For PS3 is not necesary open ports if you have enabled uPnP, some days ago I disabled UPNP and did port forwarding to PS3 because I heard a rumour this affects online, when I did this nobody entered to my room I created, I asked for help to a friend and he said me he cannot view my room in list.
UPNP (in PS3) is necesary for be "viewed" in player match list of available rooms.