An OLT (Optical Line Terminal) is the core device in a Passive Optical Network (PON) — the interface between the core network and the subscriber's optical access network. It aggregates multiple ONUs/ONTs through optical splitters and handles data distribution, management, and. In modern communication networks, optical line terminal (OLT) is the core device to realize point-to-multipoint (P2MP) in passive optical network (PON) architecture. In this guide, we'll demystify what an.