The Methodology Behind Troubleshooting Enterprise Networks: A Primer on Best Diagnostic Practices
Diagnosing and troubleshooting a network problem in an enterprise network can be a daunting task. With the potential for multiple branch offices, hundreds or even thousands of hosts, dozens of routers, switches, and servers, all with different vendors or firmware, and good old fashioned human error, knowing where to start is key in implementing a quick solution. There is an established methodology when it comes to diagnosing a large network problem, and following its guidelines will help administrators keep an organized approach to troubleshooting.
Knowing Where to Start
Prior experience with the network in question can aid administrators in finding the issue and fixing it. If the majority of network issues that arise during the operation of a network come from specific errors with a known fix, this will quickly give troubleshooting a “go-to” first choice for solving a problem. Even without familiarity with the network, a procedure can be adhered to that will help keep everyone involved on the right track.
The first and most obvious first step is defining the problem in order to troubleshoot network errors. If a user is unable to connect to a file server to access their work, that would define the problem. This initial step generally makes itself known simply by its nature. It’s rare to be called in for troubleshooting without a clear issue already presenting itself!
Next, gather information from the affected users or systems. In the above example about a user having trouble connecting to a file server, it would be worth the time to ask some basic questions. When was the last time the user was able to access the server? Has anything changed since then? Are other users also experiencing the same issue? If the problem is more widespread, it’s likely there’s an issue upstream in the network. If it’s isolated to just that one host, there probably isn’t a wider network issue that needs to be addressed. Gathering information might be one of the most important, and often overlooked, steps in troubleshooting a large network. The data and testimony gathered here can be used to guide administrators throughout the rest of the troubleshooting process.
Gathering Data with Ping and Trace Route
This is important enough to garner its own section. The ping and trace route tools provide much more information than their simplistic functions would imply. A large amount of data can be gathered for later analysis using just these two commands.
Using another example, let’s say that some users in one part of an office are unable to connect to the network. The ping command can be used to gather information and isolate the problem. This diagnostic tool works across the network layer and using this first can be attributed to the divide and conquer approach to troubleshooting. It simply sends a packet from the host machine to the destination. Keep in mind that some interfaces may have access controls or there may be a hardware/software firewall preventing pings from reaching a host, so this command can have its uses limited, particularly on incoming WAN interfaces.
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