Gently insert the LC, SC, or ST connector into the transceiver or optical port on both ends of the cable. Optical cables, also known as fiber optic cables, are becoming increasingly popular for their superior audio quality and data transmission capabilities. However, for those new to this technology, inserting an optical cable correctly can be a daunting task. In this step-by-step guide, we will walk. This tutorial provides an overview of SDH/SONET, covering basics, HDLC framing, terminologies, rates, and the SONET STS-1 SDH Frame. SONET (Synchronous Optical Network) and SDH (Synchronous Digital Hierarchy) serve the same purpose: communication over optical fiber links.