The results of the tests shown in the table below, prove that the spanning tree implementations with particular configurations can be seamlessly integrated into an existing environment so long as a clear understanding of the implementation is obtained before doing network migration.
Although running a mixed spanning tree environment is not recommended, it is good to know that SmartFabric OS10 spanning tree options and device redundancy features provide solid performance and interoperability capabilities. Based on the test results, matching the spanning tree mode is the most efficient and recommended type of deployment.
Dell EMC | Cisco | Behavior |
RPVST+ | RPVST+ | Same mode, 100% interoperable. Both spanning tree modes use the same convergence timers so the convergence times upon link failures are quick. Traffic converges in both the RPVST+ instances. |
MST | MST | Same mode, 100% interoperable. Convergence takes place. |
RSTP | RPVST+ | RSTP instance of OS10 converged only with RPVST+ instance of VLAN1 in Cisco. |
RSTP | MST | RSTP instance of OS10 converged with MST Instance 0 in Cisco. |
RPVST+ | MST | VLAN 1, the default VLAN in OS10 converged with mst0 in Cisco. All other VLAN instances in RPVST+ and other MSTI in MSTP do not converge. |
MST | RPVST+ | Only mst0 in OS10 converged with RPVST+ VLAN 1 instance in Cisco. For VLAN 1, both the switches interoperate and agreed on the root bridge. |
RPVST+ | PVST+ | OS10 RPVST+ is interoperable with CISCO PVST+. Convergence takes place (supported releases 10.5.21 or later) |
With VLT: RSTP | With vPC: RPVST+ | Most efficient and simpler deployment due to the back to back port channel links between both logical domains. It requires that both switches have a device redundancy technology to achieve the simple deployment model. |
With VLT: RSTP | With vPC: MST | With RSTP and MST enabled, considering that MST uses the RSTP convergence timers, and the fact that only a single spanning tree instance is running between the two different regions, we should expect to get better convergence times. |