Polling Intervals Explained: Finding the Right Balance for Your Network
How often should you collect metrics? The answer depends on what you're monitoring, how critical it is, and what resources you have available.
What Is a Polling Interval?
The polling interval is the time between consecutive data collection cycles. If you poll every 60 seconds, you get 1,440 data points per day per metric. Poll every 5 seconds, and that jumps to 17,280 data points - 12x more storage, processing, and network overhead.
The Tradeoff
Shorter intervals give you better visibility into brief events but cost more resources. Longer intervals are efficient but can miss short-lived issues entirely.
Recommended Intervals by Metric Type
| Metric Type | Recommended | Rationale |
|---|---|---|
| Interface bandwidth | 60 seconds | Good balance for traffic trends |
| Interface errors/discards | 60-300 seconds | Errors accumulate over time |
| CPU/Memory utilization | 300 seconds | Changes slowly, less frequent OK |
| Device availability | 60-120 seconds | Balance detection vs overhead |
| Critical links | 15-30 seconds | Fast detection is priority |
| Environmental (temp) | 300-600 seconds | Changes very slowly |
Impact on Detection Time
Your polling interval directly affects how quickly you detect issues. With a 5-minute interval, a link could be down for 4 minutes 59 seconds before your first failed poll:
| Interval | Best Case | Worst Case | Average |
|---|---|---|---|
| 15 seconds | 0 sec | 15 sec | 7.5 sec |
| 60 seconds | 0 sec | 60 sec | 30 sec |
| 300 seconds | 0 sec | 5 min | 2.5 min |
Tip: Add retries and timeout to your calculation. With 60-second polling, 5-second timeout, and 2 retries, worst-case detection is 60 + (3 × 5) = 75 seconds.
Adaptive Polling Strategies
Smart monitoring systems adjust polling based on conditions:
Time-Based Adjustment
Poll more frequently during business hours (every 30s) and less at night (every 5m). Match your monitoring intensity to when issues matter most.
Threshold Triggers
When utilization exceeds 80%, automatically increase polling frequency. Get detailed data when you need it most.
Failure Backoff
When a device is unreachable, reduce polling to avoid wasting resources. Resume normal rate once it recovers.
Criticality Tiers
Core routers at 15s, distribution at 60s, access layer at 5m. Allocate monitoring resources where they matter.
Resource Considerations
Shorter intervals cost more across multiple dimensions:
- -Network load: SNMP packets consume bandwidth. 100,000 OIDs polled every 60s generates ~2-3 Mbps of SNMP traffic.
- -Device CPU: Every SNMP request requires the target device to gather and return data. Heavy polling can impact underpowered devices.
- -Storage: 12x more data points means 12x more disk usage (before compression).
- -Collector resources: Processing more metrics requires more CPU and memory on your monitoring servers.
Polling vs. Streaming Telemetry
Traditional polling has the collector request data. Streaming telemetry flips this - devices push data continuously.
| Aspect | Polling (SNMP) | Streaming (gNMI) |
|---|---|---|
| Resolution | Seconds to minutes | Sub-second possible |
| Device support | Universal | Modern devices only |
| Configuration | Simple | More complex |
| Scalability | Collector bottleneck | Better at scale |
For most networks, SNMP polling at 60-second intervals remains practical and effective. Streaming telemetry adds value for latency-critical applications or massive scale.
Finding Your Optimal Interval
Start with these questions:
- 1.What's your SLA? If you promise 99.9% uptime (8.7 hours/year), you need to detect outages faster than 5-minute polling allows.
- 2.What's the failure mode? Slow degradation (capacity planning) tolerates longer intervals. Sudden outages need fast detection.
- 3.What resources do you have? 15-second polling everywhere is ideal but may exceed your infrastructure capacity.
- 4.How long do issues typically last? If problems persist for hours, 5-minute polling catches them. If they're 30-second microbursts, you'll miss them entirely.