Hi

This is probably quite a broad topic/question -- but I was wondering how does ADSL services work from an ISP perspective.
For Example how does it work that an ISP gives you a Username and Password, you pop it into your ADSL modems PPPoE and it connects giving you internet access - unlike with RAS/PPP services where you dial a number to get connectivity logging in from there.

Question 1: How does your modem router know to connect with your ISP based on your username in format NAME@ISPDOMAIN -- how does it get the Domain connectivity information?

Question 2: If for example (just wondering in a theoretical sense) you wanted to host an ADSL service how would you go about it and what would be needed other than Internet routable IPs and a big wad of Bandwidth?

Purely wondering out of interest