Optimize and enhance the code of "test_routers.py"

Most of test cases under "test_routers.py" are not using base network
class method but instead of that creating their own methods.
So this patch will enhance the code and will use the base network class
methods.

Change-Id: I65b17d1b421a8095e89d7acd27d07835903c5d87
1 file changed