WAN Protocol Family
A variety of different protocols are used on "wide-area networks" or WANs. At the physical layer, a line carrying a T1/E1/J1 signal or higher-speed T-carrier or E-carrier lines, or a fraction thereof, or a SONET/SDH optical link, or fraction thereof, could be used. Alternatively, a connection to a switched network, such as an X.25, FrameRelay, or ATM network might be used, with a line or optical connection such as the ones listed being used for that connection.
10-gigabit Ethernet was intended to be used not only as a LAN or MAN protocol, but also as a WAN protocol.
XXX - add a brief description of the history of the protocol family
PPP: The Point-to-Point protocol
Cisco HDLC: Cisco's proprietary (but public) encapsulation protocol
- add links to pages and sites with information about that protocol family, such as an organization responsible for defining and maintaining the protocol family