  We discuss the general models with one time-like extra dimension and parallel
3-branes on the space-time $M^4 \times M^1$. We also construct the general
brane models or networks with $n$ space-like and $m$ time-like extra dimensions
and with constant bulk cosmological constant on the space-time $M^4\times
(M^1)^{n+m}$, and point out that there exist two kinds of models with zero bulk
cosmological constant: for static solutions, we have to introduce time-like and
space-like extra dimensions, and for non-static solutions, we can obtain the
models with only space-like extra dimension(s). In addition, we give two
simplest models explicitly, and comment on the 4-dimensional effective
cosmological constant.
