SNMPv2 has been released as a recommended Internet standard.
Simplicity is the main reason for the success of SNMP. On a large and complicated network with devices from multiple vendors, a management protocol is required to provide specific functions to simplify management. However, to make the protocol simple, SNMP:
Does not provide the batch access mechanism and has low access efficiency of bulk data.
Only is able to run on TCP/IP networks.
Does not provide a communication mechanism for managers and is therefore suitable for only centralized management, not distributed management.
Is suitable for monitoring network devices, not a network.
In 1996, the Internet Engineering Task Force (IETF) issued a series of SNMP-associated standards. These documents defined SNMPv2c and abandoned the security standard in SNMPv2.
SNMPv2c enhances the following aspects of SNMPv1:
Structure of management information (SMI)
Communication between workstations
Protocol control
SNMPv2c abandons SNMPv2 security improvements and inherits the message mechanism and community concepts in SNMPv1.
Get-Bulk PDUs: A Get-Bulk PDU is generated on the workstation. The Get-Bulk operation (transmission of Get-Bulk PDUs) is implemented based on Get-Next operations. The Get-Bulk operation enables the workstation to query managed object group information. One Get-Bulk operation equals several consecutive Get-Next operations. You can set the recycle times for a Get-Bulk PDU on the workstation. The recycle times equal the times for performing Get-Next operations during a one-time packet exchange on the host.
Inform-Request PDUs: An Inform-Request PDU is generated on the agent. The Inform-Request operation (transmission of Inform-Request PDUs) provides a guarantee for the trap mechanism. After the agent sends an Inform-Request PDU, the workstation should return an acknowledge message to notify the agent of successful receipt of the Inform-Request PDU. If the acknowledge message is not returned within a specified period, the Inform-Request PDU is retransmitted until the number of retransmission times exceeds the threshold.