When I google "whats my IP" it says, something like "112.134.x.y". But when I go to the router configurations and under WAN IP it says "100.68.a.b"(As far as I know it's a routable IP). So, I must be behind a Carrier Grade NAT (CGN).
But torrent clients i.e uTorrent and BitTorrent can do Uploading or Downloading without any problem. How they do that?.
My home router's UPnP ability is turned off and when I try to figure out whats happening behind curtains using Wire Shark, I can see NAT-PMP requests for port mapping from uTorrent (192.168.1.100 : 5351) to my home router (192.168.1.1 : 5351) and for external IP discovery. But I cant see any responses back to port 5351 !. (What does that mean?)
FYI I'm a student who "trying" to make a P2P networking system like BitTorrent to work behind NATs. So any documentation on this topic would be great.....(I know about methods i.e Hole Punching, NAT-PMP, PCP, UPnP)