I have Cisco CatStack devices that re not having the serial number populated on the interfaces tab for modules why is this

Document ID : KB000105872
Last Modified Date : 10/07/2018
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Question:
I have Cisco CatStack devices that re not having the serial number populated on the interfaces tab for modules why is this
 
Answer:
For all CatStack device types we certify, we will update ‘DeviceSerialAttr’ with OID attr (chassisId) which points to Serial Number of stack device in MIB.  
Spectrum will read this ‘DeviceSerialAttr’ to pull the serial Number. deviceSerialAttr is always being read on the Master Stack- The modules are not checked individually.
 
If this attribute value not exists means Spectrum doesn’t know OID of serial number.
In this case, it reads ‘Entity Physical Serial Number’ to get Serial Number and updates  the same to all Interfaces/Modules.
In this scenario all the interfaces are updated by the device Serial Number.