPv1 trap messages to SNMPv2 trap messages and then forwards them to the NMS.
Bilingual SNMPv2 network-management systems support both SNMPv1 and SNMPv2. To support this dual-management environment, a management application in the bilingual NMS must contact an agent. The NMS then 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.
