SNMP is a topic covered by most books about networking, so we do not discuss it here in detail. However, we can’t write a chapter on network monitoring without at least mentioning it. In a nutshell, SNMP helps you monitor the state of devices in the network.
The protocol supports both on-event and on-demand generation of
chassis state information. Event-triggered notices are called SNMP traps. Traps are triggered when
certain conditions, such as link failure, authentication failure, or
chassis restarts, occur on a managed chassis. The trap notifications are
sent to one or more defined host workstations or servers that have been
configured to receive the traps. Chassis state information can be obtained
on demand by using variations of
commands issued from host workstations or servers back to the managed
In this configuration sample, SNMP is enabled on router
r1. Some SNMP-driven management tools are able
to populate a GUI based on content within the
Get responses and the trap notifications. For
this reason, the administrator chooses to define a system name,
r1-J2350, and the location where the chassis
is physically sitting,
(arguably the friendliest city in the United States).
The administrator also defines two community strings,
private, to control SNMP access to the
chassis. A community string acts as a keyword of sorts, in that the host
systems must use it to run
Get commands on the managed device. Community ...