@classmethod
def get(cls, top, parent=None):
    """
        This will get all of the switch bd on the
        specified node.  If no node is specified, then
        it will get all of the bds on all
        of the switches.

        :param parent:
       :param top: the topSystem level json object
       :returns: list of Switch bridge domain
        """
    cls.check_parent(parent)
    result = []
    bd_data = top.get_class('l2BD')
    for l2bd in bd_data:
        bdomain = cls()
        bdomain._top = top
        bdomain._populate_from_attributes(l2bd['l2BD']['attributes'])
        bdomain._get_cxt_name(top)
        bdomain._get_multicast_flood_address(top)
        result.append(bdomain)
        if parent:
            bdomain._parent = parent
            bdomain._parent.add_child(bdomain)
    return result
