said by MrMazda86:There is no "virtual link". Understand that PPP operates at the data link layer and doesn't care about IP at all; it's just a way of encapsulating data to relay it from one node to another across a network. The "inner workings" are the same whether you have a static or dynamic IP; it's still a PPP link using IPCP to configure the relay of frames containing IP packets over the link.
Also, Subnets are a completely different breed because they're a "virtual" link for lack of a better term. Even when running a subnet, you still have that one static IP for the PPPoE link. When you're not bound to a static IP on the other hand, the inner workings of it are different.