The Network Layer
Besides revealing whether the switch is available or not, the tests mapped to the Network layer also indicate how well the interfaces supported by the switch are performing (see Figure 1).
The external agent monitoring the switch first polls the management module of the SNMP MIB-11, which in turn provides the details of all the other modules, their community strings, etc. Using this information, the agent then contacts the other modules, discovers the network interfaces supported by the switch, and then extracts key statistics pertaining to the availability and speed of each of the network interfaces.
As enough has already been said about the Network test and the Device Uptime test, let us just focus on the Core Builder test in Figure 1.