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January 28th, 2025 10:56
VLT vs/and STP
Hi
While building the STP topology on the basis of the VLT-domain#1 (two S4148T-ON, OS10), I faced a lot of issues because of contradicting information provided in the OS10 Enterprise Edition User Guide:
- VLT domain priority (4096do not override Switch default STP priority (32768: Default priority). STP continues building it own tree on the basis of the default priority. VLT does not play a significant role in building the tree and, looks like, STP convergence happens without VLT participation.
- the command mentioned in the User Guide (spanning-tree priority <priority-value>) is not accepted. The workaround is to change the global switch priority with the command "spanning-tree rstp priority <value> (even if I use rapid-pvst).
Could any expert in this field explain the above mentioned findings? What could be wrong with my understanding of the Dell networks?
thanks in advance!
Vlad
DELL-Charles R
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January 28th, 2025 15:46
Hello,
Normally we don't support initial configuration, but I can give some pointers.
The primary-priority setting which is configured under vlt-domain is not related to spanning-tree priority. It is used to determine which VLT peer will be primary versus secondary during VLT election. The VLT peer with lower primary-priority will be elected as primary. Independent whether it is primary or secondary, both VLT switches are active/active both processing traffic.
On the second question, if you are trying to use rapid-pvst, which is “per-vlan” spanning tree, you will have to specify the priority “per-vlan”. All parameters are set “per-vlan”.
OS10(config)# spanning-tree vlan 1 priority 4096
If you want to use rstp, which has one spanning-tree domain (not “per-vlan”), then
OS10(config)# spanning-tree rstp priority 4096
We do have Deployment Services if you need that you can contact Sales for more information.