Hello @13jobsp90
A careful approach is needed to avoid potential disruptions...
With your infrastructure comprising two core switches in HSRP, two distribution switches, and cascaded access switches connecting various devices across multiple VLANs, there are several critical factors to consider.
First, in a hierarchical network, your core switches should serve as the root bridge for each VLAN to maintain optimal traffic flow and prevent inefficient routing. Since your core switches are running HSRP, ensure the primary core switch is the root for all VLANs, with the secondary core switch configured as the backup. This alignment with HSRP will help ensure traffic flows through the shortest paths. Set spanning-tree priorities on the core switches to establish primary and secondary roots, using lower priorities on the designated primary core switch and slightly higher priorities on the backup core switch.
One of the benefits of RPVST is faster reconvergence, which can also mean that any network instability could propagate quickly !!! To mitigate potential issues, enable Loop Guard on all trunk ports that do not act as the root ports. This will prevent potential network loops if an issue arises with root or designated port roles. In addition, BPDU Guard should be activated on ports connected to end devices, which will ensure that unexpected BPDU packets from devices like IP cameras, phones, or PCs do not interfere with your spanning-tree topology. Considering that you have configured these access ports as spanning-tree portfast...enabling portfast on these edge ports will reduce convergence delays. Ports with portfast configured transition immediately to the forwarding state, allowing devices to connect more quickly. However, BPDU Guard should also be enabled on these edge ports to automatically disable them if a BPDU is detected, which could indicate an accidental loop created by connecting a switch or bridge.
As your network has VLANs configured across multiple devices, ensure consistency across VLAN configurations before beginning the transition. Use commands like `show vlan` and `show spanning-tree vlan` to confirm all VLANs are properly configured across core, distribution, and access switches. For trunk links, manually prune unused VLANs to reduce unnecessary traffic, which will optimize bandwidth across your network.
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Start by enabling RPVST on the core switches, then the distribution switches, and finally the access switches. Monitor the network for any unexpected blocking or changes in root and designated port roles. By testing each section of the network individually, you can isolate and resolve any issues before fully deploying RPVST.
!!! For a production network, it’s best to make this change during a maintenance window !!!
Once RPVST is active across your switches, keep a close watch on your spanning-tree status for a period to catch any potential issues early. Regularly use `show spanning-tree` commands to check root port status and confirm that all devices are functioning correctly. Having backups of your configurations will be beneficial if a rollback is required...
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Here are some key commands to support your RPVST transition.
--set Root Priority for Cores
spanning-tree vlan <VLAN_ID> root primary
spanning-tree vlan <VLAN_ID> root secondary
--enable PortFast and BPDU Guard on Access Ports
interface range <port_range>
spanning-tree portfast
spanning-tree bpduguard enable
--enable Loop Guard on Trunks:
interface <interface_id>
spanning-tree guard loop
-verify spaning tree config and status:
show spanning-tree summary
show spanning-tree vlan <VLAN_ID>
Best regards
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