Column('machine_id', Integer, ForeignKey('machines.machine_id'), nullable=True),
Column('mac_addr', String, nullable=False, primary_key=True),
Column('ip', String, nullable=False, unique=True),
Column('machine_id', Integer, ForeignKey('machines.machine_id'), nullable=True),
Column('mac_addr', String, nullable=False, primary_key=True),
Column('ip', String, nullable=False, unique=True),