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optical data unit (SDH) (ODU)

The Optical Data Unit (ODU) is an ultra-wideband signal format for monitoring a wideband optical channel in SDH networks. The Optical Data Unit contains the Optical Payload Unit( OPU) in which the user data of the various networks are contained and also supports the sectional error control, the Tandem Connection Monitoring( TCM).

This format, in which client signals are mapped with their bit rates and formats, provides optimized support at nominal bit rates of 2.5 Gbit/s (ODU-1), 10 Gbit/s (ODU-2) and 40 Gbit/s (ODU-3); making more bandwidth available to the data communications network. In addition to these nominal bit rates, another level in the OTH hierarchy was defined in 2007 with 120 Gbit/s, ODU-4.

OTU types and their transmission rates

OTU types and their transmission rates

The ODU-4 super containers support the fully transparent transport of nine 10 Gigabit Ethernet or also 100 Gigabit Ethernet. In both cases, the ODU-4 container offers sufficient space to transport all payloads with their overheads. Optical Data Units can be converted into OPU-2 and OPU-3 Optical Payload Units relatively easily by mapping.

OTN structure of the data units

OTN structure of the data units

Due to the increasing use of Ethernet in optical transport networks and the limited support of broadband Ethernet by G.709, additional transport containers have been defined: ODU-0 and ODUflex. Since an ODU-1 container with a payload capacity of 2.488 Gbit/s serving a Gigabit Ethernet client gives away a considerable amount of bandwidth, G.709 has developed ODU-0, a container with half the transmission rate of ODU-1, namely for 1.244 Gbit/s. This container is designed to be used for the transmission of data from a Gigabit Ethernet client.

Informations:
Englisch: optical data unit (SDH) - ODU
Updated at: 29.11.2011
#Words: 258
Links: signal, monitoring, optical channel (OCh), synchronous digital hierarchy (SDH), optical payload unit (OTN) (OPU)
Translations: DE
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