work. Simple Network Management Protocol (SNMP) and Remote Monitoring
(RMON) provide much of this visibility. RMON is another method for obtaining
environmental and statistical information from devices. Much of the RMON
technology implementation is based on the deployment of RMON probes that
gather the information from the circuit (physical media) because the router or
switch may not support all levels of RMON information.
and error statistics, historical statistics, alarm notification, and event
logging. Additional monitoring may use the Switched Port Analyzer (SPAN)
function, which is also referred to as port mirroring. Cisco's SwitchProbe
product line can provide access to the other five layers of RMON in addition
to the RMON2 groups. Examples of the commands used to configure a
SPAN port appear later in this chapter.
Catalyst provides diagnostic information via LEDs on the line modules and
the Supervisor engine.
lem, including a broadcast storm or the need for review of the network design.
This set of lights is useful when troubleshooting in the main equipment room
or wiring closet.
indicate a failure.
Tree
network problems and are invisible to the administrator. This differs signif-
icantly from routers, which are visible through increments in hop counters