Simple Network Management Protocol (SNMP), an application layer protocol, facilitates the exchange of management information among network devices, such as nodes and routers. It comprises part of the TCP/IP suite. System administrators can remotely manage network performance, find and solve network problems, and plan for network growth by using SNMP.
Instead of defining a large set of commands, SNMP places all operations in a get-request, get-next-request, get-bulk-request, and set-request format. For example, an SNMP manager can get a value from an SNMP agent or store a value in that SNMP agent. The SNMP manager can comprise part of a network management system (NMS), and the SNMP agent can reside on a networking device such as a router.
SNMP comprises of three parts—SNMP manager, SNMP agent, and MIBs. You can compile the Cisco MIB with your network management software.
The NMS uses the Cisco MIB variables to set device variables and to poll devices on the internetwork for specific information. The results of a poll can get graphed and analyzed to help you troubleshoot internetwork problems, increase network performance, verify the configuration of devices, and monitor traffic loads.
The SNMP agent gathers data from the MIB, which is the repository for information about device parameters and network data. The SNMP agent also can send traps (notifications) of certain events, to the SNMP manager. The Cisco host //ftp.cisco.com makes available the Cisco trap file, "mib.traps," which documents the format of Cisco traps.
The SNMP manager uses information in the MIB to perform the operations as described:
Operation
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Description
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get-request
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Retrieve a value from a specific variable.
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get-next-request
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Retrieve the value following the named variable. Often used to retrieve variables from within a table. With this operation, an SNMP manager does not need to know the exact variable name. A sequential search gets performed to find the needed variable from within the MIB.
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get-response
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Reply to a get-request, get-next-request, get-bulk-request, and set-request that an NMS sent.
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get-bulk-request
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Fills the get-response with up to max-repetition number of get-next interactions, similar to get-next-request.
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set-request
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Store a value in a specific variable.
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traps
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Sent by an SNMP agent to an SNMP manager to indicate that some event occurred.
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