Spanning-Tree Operation 
802.1s Multiple Spanning Tree Protocol (MSTP) 
Displaying the Region-Level Configuration in Brief.  This command 
output is useful for quickly verifying the allocation of VLANs in the switch’s 
MSTP configuration and for viewing the configured region identifiers. 
Syntax:  show spanning-tree mst-config 
This command displays the switch’s regional configuration. 
Note: The switch computes the MSTP Configuration Digest  from 
the VID to MSTI configuration mappings on the switch itself. 
As required by the 802.1s standard, all MSTP switches  within 
the same region must have the same VID to MSTI assignments, 
and any given VID can be assigned to either the IST or one of 
the MSTIs within the region. Thus, the MSTP Configuration 
Digest must be identical for all MSTP switches intended to 
belong to the same region. When comparing two MSTP 
switches, if their Digest identifiers do not match, then they 
cannot be members of the same region. 
Refer to the “Note”, above. 
Figure 5-32.  Example of a Region-Level Configuration Display 
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