Submitting a form into an iframe in another page

I have a web page called index1.aspx that contains an iFrame called main_iframe. In another page called index2.aspx I have an iFrame called iframe2

Now, my problem is that I'm trying to submit a form in index2.aspx > iframe2 and the results target to be the main_iframe on in开发者_如何学运维dex1.aspx