Detecting network bandwidth issues through congestion management.
Check the network:
- Monitor the helpdesk cases raised in particular where users are reporting problems with applications across the network. Knowing whether this is from a branch, remote site or from home (will shorten troubleshooting), it is likely to indicate network congestion.
- Monitor utilisation of network links and raise alerts when bandwidth becomes heavily utilised.
- Make sure you monitor packet discards and errors.
- And finally, monitor Quality of Service (QoS) parameters available in the network device; in particular, you are looking for where QoS caused packet loss.
The first step to detection is to get NMIS installed and let it start collecting data NOW. DOWNLOAD NMIS
Diagnosing Network Bandwidth Issues
By monitoring the network for issues related to congestion, you are ready to start further diagnosis to determine what is causing those issues and look for possible solutions to avoid the congestion firstly or control it secondly.
Depending on the tools available to you, you should have an idea of those causes. For example, putting aside transmission, format errors, or device health issues packet discards will generally be caused by QoS classes dropping packets, so the solution is to refine the QoS configuration to prevent the desired traffic from being discarded.
Depending on the application, the dropped packets will be causing retransmissions if they are using TCP, while voice and video symptoms are voice clipping or slow refreshing video or video and voice not keeping sync.
Depending on the devices and operating systems being used, you should be able to see key performance indicators for this, which will be collected by your monitoring system, like NMIS. For example you could monitor for TCP retransmissions on servers, this would indicate issues with those applications.
Using systems like Cisco IPSLA are a great way to monitor for changes in latency or variability in latency (Jitter). NMIS can collect your IPSLA data, providing graphs as well as alerts when it detects issues.
Monitoring these metrics will guide where you need to look deeper, you might need to collect more detailed information from the devices to determine what the issues are, e.g. looking at command outputs for QoS or interface information to decide what changes are available to resolve the helpdesk reports.
If you identify the QoS Classes which are exceeding their configuration limits with resulting packet loss, you will need to consider changing the bandwidth allocations for those classes, increasing the available bandwidth for voice and video, for example.
OPA can help with the detection and diagnosis of congestion problems.
Actions to fix network bandwidth problems
Contrary to popular belief, QoS does not create more throughput. It does create better “goodput,” with critical applications protected, and applications that are hogging bandwidth, controlled.
Two standard policy options for QoS are shape or police. Policing will ensure bandwidth is never exceeded and drop the offending traffic. Shaping will delay traffic to smooth out the traffic over time. Note that as shaping limits are exceeded, it may result in dropped traffic.
Talk to us about how our solutions can give you the insight you need to make data-based decisions. You’ll reduce helpdesk stress, own your infrastructure all while improving the user experience.