To enable the MSTI, use the following command and specify the MSTI domain as the stpd_name:
enable stpd {stpd_name}
Note
If two switches are configured for the same CIST and MSTI region, in order for them to understand that they are in the same region, both must also belong to the same VLAN which is added to the STP domain. If they belong to different VLANs, each switch believes that each belongs to a different region. When an MSTP BPDU is sent, it carries a VID digest created by VLAN memberships in the CIST domain and the MSTI domain.