This object specifies the IPCP IP subnet mask option for a
target PPP connection:
'other'
The implementation of this MIB module does not recognize
the configured IP subnet mask option.
'request'
The system requests the IP subnet mask from the peer of
a target PPP connection.
'reject'
The system rejects the IP subnet mask option from the
peer of a target PPP connection.
This column is valid only if the 'ipcpMaskOption' bit of the
corresponding instance of cdtPppValid is '1'.