  We propose a Landauer-like theory for nonlinear transport in networks of
one-dimensional interacting quantum wires (Luttinger liquids). A concrete
example of current experimental focus is given by carbon nanotube Y junctions.
Our theory has three basic ingredients that allow to explicitly solve this
transport problem: (i) radiative boundary conditions to describe the coupling
to external leads, (ii) the Kirchhoff node rule describing charge conservation,
and (iii) density matching conditions at every node.
