Essential SNMP Chapter 8: Polling

1
Essential SNMP Chapter 8 Polling Thresholds

• Polling
• Internal polling
• RMON
• Alarms ? Events ? Traps and logging
• External polling

2
Pollinglike checking your oil

• A physical process (e.g., SNMP get)
• Gauges/measures for OK, low, high . . .
• Frequencydepends on
• Importance of function tested
• Cost of doing the testing (includes bandwidth and
  CPU cycles)
• Technical measurement issues (dont poll averages
  more often than theyre calculated)

3
Internal polling

• A process run on the device itself
• Doesnt use bandwidth
• Doesnt even have to use SNMP polls
• Common approacha scheduled process/job that
  sends traps

Example http//linuxnt.bsunt.net/wikis/nt415/inde
x.php/Check4file
4
RMON (Remote Monitoring)

• RMON is like a self-contained mini-NMS on a
  device . . .
• That does internal polling on itself
• And can generate alarms
• . . . That can call events
• . . . That can sends traps and log internally and
  externally
• And can also respond to polls from an external NMS

5
RMON Alarm One
RMON Event One
RMON Alarm Two
SNMP Trap
RMON Event Two
RMON Alarm Three
Log
RMON Event Three
RMON Alarm Four
Modified Figure 8-1, RMON process flow (page 158)
6
Working backwards . . . Setting up events
alarms with Ciscos RMON

• Lets interpret these commands
• (config) rmon event 1 log trap public
  description High ifInOctets owner dmauro
• (config) rmon event 2 log description Low
  ifInOctets owner dmauro
• (config) rmon alarm 25 ifEntry.10.2 60 absolute
  \
• rising-threshold 90000 1 falling-threshold 85000
  2 owner dmauro

7
External polling

• Uses NMS and agents on separate machines
• Uses bandwidth
• Uses SNMP
• Requires coordinated configuration of NMS and
  agents

8
HP OpenView notes

• OKyou didnt memorize it all, but did you
  notice
• It has both GUI and command modes (why?)
• It makes graphing very convenient (why?)
• In addition to short-term graphs, it does
• Longer-term data collection (why?)
• Thresholding (what/why?)

9
Castle Rock SNMPc notes

• It does graphing also
• It does longer-term data collection also (and
  calls it trend reporting)
• It does thresholding also (and can have
  automatic alarms)
• Perhaps we will yet see more . . .