Getting The Most From SNMP


While you're planning your SNMP network management, you should think about the quality of network management you want to achieve. SNMP is a simple protocol, but that doesn't limit what you can do with it.

A well-designed SNMP system will support advanced network management features. This includes:

  • Detailed info about the state of every device on your network.
  • Precise location of where and when network integrity threats occur.
  • Remote operation of device controls.
  • Intelligent alarm management.

Features like these will make your network more reliable, decrease downtime, and improve network services. All of which will keep your customers happy and give you an edge on your competition.

But whether you can use all these features depends on your SNMP manager and proxy agent. Not all SNMP devices provide the same level of functionality. Understanding what the right SNMP gear can do will help you determine what management features you need to get the most from SNMP.

How SNMP manages detailed information

The real power of SNMP isn't its small command set, but the way it describes devices.

Each device in an SNMP network is defined by a data file called the Management Information Base, or MIB. The MIB defines the device as a set of managed objects- values that can be read or changed by the SNMP manager. Managed objects can include alarm elements, controls, device uptime, or other aspects of the device.

Device elements must be listed in the MIB for them to be visible to the SNMP manager. All SNMP devices support a generic MIB that defines generic traps. But, to use advanced network management features, you need to be able to use granular traps that contain device-specific info. Granular traps require detailed MIBs that fully describe the managed objects of your devices.

Manufacturers of SNMP devices create their own unique set of MIBs to include device info not listed in the generic MIB. Some manufacturers create more detailed MIBs than others, so your choice of SNMP gear directly affects how well you can manage your network.

The right proxy agent is key for collecting detailed network information

The MIB of your SNMP proxy agent, for example, determines how much visibility you'll have of your non-SNMP devices. Devices that weren't built for SNMP don't have MIBs of their own. They appear on the SNMP network only because their managed objects are listed in the MIB of the proxy agent.

If your devices contain elements that are not defined in your proxy agent's MIB, the manager will never see them or know about them, and you'll have no visibility of them. Imagine how disastrous this can be if a crucial object of a non-SNMP device-an analog temperature sensor, for example-isn't defined in the proxy agent's MIB.

To get the most complete view of your network, you must assess the non-SNMP elements you need to monitor. Then, choose a proxy agent that provides the best MIB support of them.

Detailed network management requires advanced SNMP managers, too

Being able to make use of info from your devices is just as important as being able to collect it. To get the fullest visibility of your network, your SNMP manager must be able to accept, interpret, display and process the info sent by the SNMP proxy agent.

If you need to manage data from an SNMP proxy agent, one of your most important requirements for an SNMP manager is full support for detailed, granular traps. Remember, granular traps require info defined in manufacturer-specific MIBs. Not all SNMP managers can accept granular traps. Mainly traps from proxy agents mediating non-SNMP devices.

Out of the box, many SNMP managers can accept only generic traps. Adding granular trap capability requires creating a special software module for the manager, at considerable effort-or expense-for the user. More advanced managers will have built-in support for granular traps.

Another feature to consider is how your SNMP manager handles undefined traps. Some SNMP managers will not display or log undefined traps, leaving you with no visibility of serious network threats. Your SNMP manager should display when and where undefined traps happen, or at least write them to a log file.

Your SNMP manager should also be able to import and compile manufacturer-specific MIBs. This feature will allow you to directly select the managed objects you want to be notified of and assign them severity levels. This will not only give you the greatest visibility of your network, but it will also increase the flexibility of your network management.

Merging SNMP and non-SNMP

A truly advanced SNMP manager isn't just for SNMP. For various reasons, you may want to bypass an SNMP proxy agent at some sites, while still integrating your network to a single manager. If so, you should look for a network management platform that can integrate SNMP and non-SNMP protocols on a single console.

Using one console will make your network management more reliable and less costly. You'll save on costs for gear, maintenance, and staff training. Your monitoring staff will not have to divide their attention between a lot of systems.

Intelligent alarm management

As we've seen, advanced SNMP gear can collect granular device data, display and process granular SNMP data, and even integrate SNMP with non-SNMP protocols. Having these capabilities will help you implement an intelligent alarm management system.

Intelligent alarm management does more than display network integrity threats - it processes alarm data to create complex automated responses when trouble happens.

An intelligent alarm management system can:

  • Automatically alert technicians of alarms by pager and e-mail.
  • Automatically alert backup technicians and supervisors if alarms are not acknowledged.
  • Create custom derived alarms from user-defined formulas.
  • Automatically control remote site gear for immediate correction of emergencies.
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