I was having a talk with a friend and told him about the following WAN protocols (PPP, HDLC, Frame-Relay).
He then said that RIP and OSPF could be used over WAN as well.
My understanding was that only WAN protocols could be used on a WAN (Frame-Relay, HDLC, PPP, ATM, etc.) and that RIP, OSPF, EIGRP, IGRP, BGP, etc. were all LAN protocols for connecting routers.
Is my understanding of the concepts screwed up or was my friend wrong?