Licensing guide
Device licensing vs sensor licensing for network monitoring
Network monitoring vendors all say “simple pricing.” They do not all meter the same object. This guide defines each meter, shows how a single 24-port switch is counted, and works three public 2026 list prices.
Three meters show up in almost every NOC quote:
- Per device / per IP / per node — one license unit per thing with an address.
- Per sensor / per element / per interface — one license unit per check, port, or volume.
- Per module — base monitor is cheap; NetFlow, NCM, APM, and HA are separate SKUs.
The invoice follows the meter, not the marketing site. Product context for ZenPlus comes last.
Definitions
What each meter counts
Device / node / unique IP
One router, one switch, one server, one firewall. Interfaces, disks, and services on that box are usually included. Nagios XI nodes, WhatsUp Gold devices, and ZenPlus unique IPs work this way. The risk is not port sprawl. The risk is a second product when you need flow or config.
Sensor / element / interface
One ping, one CPU, one disk, one port. Paessler PRTG is the clean example: a sensor is one monitored aspect, and Paessler’s own guidance is about 5–10 sensors per device and one sensor per switch port. SolarWinds NPM’s older element model (largest of nodes, interfaces, or volumes) is the same family of problem: a well-monitored access layer burns elements.
Module
The base SKU does SNMP. NetFlow, config backup, and APM are add-ons. ManageEngine OpManager is the usual example. SolarWinds NPM + NTA + NCM is the suite version of the same idea.
Worked example
40 access switches + 10 routers + 20 servers
Estate: 70 devices, 40 of them 24-port switches.
| Meter | How 70 devices are counted | Published 2026 list |
|---|---|---|
| Sensors (PRTG rules of thumb) | 40 × 24 port-traffic sensors = 960; 40 × 3 device sensors = 120; 10 routers × 8 = 80; 20 servers × 6 = 120. ≈ 1,280 sensors | PRTG 2500 at $742/mo paid annually = $8,904/year (paessler.com/pricing). Vendor-described as “about 250 devices.” You have 70. The extra cost is ports. |
| Unique IPs (ZenPlus Professional) | 70 × $5 × 12. Every switch port included. NetFlow and NCM included in Professional. | $4,200/year (zentryc.com/pricing) |
| Modules (typical Orion / OpManager) | Start with a base NPM/OpManager number, then add NTA/NetFlow and NCM as line items. The 70-device SNMP quote is not the number that hits procurement. | Ask for the stacked quote, not the base SKU. See SolarWinds and ManageEngine. |
| WhatsUp Gold devices | Per device, unlimited aspects. Scale past the starter SKU is a quote. Traffic analysis / configuration management sit in higher editions. | Business starts at $1,229/year for 50 devices (whatsupgold.com/pricing). Compare the edition that matches the stack you actually run. WhatsUp Gold alternative. |
PRTG, WhatsUp, and ZenPlus figures are published USD list as of August 2026. Always re-check vendor pages before a purchase decision. SolarWinds Observability Self-Hosted public list (August 2026): Essentials $8, Advanced $14, Premier $17.50 per node/mo. Apples-to-apples vs NPM+NTA+NCM is Advanced $14 (includes flow + config management). Same 70-device estate at Advanced list: 70 × $14 × 12 = $11,760/year.
Procurement
How to read a vendor quote in 10 minutes
- What is the unit? Device, sensor, element, point, or flow source.
- What happens when we monitor every switch port? If the answer is “more units,” model the access layer, not the core count.
- Is NetFlow a SKU? If yes, add it before you compare.
- Is config backup a SKU? Same.
- Is HA a SKU? Same.
- Is the number on a public page or a quote? Public pages you can re-check. Quotes expire.
Where ZenPlus sits
Per unique IP, unlimited interfaces, on-premises
Professional includes NCM and NetFlow. Details on pricing, the PRTG alternative, the WhatsUp Gold alternative, and the Datadog alternative.
FAQ
Common licensing questions
Related: On-prem vs SaaS network monitoring · How to analyze firewall logs · AI incident triage for NOC · ZenPlus
Next step
Bring a device count. Get a per-IP quote.
Send the unique IPs you monitor and the tool you run today. We will return a like-for-like comparison against your current meter.