What is the best way to configure Spanning Tree Protocol (STP) in LAN switching?

Configuring Spanning Tree Protocol (STP) in LAN switching involves ensuring network stability and redundancy while preventing loops. 1. Enable port fast feature on the access port 2. use PVSTP for better load balancing and efficiency. 3. Use MSTP if available it provides both performance and efficiency. 4. Also enable BPDU gaurd on the access ports 5. Choose root of your choice on per vlan basis by varying priority.

Configuring Spanning Tree Protocol (STP) in LAN switching demands careful planning. Opt for a suitable version like RSTP for faster convergence. Designate a stable switch as the root bridge for an efficient topology. Implement features like Portfast to reduce downtime and BPDU Guard to prevent accidental switch connections. Use Loop Guard to prevent alternate ports from becoming designated during failures and Root Guard to maintain the root bridge integrity. Exercise caution with BPDU Filtering, as misconfiguration can disrupt STP. Ensure proper configuration of EtherChannel to avoid loops. Monitor STP operation, set up alerts, and maintain comprehensive documentation. Regularly test the network's response to failures.

It is also essential to consider UDLD and how this works with STP in an environment with multiple uplinks especially if you cannot manage the upstream infrastructure.This could quickly become quickly become a nightmare but one that can be managed with a proper architecture.

STP in today's deployment (2023) should be eliminated using technologies like vPC (or) MLAG. It is important to us all interfaces available in the forwarding plane rather than having an forwarding capable interface in blocked state (which IMO, is inefficient use of networking resources). If you have a platform which does not support technologies like vPC and MLAG convergence via PVST is the best way to optimize and use all the links available for forwarding.

There are differences between PVST (Per VLAN Spanning Tree) and non-PVST. With non-PVST where multiple VLANs share a single Spanning Tree, a blocking state on a port to prevent a loop in VLAN A may break the connection in VLAN B because those VLANs do not necessarily exist on all the links. For example, 3 switches are connected to each other. Each switch has two ports connecting to its neighbors. VLAN A exists on all 3 links while VLAN B only exists on 2 of them. To prevent the loop in VLAN A, a port will be placed in blocking state. But there is no loop in VLAN B since it only exists on two links. If the blocking port happens to be a forwarding port for VLAN B, the connectivity in VLAN B will be broken.

Though with modern stacking/virtualization technologies STP should not be used, I would still enable it, at least at the access layer. This would prevent local loops that could impact network performance and stability. STP has been guaranteeing redundancy and stability of networks for years and I wouldn't demonize it, if well designed and configured it still works well. In my experience I often found scarce knowledge of STP (in all its versions) which led to instability and poor performance. Anyway, I would never use proprietary versions, for most customers they are difficult to integrate with standard versions and in case of large networks with high numbers of VLANs they are resource intensive with impacts on the overall performance.