Wan

SMDS, or Switched Multimegabit Data Service, has not yet gained significant market penetration, although it has begun to experience some growth. SMDS was viewed as a stepping stone to ATM, since some of the communications equipment and media are common to the two technologies. As SMDS is not available everywhere, and there is more interest in ATM, SMDS has had a hard time getting into the mainstream. SMDS does, however, have some penetration; if your long-distance carrier is MCI, you may have cause to use this technology. The attraction of SMDS is that it has the potential to provide high-speed, link-level connections (initially in the 1 to 34 Mbps range) with the economy of a shared public network, and exhibits many of the qualities of a LAN. ...

What is HDLC? HDLC stands for High-Level Data Link Control protocol. Like the two other WAN protocols mentioned in this article, HDLC is a Layer 2 protocol. HDLC is a simple protocol used to connect point to point serial devices. For example, you have point to point leased line connecting two locations, in two different cities. HDLC would be the protocol with the least amount of configuration required to connect these two locations. HDLC would be running over the WAN, between the two locations. Each router would be de-encapsulating HDLC and turning dropping it off on the LAN. ...