Network Monitoring with Paessler PRTG

If you’re interested in deploying PRTG in your environment, or getting help with an existing installation, let us know!

What can I monitor with PRTG?

PRTG can monitor infrastructure of virtually any size, from a single office network with just a few workstations to thousands of disparate devices scattered across the globe. There are pre-built sensors for most brands of computer and network infrastructure, and with robust support for custom sensors, practically anything can be monitored. Products like the Paessler Building Monitor further expand the potential uses, offering smart-home-like insight and automation to commercial buildings and factories.

What's the difference between PRTG Ntework Monitor and PRTG Enterprise Monitor?

In a word, licensing. All PRTG licenses are sold on a per-sensor basis, but there’s a little more to it than that.

PRTG Network Monitor licenses entitle you to a single core installation plus one failover core for life, plus updates and support for a specified period (or with ongoing maintenance purchases), with a hard limit on the number of simultaneously active sensors.

These licenses start at 500 sensors and scale up to 5,000 or even unlimited (constrained only by the hardware it’s running on) sensors.PRTG Enterprise Monitor licenses are designed for large environments. They start at 20,000 sensors, and entitle you to an unlimited number of installations, allowing for much greater distribution and redundancy. Enterprise also comes with the addition of the ITOps Board, providing a single-pane-of-glass overview of the entire environment across multiple cores. Unlike PRTG Network Monitor, these are not perpetual licenses, but as a result both support and updates are included for the full subscription duration.

Is this a cloud-hosted service?

As a rule of thumb, companies with this kind of monitoring need typically also have the infrastructure to host PRTG themselves; correspondingly, the overwhelming majority of licenses are on-premise.

For customers with highly distributed infrastructure, or few to no on-premise servers, Paessler offers PRTG Hosted Monitor as a cloud-hosted option, but it comes with the caveat of a maximum of 10,000 sensors, and therefore only one PRTG instance.

What is the best way to monitor a large number of devices?

A successful large PRTG deployment starts with a thorough understanding of the environment and monitoring goals, and PRTG’s capabilities and limitations. Dreadnought was the first company in the US to achieve Paessler Certified Implementation Engineer status, and is uniquely positioned to help ensure a smooth, scalable, and effective PRTG deployment.

For those handling implementation in-house, we strongly suggest reading:
Planning large installations of PRTG Network Monitor.

In general, Paessler recommends a maximum of 10,000 sensors per core, or half that number for 2-core failover clusters. That number can vary substantially depending on the hardware hosting the installation, and the sensor composition. Effective use of remote probes can help alleviate the bottlenecks of highly resource-intensive sensors, dramatically improving scalability. For environments with more than 10,000 sensors, it often makes sense to deploy more than one core, so PRTG Enterprise Monitor may be a better fit.

Once your cores are set up and devices are onboarded, the next challenge is to prevent the large environment becoming overwhelming. Here are a few things we recommend spending time on to maximize the value of a PRTG installation:

Set reasonable warning and error thresholds
Configure sensor dependency to reduce notification flood when major infrastructure is degraded or offline
Customize alert templates to include troubleshooting or resolution steps and escalation points of contact
Build meaningful maps to provide instant visual feedback on overall status and the impact of any alerts
Deploy the ITOps Board for even broader visibility into multiple installations

I see SNMP and WMI sesnor options for the same type of data. Which should I use?

New PRTG users tend to gravitate towards WMI sensors for a few reasons, the most common of which are Windows nativity and the ease of deployment courtesy of AD credentials. That usually works out fine for overloaded IT staff at the SMB scale, but in larger deployments the performance penalties of WMI start to add up. Paessler recommends a maximum of 200 WMI sensors per probe, whereas cores running exclusively ping and SNMP sensors can scale well beyond the recommended total sensor count per core without performance issues. Fortunately, SNMP provides very similar monitoring capabilities on Windows servers, especially for fundamental resources such as CPU, disk, memory, and network. This table outlines the major differences between the two in both implementation and ongoing monitoring:

SNMP Pros:
More scalable (much greater parallelization than WMI)
Reduces remote probe count (i.e. VM resource consumption)
Consistency across (non-)
Windows monitoring

WMI Pros:
Native (simple deployment)
Active Directory authentication
WMI multi-disk sensor reduces sensor count (and license costs)
More detailed statistics for processes

SNMP Cons:
Requires additional configuration on Windows hosts
No SNMP multi-disk sensor (increases sensor count)
Process monitoring in Windows only running or not, no CPU/memory usage

WMI Cons:
Resource-heavy for device, probes, and cores
Low (200) limit on sensors per probe
Higher network load
Requires special permissions or scripting for process monitoring
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When discussing SNMP, it’s worth mentioning that SNMPv2 is far and away the most efficient meaningful sensor (excluding perhaps ICMP ping) available in PRTG. SNMPv3 comes with encryption, increasing the CPU overhead of each query on both the probe and device, and reducing the overall scalability in the process. But no matter which version of SNMP is employed, the performance impact is still lower than WMI.

Of course, it’s entirely possible to mix-and-match even on the same device. For example, a single Windows server could have SNMP CPU, disk, and process sensors, but use WMI to check update status, which would still be far more scalable than querying all of those resources via WMI exclusively.

‍Our recommendation is to use SNMP wherever possible, and fall back to WMI as needed in order to meet specific monitoring requirements SNMP cannot.

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