While not perfect, SNMP provides many of the tools necessary to collect and analyze data to enable system tuning for optimum performance and to identify when and where future growth in the network is required.
An important requirement for SNMP was to minimize managed-element processing overhead. SNMP was therefore designed to collect and report information, but not to provide sophisticated information processing. For example, an SNMP-managed node doesn’t report information such as link throughput; rather, SNMP defines the information to be collected and relies on the NMS to retrieve and process the information to produce a derived value.
The Remote MONitoring (RMON) extensions to SNMP, including RMON 1 and RMON 2, were defined by the IETF to add “flow-based” monitoring, as opposed to “device-based” monitoring, which is what SNMP primarily delivers. The first version, RMON 1, defined ten management groups that focused on OSI Layer 1 and Layer 2 information in Ethernet and Token Ring networks, which help to monitor LANs. The second version, RMON 2, included ten more groups that added support for network protocol- and application-layer monitoring. Compared to standard SNMP agents, agents that fully support RMON management require more processing capability. Because of this requirement, full RMON management is typically carried out by one or more probes designed specifically for RMON.
Prior to SNMP, most network devices were managed as individual elements by proprietary network management software. These software point products could only manage a single vendor’s devices, and some were merely text-based command-line utilities.
The Simple Network Management Protocol defines a method for managing devices that connect to IP networks. The “simple” in SNMP refers to the requirements for a managed device, not the protocol. This white paper defines the history, frequently used terms, and implementation of SNMP.
Compared to previous monitoring and management methods, SNMP reduces the amount of overhead on the network element. Reduced processing overhead and a common platform enables growth and platform independence. This allows SNMP to be used on almost every IP network, often using a single, centralized NMS. While larger IP networks may require SNMP proxies to minimize WAN-based SNMP traffic, the reduction in the number of NMSs compared to previous methods enabled IT to focus on the other issues and to simplify the management network.