Network Management Strategies for the CIO
Change management
Scott M. Ballew
The best way to handle network problems is not to have them, as this tip says. But how can you ensure that you won't have them? Well, you can't. But because most network problems are caused by human errors, having a complete set of documentation on your network, as this tip, excerpted from
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Managing IP Networks with Cisco Routers, by Scott M. Ballew, published by O'Reilly & Associates Inc., suggests, is a way to help keep changes from messing you up, or of recovering with few problems, should problems occur.
The best way to handle network problems is to avoid them. The problem that you don't have to fix is the least expensive. Most network problems are caused by human errors, often by networking staff. Such problems can be physical, such as removing a connection in error, or they can be caused by configuration errors. Fortunately, these are also the easiest problems to avoid.
If taking notes while troubleshooting helps you avoid simply moving the problem around, consider how many problems you could avoid by keeping detailed records. For example, if your wiring closets and hubs all have accurate and complete records of what is connected where, the odds of removing a connection in error are much smaller.
So what kinds of records are necessary? First, you should an accurate and complete record of all physical connections in your network. It should be possible using these records and these records alone to physically trace a connection from any machine in your network to any other machine without leaving your office! These records should be detailed enough so that you can identify exactly which pair or wires of fibers connect two devices together, and they should identify the ports on any intermediate devices.
The second kind of records that you should keep is detailed change logs for all of your configurations. Ideally, these logs should show all lines or values added, changed and deleted for each configuration change, the date and time the change occurred, who made the changes, and a brief description of why the change was made. This information then gives you the opportunity to review changes, and can help you to determine whether the desired goal was met.
How long should you keep these records is a matter of taste, but the longer the better. I once was able to correlate a rather low-frequency intermittent network problem with a single Ethernet segment as it moved from one router to another over a period of two years, simply by reviewing the log of configuration changes for these routers. Fortunately, keeping such a change log need not be an involved task, and can be nearly automatic.
To learn more about Managing IP Networks with Cisco Routers, or to buy this book, click here to go to our online bookstore.
This was first published in April 2002
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