Dell SmartFabric OS10 User Guide Release 10.5.4

RSTP/MSTP/Rapid-PVST is compatible and interoperable with the Spanning Tree Algorithm and Protocol (STP). An administrative Force Protocol Version parameter allows you to emulate the behavior of the previous versions of the spanning tree protocol that are not required for interoperability. The parameter applies to all the Bridge Ports.

Force protocol version in RSTP

Spanning-tree RSTP force-version (STP)

• Setting the force version to STP forces the RSTP protocol to operate in 802.1D STP mode instead of the default protocol mode, RSTP.
• If the force version is STP, the rapid transitions are disabled.
• Default behavior is RSTP operation mode, which supports faster convergence.

Force protocol version in MSTP

Spanning-tree MST force-version (STP/RSTP)

• Setting the force version to STP forces the MSTP protocol to operate in 802.1D STP mode instead of the default protocol mode, MSTP.
• If Force Protocol Version is STP, rapid transitions are disabled.
• Setting the force version to RSTP forces the MSTP protocol to operate in 802.1w RSTP mode instead of the default protocol mode, MSTP. In this mode, it transmits RST BPDU which skips the MSTI information.
• If Force Protocol Version is STP or RSTP, the received BPDUs are considered from a different MST Region.
• Default behavior is MSTP operation mode, which allows full MSTP behavior.
• OS10 does not support enabling force version per MST instance.

Force protocol version in Rapid-PVST

Spanning-tree Rapid-PVST force-version (STP)

• Setting the force version to STP forces the Rapid-PVST protocol to operate in 802.1D STP mode instead of the default protocol mode RSTP on VLAN 1.
• If force version is STP, the rapid transitions are disabled on VLAN 1.
• OS10 does not support running force version STP on per VLAN level.