Configuring the CIST
Configure an STPD as the CIST, specifying the mstp cist keywords in the following command:
configure stpd stpd_name mode [dot1d | dot1w | mstp [cist | msti instance]]
You can enable MSTP on a per STPD basis only. By specifying the mstp cist keywords, you can configure the mode of operation for the STPD as MSTP and identify the STPD to be the CIST.