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ITU-T G.812 (06/2004)

Требования к хронированию ведомых тактовых генераторов, пригодных для использования в качестве узловых тактовых генераторов в сетях синхронизации

В данной Рекомендации описываются минимальные требования к устройствам синхронизации, используемым в качестве узловых тактовых генераторов в сетях синхронизации. Эти требования касаются характеристик отклонения частоты; полосы захвата, удержания и потери частоты; генерации, допуска и переноса шума; характеристик переходного и несинхронизированного режимов. Тактовые генераторы узла подходят для использования в сетевых приложениях КТСОП и СЦИ. Настоящая Рекомендация включает спецификации для трех типов тактовых генераторов. Тип I прежде всего предназначен для использования в сетях, оптимизированных для иерархии 2048 кбит/с. Типы II и III прежде всего предназначены для использования в сетях, оптимизированных для определенной иерархии 1544 кбит/с, которая включает скорости 1544 кбит/с, 6312 кбит/с и 44 736 кбит/с. Дополнительно эта Рекомендация включает в Приложении A спецификации для трех других тактовых генераторов. Тип IV обычно применяется в существующих сетях, которые поддерживают скорость 1544 кбит/с. Тактовые генераторы типов V и VI были определены для приложений транзитных и локальных узлов в версии 1988 года этой Рекомендации.

Citation:	https://handle.itu.int/11.1002/1000/7335
Series title:	G series: Transmission systems and media, digital systems and networks G.800-G.899: Digital networks G.810-G.819: Design objectives for digital networks
Approval date:	2004-06-13
Approval process:	AAP
Status:	In force
Observation:	The typo corrected by G.812 (2004) Erratum 1 is included in the electronic version of this Recommendation
Maintenance responsibility:	ITU-T Study Group 15
Further details:	Patent statement(s) Development history

Ed.	ITU-T Recommendation	Status	Summary	Table of Contents	Download
6	G.812 (06/2004)	In force	here	here	here
6.0	G.812 (2004) Err. 1 (03/2005)	In force	-	-	here
5	G.812 (06/1998)	Superseded	here	here	here
4	G.812 (11/1988)	Superseded	-	here	here


ITU-T Supplement	Title	Status	Summary	Table of contents	Download
G Suppl. 4 (12/1972)	Certain methods of avoiding the transmission of excessive noise between interconnected systems	In force	-	-	here
G Suppl. 5 (10/1984)	Measurement of the load of telephone circuits under field conditions	In force	-	-	here
G Suppl. 7 (12/1972)	Loss-frequency response of channel-translating equipment used in some countries for international circuits	In force	here	here	here
G Suppl. 8 (12/1972)	Method proposed by the Belgian telephone administration for interconnection between coaxial and symmetric pair systems	In force	-	-	here
G Suppl. 17 (10/1984)	Group-delay distortion performance of terminal equipment	In force	-	-	here
G Suppl. 19 (10/1984)	Digital crosstalk measurement (method used by the Administrations of France, the Netherlands and Spain)	In force	-	-	here
G Suppl. 22 (10/1984)	Mathematical models of multiplex signals	In force	-	-	here
G Suppl. 26 (10/1984)	Estimating the signal load margin of FDM wideband amplifier equipment and transmission systems	In force	-	-	here
G Suppl. 27 (10/1984)	Interference from external sources	In force	-	-	here
G Suppl. 28 (10/1984)	Application of transmultiplexers, FDM codecs, data-in-voice (DIV) systems and data-over-voice (DOV) systems during the transition from an analogue to a digital network	In force	-	-	here
G Suppl. 32 (11/1988)	Transfer of alarm information on 60-channel transmultiplexing equipment	In force	-	-	here
G Suppl. 34 (11/1988)	Temperature in underground containers for the installation of repeaters	In force	-	-	here
G Suppl. 35 (11/1988)	Guidelines concerning the measurement of wander	In force	-	-	here
G Suppl. 36 (11/1988)	Jitter and wander accumulation in digital networks	In force	-	-	here
G Suppl. 39 (03/2025)	Optical system design and engineering considerations	In force	here	here	here
G Suppl. 40 (07/2024)	Optical fibre and cable Recommendations and standards guideline	In force	here	here	here
G Suppl. 41 (07/2024)	Design guidelines for optical fibre submarine cable systems	In force	here	here	here
G Suppl. 42 (10/2018)	Guide on the use of the ITU-T Recommendations related to optical fibres and systems technology	In force	here	here	here
G Suppl. 43 (02/2011)	Transport of IEEE 10GBASE-R in optical transport networks (OTN)	In force	here	here	here
G Suppl. 44 (06/2007)	Test plan to verify B-PON interoperability	In force	here	here	here
G Suppl. 45 (09/2022)	Power conservation in optical access systems	In force	here	here	here
G Suppl. 46 (05/2009)	G-PON interoperability test plan between optical line terminations and optical network units	In force	here	here	here
G Suppl. 47 (03/2025)	General aspects of optical fibres and cables	In force	here	here	here
G Suppl. 48 (06/2010)	10-Gigabit-capable passive optical networks: Interface between media access control with serializer/deserializer and physical medium dependent sublayers	In force	here	here	here
G Suppl. 49 (09/2020)	Rogue optical network unit (ONU) considerations	In force	here	here	here
G Suppl. 50 (09/2011)	Overview of digital subscriber line Recommendations	In force	here	here	here
G Suppl. 51 (06/2017)	Passive optical network protection considerations	In force	here	here	here
G Suppl. 52 (09/2012)	Ethernet ring protection switching	In force	here	here	here
G Suppl. 53 (12/2014)	Guidance for Ethernet OAM performance monitoring	In force	here	here	here
G Suppl. 54 (07/2015)	Ethernet linear protection switching	In force	here	here	here
G Suppl. 55 (12/2023)	Radio-over-fibre (RoF) technologies and their applications	In force	here	here	here
G Suppl. 56 (02/2016)	OTN transport of CPRI signals	In force	here	here	here
G Suppl. 57 (07/2015)	Smart home profiles for 6LoWPAN devices	In force	here	here	here
G Suppl. 58 (07/2024)	Optical transport network module framer interfaces	In force	here	here	here
G Suppl. 59 (02/2018)	Guidance on optical fibre and cable reliability	In force	here	here	here
G Suppl. 60 (09/2016)	Ethernet linear protection switching with dual node interconnection	In force	here	here	here
G Suppl. 62 (02/2018)	Gfast certification	In force	here	here	here
G Suppl. 64 (02/2018)	PON transmission technologies above 10 Gb/s per wavelength	In force	here	here	here
G Suppl. 65 (10/2018)	Simulations of transport of time over packet networks	In force	here	here	here
G Suppl. 66 (09/2020)	5G wireless fronthaul requirements in a passive optical network context	In force	here	here	here
G Suppl. 67 (07/2019)	Application of optical transport network Recommendations to 5G transport	In force	here	here	here
G Suppl. 68 (12/2023)	Synchronization operations, administration and maintenance requirements	In force	here	here	here
G Suppl. 69 (09/2020)	Migration of a pre-standard network to a metro transport network	In force	here	here	here
G Suppl. 70 (09/2020)	Supplement on sub 1 Gbit/s services transport over optical transport network	In force	here	here	here
G Suppl. 71 (12/2023)	Optical line termination capabilities for supporting cooperative dynamic bandwidth assignment	In force	here	here	here
G Suppl. 72 (03/2025)	Modelling consideration for optical media networks	In force	here	here	here
G Suppl. 73 (10/2021)	Influencing factors on quality of experience for multiview video (MVV) services	In force	here	here	here
G Suppl. 74 (12/2021)	Network slicing in a passive optical network context	In force	here	here	here
G Suppl. 75 (12/2021)	5G small cell backhaul/midhaul over TDM-PON	In force	here	here	here
G Suppl. 76 (12/2021)	Optical transport network security	In force	here	here	here
G Suppl. 77 (06/2022)	Supplement 77 to ITU-T G-series of Recommendations - Influencing factors on quality of experience (QoE) for video customized alerting tone (CAT) and video customized ringing signal (CRS) services	In force	here	here	here
G Suppl. 78 (09/2022)	Use case and requirements of fibre-to-the-room for small business applications	In force	here	here	here
G Suppl. 79 (12/2023)	Latency control and deterministic capability over a PON system	In force	here	here	here
G Suppl. 80 (07/2024)	Use case and requirements of fibre-based in-premises networking for home application (FIP4H)	In force	here	here	here
G Suppl. 81 (07/2024)	Practical aspects of PON security	In force	here	here	here
G Suppl. 82 (07/2024)	Enhanced optical line termination with information technology functions	In force	here	here	here
G Suppl. 83 (07/2024)	Supplement on the use of options in the precision time protocol profile with full timing support from the network	In force	here	here	here
G Suppl. 84 (03/2025)	Operational aspects of optical access	In force	here	here	here
G Suppl. 85 (03/2025)	FgODU over point-to-multipoint networks	In force	here	-	here
G Suppl. 86 (03/2025)	Fibre to the power grid (FTTGrid) use cases and network requirements	In force	here	here	here
G Suppl. 87 (03/2025)	Standardization framework for optical fibres for space division multiplexing	In force	here	here	here

Title	Approved on	Download
Roadmap for QoS and QoE in the ITU-T Study Group 12 context (TR-RQ)	2023	here
Considerations on the use of GNSS as a primary time reference in telecommunications	2020	here
Use of G.hn in industrial applications	2020	here
ISDN field trial guidelines	1991	here

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ITU-T Recommendations

ITU-T G.812 (06/2004)