Hi I cannot understand concept basics on WAN Technology. Please help

What does it mean when people say they are running frame-relay or HDLC or DS-3, OC-3 etc. Frame-relay is not a physical access it operates on layer 2 so why does some people say they are running frame-relay when in fact its L2. On physical layer it can run over copper or fiber etc. Same for the others DS-3/OC-3 is not physical layer. the physical is copper, fiber

With regards to new technology like MPLS it uses Frame-relay encap to provide connection as far as i know than how can MPLS replace Frame-Relay or DS-3 or Sonet etc.

Is Sonet, DWDM etc also encapsulation protocols.

Today mostly ethernet is also starting to be used for WAN access so would the term mpls over ethernet be right. mpls and ethernet operate at layer 2 than how can one be carried over the other

At times MPLS can be used to carry ethernet hence term EoMPLS but MPLS is only encapsulation protocol. the underlying physical layer must be a connection like OC-3 or Gigabit Ethernet over Fiber/Copper

Tx