scope:

This Supplement describes existing methods and a synchronous digital hierarchy (SDH) based method to support the transport of sub-1G signals through the optical transport network (OTN). A sub-1G signal is a digital signal whose bit rate is included in a range from nominally 2 Mbit/s to less than nominally 1 Gbit/s. Sub-1G signals include, for example, E1 and E3 signals according to [ITU-T G.703], VC-12, VC-3 and VC-4 signals according to [ITU-T G.707], STM-1 or STM-4 signals according to [ITU-T G.707] and fast Ethernet 100BASE-TX/FX according to clause 21 of [IEEE 802.3].

Existing methods include, for example, mapping the sub-1G service signal into ODU0 as specified in [ITU-T G.709], mapping the sub-1G service signal into SDH VC-n that are aggregated to STM-N and mapped into ODUk and circuit emulation of the sub-1G service signal and mapping into Ethernet virtual local area network (VLAN) or multiprotocol label switching-transport profile (MPLS-TP) pseudowire (PW) with optional packet aggregation and mapping into ODUk/flex. The SDH-based method is intended to describe OTN frame structures that channelize the payload of an existing ODU0, providing a method of aggregating sub-1G service signals in a bandwidth-efficient manner, and support monitoring and protection of sub-1G services.