MSTP with VSX guidelines
Path cost is not allowed to be configured on the ISL port.
VSX must be root for MSTP.
Layer 2 link connected parallel to ISL link is blocked by MSTP.
Do not configure port-specific spanning tree configurations on the ISL.
Multiple MSTP regions are not supported. Multiple instances are supported though (default + 64).
Topology changes for VSX LAGs are accounted on the active multichassis LAG role only.
MSTP is supported in both VSX and non-VSX environments.
The common bridge ID continues to be used even after the VSX split brain scenario is identified.
Interoperability with RSTP is not supported with a direct connection to the VSX environment. For example, interoperability between MST Instance 0 (CST) to RSTP is not supported. The VSX pair is configured as a nonroot switch.
STP configurations on VSX LAG ports must be the same on VSX switches.
- Run the
show running-config spanning tree
andshow running-config spanning tree vsx-peer
commands for verifying that the following global parameters are the same on VSX switches:STP mode.
STP region configuration for MSTP (config-name and config-revision)
STP instance to VLAN mapping
STP instance priority