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Performance degradation, the top 10 causes for network slowness

Diagnosing network performance issues is part of your daily work. Whatever the network diagnostic tools you use, it is important to understand what are the symptoms of network performance degradations and what are the most likely root causes for them. 

Accelerating troubleshooting operations is key to maintain the business productivity through excellent end-to-end user performance rates. 

Symptoms of a performance degradations

symptoms of performance degradations
How can you notice that the network performance is degraded?
You may use a variety of tools to run your performance troubleshooting (from network monitoring tools using SNMP polling platforms to packet analyzers such as Wireshark). Here are the 4 main symptoms you encounter:
  • Slowdown

    • Either your monitoring tools are reporting an increase in the network latency (either through ICMP testing like Pings or by measuring TCP connection times),
    • Or your users for a given network location report a network slowdown.  
  • Disconnections

    • You notice that some clients get disconnected from the applications or the network. They can reconnect afterwards. 
  • Outage

    • The network services and / or the applications become unavailable for some users at a given point of time. 
  • End user complaints

    • You get reports from the helpdesk that users are complaining about slow response times, but they do not provide enough details to identify the scope of the slowdown (when? which application? for which transaction? etc...). 

PerformanceVision can help you track performance rates across your infrastructure. If you would like to learn how to accelerate your network and application performance troubleshooting, please register to this 30-minute webinar

Webinar Accelerate performance troubleshooting

What are the most likely root causes for network performance issues?

This list is the starting point of your network performance checklist with all the potential causes you should eliminate or validate to identify the root cause of your network trouble.  

  • Hardware failure

    A cable has a defect on the client-end, server-end, cable patching level (as a simple example, due to the patch cable density, a cable disconnects under the weight of others, generating intempestive disconnections for a given server). 
  • Configuration of a network switch

    A defective configuration induces packet loss, like bad interface negotiation, physical errors, etc.. 
  • Network loop

    To learn how to identify a network loop, follow me!
  • Bandwidth congestion

    The quantity of data sent to / from a given destination exceeds the network capacity; this can be generated by business applications, as well as unwanted usage (such as web-browsing, backups / updates outside of the normal time-window, etc...). 
  • Network latency increase

    The time which is necessary to send the packets through the network has increased due to a change in the route / path or a defective network device. 
  • Shaping / Optimization / Filtering device

    Applying QoS settings slowing down the transfer or the network capacity which is available for a given application or simply resetting / blocking connections. 
There may be also other causes which are not network-related like: 
  • Host resource outage

    On the client or server side:  disconnectionsdue to resource outage or reducing the data transfer speed (As an example, a client or server, who runs out of system resources, is sending out "O-Windows" to slowdown the transfer; you can read more about this here)
  • Application server processing time

    Your server takes too long to respond either for all requests or only certain requests. It is very easy to detect this, click here to know how!
  • The quantity of data

    Sent and received by the application is large and takes too much time to transfer through the network (as an example, this may be due to a configuration or an application with a defect which sends an excessive data set to a client. Here is a concrete case presenting a diagnostic for such a performande degradation:  7 easy steps to troubleshoot the performance of a database-driven application
  • Name Resolution Service

    Your DNS server may respond too slow or your client may first request to a wrong server before querying the right one, etc... If you would like to learn everything you must about DNS and performance, you must read this article!

  • Authentication service

    Your authentication server is responding too slow. 
  • Application errors 

    Your application is generating errors for certain requests on the front-end or back-end servers. Tracking application transactions from the network traffic can be easy; to discover how you can do that: read this paper.

To learn how to troubleshoot network and application performance degradations in 4 easy steps, you can download our Performance Troubleshooting Guide: 

Performance Troubleshooting Guide

Topics: performance troubleshooting, NPM, network performance, Network troubleshooting

Posted by Ludovic Binther on 10 juin 2016
Ludovic Binther

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