I First found in version
II The version(s) already found this problem
III Description of the problem
As shown above, Bridge A, B, C and D belongs to the same MST Region, while A is the Root Bridge of CIST and MSTI N (N≠0), the role of Port 6 is Alternate in CIST and MSTI N. To set B as the Root Bridge of MSTI N and then set A as the Root Bridge of MSTI N once again.STP converges again, the role of Port 4 is designated in MSTI N, but it won’t be transitioned to Forwarding Port State from discarding rapidly.
Update to version S3600EI-CMW310-R1510P21.