GE S2020, Техническое руководство, Страница: 52 / 302

Chapter 4
– Functions
GE Reason Switches
52 REASON SWITCHES-TM-EN-3
Figure 9: Example of the SNMP management architecture
General operation is based on GET and SET requests, done by SNMP manager to the
agents. In this operation, the manager will poll information from the agents
periodically, apart from the information that is received at the time it occurs.
Examples like Link up, STP protocol information or switch Cold Start can be sent by
SNMP agents without a request from the server. The last type of operation is called
the Trap, and an asynchronous message received from an agent is called Trap
message.
When SNMP information must be sent through the network, the agent will search at
its own library of SNMP protocol information to search whether the request done by
the manager can be satisfied. An Information library is called Management
Information Base (MIB). Both manager and agent must have MIB libraries at its own
hardware to understand the information exchanged between them. When it comes
to Trap messages, there are some MIB libraries that can be set to be sent without the
request from the manager.
SNMP messages are exchanged in an IP network, generally using UDP transport
protocol. UDP port 161 is used to send request messages, and UDP port 162 is used
for traps.