Simple Network Management Protocol (SNMP) is a "language" that allows different equipment on a network to talk to each other. SNMP communication is possible between SNMP-enabled devices that have different hardware and software.
The SNMP protocol makes it possible for your SNMP monitoring tools to identify equipment, monitor and manage your network performance, keep an eye on changes happening between your monitored devices, and even determine the status of your managed devices in real-time.
If you are getting started in the monitoring field, it's important to know some main points about SNMP to help you get the most out of your system.
So, let's dive in.
The SNMP architecture is simple as it's based on an agent-manager model. In this model, we have managed devices, agents, and the SNMP manager.
Managed devices are all of your network equipment that needs to be monitored and controlled. The agents are devices that collect and transmit information about managed devices. And the SNMP manager also called the master station, is the interface between your NOC staff and the network management system.
In a nutshell, your agent will collect information about the devices in your remote sites, and send all this data to your SNMP manager. The manager will, then, show the information to you in an intuitive way through user-friendly interfaces.
The SNMP protocol is effective in networks of all sizes, however, it's best suited for larger networks spread out across large geographic areas. With this protocol, you won't need to try to keep an eye on each screen for each device you have at your remote sites.
SNMP allows you to view, monitor, and control all your managed devices with one single interface.
Although it is a simple protocol, SNMP can do a lot to help you manage your network. The following points are just some of its abilities:
It gives you Read/Write abilities. This way you can, for example, reset passwords remotely.
It collects alarm reports into a log, which is useful for troubleshooting and identifying trends.
It allows for SNMP-enabled devices to send emails, text messages or other types of notifications to alert you about network alarms and other issues.
You can perform active SNMP polling (allows master stations to ask devices for status every few minutes).
There is also the unsolicited messages (Traps) feature, that lets devices send alerts to the SNMP manager regarding error conditions.
But what if you use DNP3 or another protocol in your network? You have SNMP-based equipment, but you don't want to manage a separate SNMP manager for those alarms. What can you do?
The answer, in this case, is an SNMP mediation device that can convert incoming SNMP traps into your desired protocol. This creates a smooth passthrough of alarm data and eliminates having multiple screens to watch.
Actually, I find many clients that actually view this feature as a positive because it reduces device count.
I was just visiting Jim, who works for a major power utility in the eastern United States. Their enterprise DNP3 manager requires a licensing fee based on device count. By mediating a wide range of SNMP alarms through their T/Mon master station (output as DNP3), only the T/Mon aggregator is counted as a "device" for licensing purposes. This dramatically reduces ongoing licensing expenses, to the point where the T/Mon became a no-brainer decision that paid for itself within a year.
Oddly, we've carved out a fair amount of business for ourselves from an unusual source. Believe it or not, there is substantial demand for converting SNMP traps "backward" into contact closures. This was something we didn't quite expect at first, because our job with RTUs normally revolves around the opposite: collecting contact closures and turning them into SNMP data over IP.
After a few probing questions, we've learned from my clients that the reason for their "reversed" application is simple: legacy fire panels.
These devices are legally mandated (or simply just what's still in use) and can only accept contact closures. Still, there's plenty of newer gear out at the site that only outputs alarms via SNMP.
This odd scenario is precisely how the "Trap Relay" line of DPS products was born. We're taking 8 or 32 or 64 SNMP traps (depending on model), identifying them uniquely from a user-specified list, then latching a corresponding relay. That creates the desired scenario: your fire panel is monitoring SNMP alarms in a way that complies with local ordinance and regulations.
There's no protocol that we see in use at client facilities more frequently than SNMP. If we visit a DPS client anywhere in the United States or in the world, the odds are high that they're monitoring SNMP.
That's because there's a tremendous amount of SNMP-based devices in use in telecom networks today. You can't ignore monitoring SNMP, because it's the only option for alarm reporting on many different pieces of gear.
Yes, some equipment can send an email alert or give you access via a web interface or proprietary software, but that only makes sense at small entities with 10 sites or fewer. Beyond that, you need a central master station - and protocol communications to send it data.
If you want to know more about SNMP implementation, we recommend our SNMP Tutorial White Paper. With it, you will have all the details to make SNMP monitoring easy and efficient. Download your free copy and start learning today.
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Download our free SNMP White Paper. Featuring SNMP Expert Marshall DenHartog.
This guidebook has been created to give you the information you need to successfully implement SNMP-based alarm monitoring in your network.
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