redirect once

redirect only if its not the iframe

[fedefinki]

Hi,
I have site A that has an iframe pointing to site B.
The thing is that i want to redirect all visitors that access site B to site A, but when they get redirected to site A i don't want that the iframe containing site B redirects again to site A.
i dont know if i make my self clear, my problem is that because i have placed a 301 redirect from site B to site A, when i go to site A i see site A again in the iframe instead of only site B, i think i am geting into a redirect loop.

I don't know if this matters but both sites are hosted in the same server and B is subdomain of A.
sorry if i shaked your heads with AB BA AB thing.
thanks.

[g1smd]

Use a RewriteCond looking at the requested URL and set it so that it does NOT redirect for the URL of the content shown inside the iframe.

[fedefinki]

Any suggestions on how to do that?
thanks.