Page 1090 - 5G Basics - Core Network Aspects

2 Transport aspects

Summary

Recommendation ITU-T G.709/Y.1331 defines the requirements for the optical transport network (OTN)
interface signals of the optical transport network, in terms of:
– OTN hierarchy
– functionality of the overhead in support of multi-wavelength optical networks
– frame structures
– bit rates
– formats for mapping client signals.

Edition 5.0 of this Recommendation includes the text of Amendments 2, 3, 4, Corrigendum 2 and Erratum 1
to Edition 4.0 of this Recommendation, support for frequency and time synchronisation, addition of Beyond
100 Gbit/s OTU, ODU and OPU frame formats, overhead, ODU multiplexing, client mappings and optical
layer terminology updates. Edition 5.0 furthermore deleted the OPUk concatenation specifications and the
ATM mapping into OPUk specification and changed the TCM ACT and FTFL overhead bytes into EXP
overhead bytes.
This amendment contains extensions to the fifth edition (06/2016) of Recommendation ITU-T
G.709/Y.1331, related to the:
– Addition of paragraph that describes that ITU-T G.798 complements ITU-T G.709 (1)
– Addition of references to Recommendation ITU-T G.8260 (2)

– Addition of definitions and conventions that have been included in the past in ITU-T G.870 (3, 5)
– Deletion and addition of abbreviations (4)
– Addition of a sentence that describes that 3R regeneration is used on both sides of an interface
interconnecting user and provider administrations and two provider administrations (6)
– Corrections to the STU, MOTU, SOTUm and MOTUm descriptions (8.1, 8.2, 8.3, 8.4)
– Addition of a note describing a vendor specific mode in the GCC0 communication channel
deployment (15.7.2.2)
– Deletion of OTUCn OSMC (15, 15.7.1, 15.7.2.4, 15.7.2.4.1.2)
– Deletion of reference to concatenation (15.9.2)
– Aligning the OPUk/OPUflex clock performance requirement in case of BMP based client mapping
with ITU-T G.8251 and ITU-T G.798 (17.2, 17.19, 17.12)
– Clarify the 2-bit alignment when mapping 66-bit blocks into the OPUflex payload area (17.11,
17.12)
– Changing the minimum number of FlexE signals in a FlexE aware mapping into an OPUflex (17.12)
– Addition of 25GE client signal (2, 15.9.2.1.1, 17.13, 17.13.1)

– Deletion of ODUCn HAO reference (20.4.3.1).

Keywords
Client mappings, frame formats, multiplexing, OTN.

1080