This bitmask indicates which protocols this port can support.
This object is mandatory for all ports in systems where the
nbsCmmcSysProtoTable is supported.
Bit 0 is reserved.
Subsequent bits refer to the nbsCmmcSysProtoTable. Bit 1
corresponds to the first table entry, Bit 2 to the second entry,
and so on. A bit is set (1) if that protocol is available for
this port, cleared (0) if unavailable.
Bit 1 always indicates 'custom' aka 'userDefined' is supported.
Bit 2 always indicates 'bypass' aka 'transparent' is supported.
OCTET STRING bitmasks count the leftmost bit (MSB) as 0.
A zero length OCTET STRING indicates that this object is not
supported.