SNMP is an abbreviation from Simple Network Management Protocol. This is a very useful protocol for manage and monitor network devices on the TCP/IP networks. SNMP belongs to the application layer.
SNMP protocol is composed of four main segments: SNMP manager, SNMP agent, MIB (Management Information Base) and managed device.
The NMS (Network Management System) is the SNMP manager – the NMS software on the NMS server. It is the main component of this protocol. The NMS uses SNMP messages to manage and monitor network devices in the domain of work. SNMP manager sends requests to SNMP agents to query or modify parameters, and it receives SNMP traps from SNMP agents.
Every managed network device has an SNMP agent, a MIB and multiple managed objects.
The SNMP agent is a process on the network device. SNMP manager sends request messages to the SNMP agent. Then, SNMP agent has to perform an action, and return the response message to the SNMP manager. The SNMP agent reads and writes to the MIB.
The SNMP agent does not send a request message to the SNMP manager. It only sends trap messages in case a problem occurs. These are alarm messages. The SNMP agent only sends trap messages if it is configured to send.
A MIB is Management Information Base, it is located on the managed network device. This segment of the SNMP defines the attributes – name, status, data type, etc. It is used a tree structure to store data.
There are three versions of this protocol: SNMPv1, SNMPv2c, and SNMPv3. In this article, I will show commands for SNMPv2c. The main difference between these versions is in security and in the messages that are exchanged.
The SNMP agent does not send a request message to the SNMP manager. It only sends trap messages in case a problem occurs.
There are two types of SNMP traps:
* Trap
* Inform. This type of trap message is not supported by SNMPv1.
SNMP agent sends trap packet like alarm message, then, it sends information about alarm or event through an InformRequest message. And the end, SNMP manager has to need to replay with InformResponse message.
For more information, you can see my articles about SNMP:
https://forum.huawei.com/enterprise/en/snmp-configuration-1/thread/755977-100181
https://forum.huawei.com/enterprise/en/snmp-configuration-2/thread/755979-100181
https://forum.huawei.com/enterprise/en/snmp-configuration-3/thread/755981-100181
https://forum.huawei.com/enterprise/en/snmp-configuration-4/thread/755983-100181
