when the switch powers on, it automatically begins the power-on self test (post), a series of tests that verifies that the switch functions properly. when the switch begins post, the system led slowly blinks green. when post completes, the system led blinks amber. if post fails, the system led remains amber. if post completes successfully, the system led rapidly blinks green.

    post failures are usually fatal. call cisco systems if your switch does not pass post.