Troubleshooting Intermittent Network Issues

Apr 1, 2020

Here’s a situation familiar to every system administrator. An employee tells you that they can’t always use some of the services in the network. However, they can’t give you any specific data, such as the exact time at which they couldn’t access which service or whether the same server connection was always concerned.

How can you tackle this problem? By using the Allegro Network Multimeter, you can narrow down the cause of the malfunction within a matter of minutesand then take measures to correct it.

First search for the user via the browser-independent web interface. This is done intuitively by entering the user’s name into the full-text search in the IP address list within the central IP section. Matching computers are immediately displayed.

Click to select the computer of the employee concerned. The detailed view which now opens contains plenty of information broken down into different tabs. Go to the overview page and inspect the faulty server connections.

These ‘invalid connections’ are shown in blue in the graph ‘New TCP connections’. By default, the current server connections are displayed. If you zoom out, the time interval expands to show the past few hours. An especially large number of faulty server connections occurring at certain times are immediately apparent.

Pinpointing faulty server connections 

To examine the untreated server connections more closely, clicking on a peak limits the time range to this time interval. Similarly, zooming in a few times enables a very short interval to be displayed.

Switching to the ‘Peers’ tab now allows you to see the servers contacted in the time interval concerned. Sort them by ‘invalid connections’ again to immediately see the servers with the most errors (see screenshot). For a more detailed look at why server connections aren’t working, you can now create and download a pcap from the ‘packet buffer’ for the selected period and IP pair.

Hence, despite vague user information, you can still identify the affected server in a matter of seconds and examine the malfunction in detail using the isolated network traffic.

Related Solutions

For more information on Enterprise Network troubleshooting please visit these pages:

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