[Serusers] avpops and ip based auth

[Iqbal]

Hi

If I use avpops for IP based auth, and drop the normal username/password 
combo aside from spoofing what is the downside if any. Also if I do IP 
based auth, can I auth once, and be done with it, or is it auth once per 
call, I guess its once per call, if so is there any way to bypass auth 
completely for a particular IP address, again I am assuming no, since 
the IP will still need to be checked for each request.

Iqbal