Terminology » Fiber Optic » SDH Hierarchy: STM Levels and Bit Rates Explained

SDH Hierarchy: STM Levels and Bit Rates Explained

sdh synchronous digital hierarchy bit rate stm optical communication

This article explains the Synchronous Digital Hierarchy (SDH) and its different levels, including STM-0, STM-1, STM-4, STM-16, STM-64, and STM-256, focusing on their bit rates and their relationship with E1 and E4 carrier systems.

SDH Terminology and Bit Rates

The following table outlines the various SDH terms, their corresponding bit rates, abbreviated bit rates, and SDH capacity in terms of E1 and E4 channels.

SDH TerminologyBit rateAbbreviated bit rateSDH capacity
STM-051.84 Mbits/sec51 Mbps21 E1
STM-1155.52 Mbits/sec155 Mbps63 E1 or 1 E4
STM-4622.08 Mbits/sec622 Mbps252 E1 or 4 E4
STM-162488.32 Mbits/sec2.4 Gbps1008 E1 or 16 E4
STM-649953.28 Mbits/sec10 Gbps4032 E1 or 64 E4
STM-25639813.12 Mbits/sec40 Gbps16128 E1 or 256 E4