An StpdID is used to identify each STP domain.
When assigning the StpdID when configuring the domain, ensure that the carrier VLAN of that STPD does not belong to another STPD. Unless all ports are running in 802.1D mode, an STPD with ports running in either EMISTP mode or PVST+ mode must be configured with an StpdID.
An StpdID must be identical to the VLAN ID of the carrier VLAN in that STP domain. For an 802.1D STPD, the VLAN ID can be either a user-defined ID or one automatically assigned by the switch.
NoteIf an STPD contains at least one port not in 802.1D mode, you must configure the STPD with an StpdID.
MSTP uses two different methods to identify the STPDs that are part of the MSTP network. An instance ID of 0 identifies the CIST. The switch assigns this ID automatically when you configure the CIST STPD. An MSTI identifier (MSTI ID) identifies each STP domain that is part of an MSTP region. You assign the MSTI ID when configuring the STPD that participates in the MSTP region. In an MSTP region, MSTI IDs only have local significance. You can reuse MSTI IDs across MSTP regions. For more information about MSTP and MSTP features, see Multiple Spanning Tree Protocol.