HDFC Securities's report says that the increase of 8% in the total open interest (OI) indicate that fresh positions have been built up.Also OI Put Call ratio declined marginally from 1.56 to 1.50. If Nifty crosses 3,600 levels it could move further up.Sensex will face resistances at 12546 and 12671 while strong supports will come in at 12310.