  We focus on the confinement of two-dimensional Dirac fermions within the
waveguides created by realistic magnetic fields. Understanding of their band
structure is of our main concern. We provide easily applicable criteria, mostly
depending only on the asymptotic behavior of the magnetic field, that can
guarantee existence or absence of the energy bands and provide valuable insight
into the systems where analytical solution is impossible. The general results
are employed in specific systems where the waveguide is created by the magnetic
field of a set of electric wires or magnetized strips.
