STM-1 (Optical / Electrical), E1 and Ethernet Multi-Service SDH Transmission Unit is a modular platform unit with two 155. 52Mbps optical / electrical interfaces, which may be used in a point-to-point, chain or ring application to provide an ultra-compact, cost effective and flexible. The module (see Figure 16-1) contains eight optical STM-1 interfaces that meets the S-1. The physical connector is a LC connector. Higher levels go up by a factor of 4 at a time: the other currently supported levels are STM-4, STM-16, STM-64 and STM-256.
