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The Most Valuable NMS Tool

I've been attending and presenting at Enterprise Connect for several years now and have collected several interesting tidbits along the way. One of the interesting discussions happened a couple of years ago when I was participating in a panel about network management tools for Voice and Video. Someone asked me what I thought was the best network management tool. I thought I'd share some thoughts along these lines in this month’s blog.

What's the Best Network Management Tool?
My somewhat flip answer to the question "What is the best network management tool?" was "The tool that you have and use regularly is infinitely more valuable than all the tools that you have but rarely use." It parallels a similar thought among photographers: the camera that you have with you to capture a scene is infinitely more valuable than the high-end camera that's sitting at home in the camera bag.

In Network Management, one of the key factors in a smoothly running network is detecting when the network is not running smoothly. You only know when it isn't running smoothly when you collect enough information to detect abnormal behavior.

A tool that automatically detects and reports on error-disabled switch ports allows you to develop a view of how smooth the network is running. If you follow networking best practices, you will have implemented various configuration parameters that protect the network from serious accidents like spanning tree loops. These configuration parameters might be LoopGuard or RootGuard on inter-switch links. You may also use BPDUGuard on edge ports to prevent an accidental loop creation when someone "cleans up loose cabling" by plugging a dangling RJ45 connector into a nearby wall jack, creating a spanning tree loop. Your tool should identify any of these things and after a while, you become accustomed to when and where such problems occur and their symptoms.

Tool Deployment
I favor network management tools that are easy to deploy. In my experience, big infrastructure tools take a long time to deploy and offer much less value than tools that are easy to deploy. If you are stuck with a corporate decision to buy and install a high-maintenance tool, select some basic functionality and get it implemented quickly, then move to more advanced functions.

Regardless of the type of tool, you should start with a focus on two general functions:

1. Event management;
2. Collecting basic interface performance stats, including in/out packets, in/out bytes, interface errors, discards, and overruns from all network interfaces.

Create reports and alerts for each function. I like to have an overall event management report generated daily to list a count of all event types that have been received. The daily event summary report indicates the types of problems that the network is detecting and reporting. The single critical event is just as important as the device that is constantly reporting a low-severity problem.

The interface stats report should include several Top-N reports on interface utilization, interface errors, and interface discards. This report allows you to identify interfaces that are congested or that are experiencing high numbers of errors.

After a few weeks of running the above reports, you will have a good idea of the problem spots in the network and the general health of your network. You can then start to implement additional functions, such as configuration backups, checking for correct router redundancy implementations, and identifying redundant interfaces that are not properly configured and working.

Next page: Management of Voice and Video

Management of Voice and Video
Once you have visibility into the operation of the basic network infrastructure, you can add functions specific to voice and video management. As with the network, I like to have tools that help identify problems. A simple delay, jitter, and loss report from the call controller system is useful for identifying phones or video endpoints that have recurring problems. A Top-N report for each of the operational parameters is very useful for easily identifying affected nodes. It takes a bit more work to identify the other endpoints and the path between the endpoints.

Also look at problems that affect the connectivity between the endpoints and the call controller. Endpoints must contact the call controller to initiate a call to another endpoint, so this is critical to establishing a call. But once the two endpoints have established a connection between themselves, the call controller is no longer in the picture and the path between the endpoints is used.

There is an exception for conference calls and calls when the two endpoints are using different codecs. These calls must use a media gateway to convert the codec data formats or to forward the audio/video stream to multiple recipients. In this case, the endpoints will be communicating directly with the media gateway for the duration of the call, so you will have a different path to monitor.

If you find that some number of endpoints or media gateways are reporting problems, you may need to use your network tools to try to identify where the problem originates. For jitter and packet loss, look for interfaces that report errors or discards. Discards occur when the interface is congested and may occur in bursts that are not very visible to network management tools that are collecting interface stats every five minutes. Identifying interfaces with discards is easier than trying to look for interfaces with high utilization. I've seen interfaces that reported less than 40% utilization but had significant packet loss due to congestion caused by the bursty nature of the traffic on them.

The Tool You Have and Use Daily
Almost any NMS tool provides the basic functionality to implement the above functions. Try not to spend all your time customizing the tool. Use it to identify problems, correct the problems, and make sure that the problems stay fixed. As you find and correct problems, the network will improve. It will have fewer problems that affect voice, video, and applications. You will then have time to work on network designs to support new business needs.