1.about Linux Bridge

several years ago ,when I started delving into Linux kernel networking subsystem for the first time,Linux Bridge was my second one of the projects which came into my mind .at the time I was focusing on how to generate a kernel network device when I issue a command #brctl addbr br-test in userspace,and no attention to other details at all.now I am back again ,and this time ,I will tell more specific about it as my summary.