Cambium Test Cambium Performance Tracking 3 — Questions and Answers
Question 1: What Cambium tool provides SNMP-based polling for real-time performance data collection from PMP APs?
- cnMaestro with SNMP trap receivers
- Cambium Wireless Manager (CWM) (Correct answer)
- ePMP Spectral Analyzer
- cnReach Configuration Utility
Correct answer: Cambium Wireless Manager (CWM)
Cambium Wireless Manager (CWM) historically used SNMP polling for real-time performance collection from PMP access points.
Question 2: In ePMP performance monitoring, what does 'Downlink Efficiency' measure?
- The ratio of useful payload bytes to total bytes transmitted including overhead (Correct answer)
- The number of SMs receiving maximum MCS
- Total bytes received divided by channel width
- Percentage of time the downlink slot is active
Correct answer: The ratio of useful payload bytes to total bytes transmitted including overhead
Downlink Efficiency captures how much of the transmitted data is actual payload versus protocol overhead and retransmissions.
Question 3: Which cnMaestro alert condition most directly warns you of a performance degradation before users notice dropped throughput?
- High airtime utilization threshold breach (Correct answer)
- SM reboot event
- Certificate expiration warning
- Firmware version mismatch
Correct answer: High airtime utilization threshold breach
High airtime utilization is a leading indicator—it shows the sector is approaching capacity before users experience measurable throughput drops.
Question 4: On a PMP 450i AP, what performance statistic directly reflects the quality of the GPS timing source used for frame synchronization?
- GPS Timing Pulse Accuracy (PPS error) (Correct answer)
- Registered SM Count
- Downlink Data Rate
- Receive Power Average
Correct answer: GPS Timing Pulse Accuracy (PPS error)
GPS PPS (Pulse Per Second) error indicates how precisely the AP's frame timing aligns with the GPS reference, which directly affects synchronization quality.
Question 5: When analyzing cnMaestro throughput graphs, a regular saw-tooth pattern in downlink throughput most likely indicates what?
- Periodic interference or scheduled traffic shaping cycles (Correct answer)
- Normal ePMP TDD frame cycling
- Hardware memory leak in the AP
- SM firmware auto-update reboots
Correct answer: Periodic interference or scheduled traffic shaping cycles
Regular saw-tooth patterns in throughput graphs typically point to cyclical interference events or traffic shaping policies operating on fixed intervals.
Question 6: What is the recommended MIB object to poll for monitoring ePMP subscriber module receive signal strength via SNMP?
- cambiumSMRxPower in the ePMP MIB (Correct answer)
- ifInOctets in the standard interfaces MIB
- sysUpTime in the SNMPv2-MIB
- ipForwDatagrams in the IP MIB
Correct answer: cambiumSMRxPower in the ePMP MIB
The cambiumSMRxPower object in Cambium's proprietary ePMP MIB provides the SM-specific receive power value not available in standard MIBs.
Question 7: In a PMP 450 deployment, which performance metric should be tracked to detect gradual antenna degradation over months?
- Long-term trend of average SM receive power with no environmental changes (Correct answer)
- Daily reboot count
- Total data volume transferred
- Number of active SMs per sector
Correct answer: Long-term trend of average SM receive power with no environmental changes
A slowly declining trend in average SM receive power under stable environmental conditions is a reliable indicator of antenna or RF component degradation.
Cambium Test Cambium Performance Tracking 3
What Cambium tool provides SNMP-based polling for real-time performance data collection from PMP APs?