If VC:MP PC is "directly" connected to internet , it needs a modem/router to connect to internet, right? Whats the difference? Both are same?!
Modem and
router are two different things. Modem (
modulator-
demodulator) is used to encode transmited and decode received data. Router, on the other hand, is technically a computer. It can act as a
switch,
firewall or even act as a server machine with an external IP (like on the scheme I've shown).
So, it depends on how does your "modem/router" act. If it's just a modem, then it passes data directly to one of your PC's
adapters with an external IP and you don't need any forwarding.
If your ADSL modem is also a router, then it is likely that it has an external IP which your computer uses through a local IP. In this case your computer can only be accessed from the internet if ports are forwarded on your router.
If you didn't forward anything and people are able to connect, then you don't have a router at all, just a modem.