ZyXEL Communications MGS-3712/MES-3728 User Manual page 146

Chapter 13 Spanning Tree Protocol
Table 32 Advanced Application > Spanning Tree Protocol > Status: MSTP
LABEL
Internal Cost
Port ID
146
DESCRIPTION
This is the path cost from the root port in this MST instance to the
regional root switch.
This is the priority and number of the port on the Switch through which
this Switch must communicate with the root of the MST instance.
MES-3728 User's Guide