In school networks, ensuring low latency and optimising Round Trip Time (RTT) is crucial for delivering a seamless online learning experience. Latency refers to the delay in data transmission between devices, while RTT measures the time taken for a data packet to travel from the source to the destination and back. High latency and prolonged RTT can result in sluggish network performance, delays in communication and hindered educational activities. This knowledgebase article aims to provide IT admins with troubleshooting steps to identify and address latency issues effectively, ultimately improving RTT in school networks.
Measure and Benchmark Latency
Use network monitoring tools or specialised latency measurement tools to accurately measure latency and establish a baseline for comparison.
Benchmark the latency values against industry standards or established best practices to identify if the network's latency is within acceptable limits.
Network Traffic Analysis
Conduct a thorough analysis of network traffic patterns to identify potential causes of latency. Monitor network utilisation, identify bandwidth-intensive applications or devices, and assess their impact on latency.
Implement Quality of Service (QoS) mechanisms to prioritise critical network traffic and minimise latency for time-sensitive applications such as video conferencing or real-time collaboration tools.
Bandwidth Management and Allocation
Insufficient bandwidth can lead to increased latency. Evaluate the available bandwidth in your network and ensure it meets the demands of users and applications.
Implement bandwidth management techniques such as traffic shaping, bandwidth reservation, or dynamic bandwidth allocation to optimise bandwidth utilisation and minimise latency.
Network Infrastructure Optimisation
Optimise your network infrastructure to reduce latency. Consider the following:
Ensure switches, routers, and other network devices are properly configured and capable of handling the network load.
Implement a hierarchical network design that minimises the number of network hops and reduces latency.
Utilise spanning tree protocols (STP, RSTP, or MSTP) to eliminate loops and ensure a loop-free network topology, thereby preventing latency caused by broadcast storms and excessive traffic.
Quality of Service (QoS) Configuration:
Configure QoS settings on network devices to prioritise Vivi traffic and reduce latency for real-time applications.
Assign appropriate priority levels and bandwidth limits to different types of traffic, ensuring that Vivi receives sufficient resources.
VLANs and Inter-VLAN Routing:
VLANs are used to segregate network traffic into separate virtual networks, which can improve network performance and reduce latency.
Properly configure VLANs and inter-VLAN routing to ensure efficient communication between different network segments.
Ensure that VLANs are appropriately designed and implemented based on the school's network requirements and traffic patterns.
Monitor VLAN traffic and analyse any potential bottlenecks or misconfigurations that may contribute to latency.
Redundant Routes and Spanning Tree Protocols:
Here are some general best practices for configuring STP:
Understand the STP versions: Familiarize yourself with the different STP versions such as IEEE 802.1D (Classic STP), Rapid Spanning Tree Protocol (RSTP, IEEE 802.1w), and Multiple Spanning Tree Protocol (MSTP, IEEE 802.1s). Each version has its own features and considerations.
Configure a Root Bridge: Designate a root bridge within the spanning tree topology. This should be the most stable and reliable switch in your network. Configuring a root bridge helps ensure optimal spanning tree paths.
Use PortFast: Enable PortFast on access ports that connect to end-user devices. PortFast allows for fast transitioning of ports to the forwarding state, bypassing the listening and learning states. This helps reduce convergence time and avoids unnecessary delays.
Enable BPDU Guard: Enable BPDU (Bridge Protocol Data Unit) Guard on access ports to protect against accidental network loops. BPDU Guard automatically shuts down ports that receive BPDUs, indicating the presence of a switch or bridge.
Implement Rapid Spanning Tree Protocol (RSTP): If supported by your network equipment, consider using RSTP instead of the older Classic STP. RSTP provides faster convergence times, better loop prevention, and other enhancements.
Configure UplinkFast or BackboneFast: UplinkFast and BackboneFast are Cisco proprietary features that improve the convergence time of STP. UplinkFast enables faster transition of blocked ports to the forwarding state when an uplink fails. BackboneFast reduces the convergence time when indirect links fail.
Optimize STP Timers: Adjust the STP timers to optimize the convergence time for your network. Parameters such as Hello Time, Max Age, and Forward Delay can be tweaked based on network size, topology, and requirements. Care should be taken to ensure that timers are consistent across the network.
Implement Redundant Links: Utilize redundant links and implement link aggregation techniques such as EtherChannel (Cisco) or Link Aggregation Group (LAG) to provide higher network availability while preventing STP loops.
These are just a few general best practices for configuring Spanning Tree Protocols. It's important to consult the documentation specific to your network equipment and vendor for detailed instructions and additional recommendations.
As a more specific example, here are the best practices for configuring your spanning tree on Cisco networks:
https://www.ciscopress.com/articles/article.asp?p=2832407&seqNum=6
And here are some great spanning tree “gotchas” to look out for: https://www.auvik.com/franklyit/blog/spanning-tree-mistakes/
Network Latency Testing:
Perform regular network latency testing using specialised tools to identify bottlenecks and areas for improvement.
Simulate real-world scenarios and measure latency between different network devices or endpoints.
Take necessary actions to address excessive latency in specific devices or network segments.
Wi-Fi Optimisation:
Optimise Wi-Fi performance to reduce latency in wireless environments.
Ensure proper access point placement, configuration, and coverage to minimise interference and improve signal quality.
Implement Wi-Fi technologies such as beamforming or band steering to enhance signal strength and reduce latency.