If the value of 'jnxMplsFecType' is 'prefix(1)'
then the value of this object is the length in
bits of the address prefix represented by
'jnxMplsFecAddr', or if the length is zero then
this is a special value which indicates that the
prefix matches all addresses. In this case the
prefix is also zero (i.e. 'jnxMplsFecAddr' will
have the value of zero.)