Source: https://www.scribd.com/document/217067369/Synchronization-Network-Architecture-Based-on-SDH
Timestamp: 2019-01-22 15:51:10
Document Index: 441812680

Matched Legal Cases: ['art 2', 'art 5', 'art 1', 'art 6', 'art 2', 'art 6', 'art 3', 'art 4', 'art 4', 'art 7', 'art 2', 'art 2', 'art 4', 'art 6', 'art 6', 'art 3', 'art 1', 'art 7', 'art 5']

Synchronization Network Architecture Based on SDH | Public Switched Telephone Network | Computer Networking
ETSI EN 300 462-2-1 V1.2.
Transmission and Multiplexing (TM); Generic requirements for synchronization networks; Part 2-1: Synchronization network architecture based on SDH networks
FRANCE Tel.org/tb/status/status. Information on the current status of this and other ETSI documents is available at http://portal. The copyright and the foregoing restriction extend to reproduction in all media. TM TIPHON and the TIPHON logo are Trade Marks currently being registered by ETSI for the benefit of its Members.org The present document may be made available in more than one electronic version or in print. Users of the present document should be aware that the document may be subject to revision or change of status.NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88 Important notice Individual copies of the present document can be downloaded from: http://www. the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat. synchronization. the reference version is the Portable Document Format (PDF). All rights reserved. © European Telecommunications Standards Institute 2002.2. SDH. In case of dispute.fr Copyright Notification No part may be reproduced except as authorized by written permission. DECT . PLUGTESTS and UMTS are Trade Marks of ETSI registered for the benefit of its Members.asp If you find errors in the present document. transmission ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex . In any case of existing or perceived difference in contents between such versions.1 (2002-06) Reference REN/TM-01092 Keywords architecture. send your comment to: editor@etsi.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N° 348 623 562 00017 .etsi.etsi. TM TM TM ETSI . TM 3GPP is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners.2 ETSI EN 300 462-2-1 V1.
..........................................................................................................................9 6 7 8 9 9............................................4 Synchronization network robustness..............................2 Synchronization network architecture.........................................2..............................................................................................................................................................................................................................................................................................................10 Synchronization modes .12 Synchronization network evolution...............................................15 Management ................................................................................................................................................7 Abbreviations ...........................................................................................................................................................2 Scope ......................................8 Synchronization Supply Unit (SSU) ............................................................................................14 SDH networks ................................3 10.........................11 Synchronization network reference chain .................14 10 10.......................................................................6 Definitions and abbreviations..............................................................................4 Foreword....................................................................................................................................................................1 3............................6 References ..................................................................................................................................................14 Synchronization status message ..................15 Annex A (informative): Bibliography........4 1 2 3 3.......................................................................................................................................7 Functional description of clock types.....................................................................................................................................7 Definitions..............................................................................................................................................1 10................................................................................................14 Optical Transport Networks ..................................................................8 SDH Equipment Clock (SEC) .........................................................................................................................................................17 ETSI .....................................................................................................................................7 4 5 5..............................1 9..........................................3 ETSI EN 300 462-2-1 V1..................................................16 History ...................................8 Primary Reference Clock (PRC) .........................................2 5..............................................................................................................1 5.............................14 General ......................................................................................................................................3 Synchronization methods ........2 10.............................................................................14 Trail redundancy ...................................................................................................................................................1 (2002-06) Contents Intellectual Property Rights ................................................
4 ETSI EN 300 462-2-1 V1. is publicly available for ETSI members and non-members. Foreword This European Standard (Telecommunications series) has been produced by ETSI Technical Committee Transmission and Multiplexing (TM). Latest updates are available on the ETSI Web server (http://webapp. Part 5-1: "Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hierarchy (SDH) equipment". no investigation. and can be found in ETSI SR 000 314: "Intellectual Property Rights (IPRs). Essential. or may become. as identified below: Part 1-1: "Definitions and terminology for synchronization networks". No guarantee can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server) which are. Part 6-1: "Timing characteristics of primary reference clocks".asp). which is available from the ETSI Secretariat. ETSI . Part 2-1: "Synchronization network architecture based on SDH networks".2. The present document has been produced to provide requirements for synchronization networks that are compatible with the performance requirements of digital networks.etsi. IPRs notified to ETSI in respect of ETSI standards". essential to the present document. or potentially Essential. Part 6-2: "Timing characteristics of primary reference clocks. Implementation Conformance Statement (ICS) proforma specification". Implementation Conformance Statement (ICS) proforma specification". Part 3-1: "The control of jitter and wander within synchronization networks". or may be. if any. Part 4-2: "Timing characteristics of slave clocks suitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment. Part 4-1: "Timing characteristics of slave clocks suitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment". Part 7-1: "Timing characteristics of slave clocks suitable for synchronization supply to equipment in local node applications".1 (2002-06) Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs. including IPR searches. Pursuant to the ETSI IPR Policy. has been carried out by ETSI. Part 2-1 has been revised in several sections with regard to the work done in EG 201 793 [7] and to reflect the present status of synchronization networks.org/IPR/home. The present document is part 2-1 of a multi-part deliverable covering generic requirements for synchronization networks. It is one of a family of documents covering various aspects of synchronization networks.
2.1 (2002-06) National transposition dates Date of adoption of this EN: Date of latest announcement of this EN (doa): Date of latest publication of new National Standard or endorsement of this EN (dop/e): Date of withdrawal of any conflicting National Standard (dow): 31 May 2002 31 August 2002 28 February 2003 28 February 2003 ETSI .5 ETSI EN 300 462-2-1 V1.
Generic requirements for synchronization networks. 2 References • References are either specific (identified by date of publication and/or edition number or version number) or non-specific. Generic requirements for synchronization networks. Generic requirements for synchronization networks. Generic requirements of transport functionality of equipment. ETSI EN 300 462-3-1: "Transmission and Multiplexing (TM). constitute provisions of the present document. Multiplexing structure". The following documents contain provisions which. Generic requirements for synchronization networks.6 ETSI EN 300 462-2-1 V1. It supports the construction of synchronization networks that support both the short-term stability requirements of SDH networks and the long-term stability requirements of digital switching networks (e. Part 4-1: Timing characteristics of slave clocks suitable for synchronization supply to Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) equipment". ETSI EG 201 793: "Transmission and Multiplexing (TM). ETSI EN 300 147: "Transmission and Multiplexing (TM). Part 6-1: Timing characteristics of primary reference clocks". ETSI EN 300 417-6-1: "Transmission and Multiplexing (TM). Part 6-1: Synchronization layer functions". ETSI EN 300 462-7-1: "Transmission and Multiplexing (TM). PSTN) connected to the SDH network. [1] [2] ETSI EN 300 462-1-1: "Transmission and Multiplexing (TM). ETSI EN 300 462-4-1: "Transmission and Multiplexing (TM).1 (2002-06) 1 Scope The present document specifies the architectural principles that should be applied for the design of synchronization networks that are suitable for the synchronization of Synchronous Digital Hierarchy (SDH) and Plesiochronous Digital Hierarchy (PDH) networks. • For a non-specific reference. Part 3-1: The control of jitter and wander within synchronization networks". It gives guidance and examples how these rules and architectural principles can be used to set up a synchronization scheme for various network configurations. Synchronous Digital Hierarchy (SDH). • For a specific reference. Generic requirements for synchronization networks. Synchronization network engineering". [3] [4] [5] [6] [7] [8] [9] ETSI . the latest version applies. It applies to the design of new synchronization networks. Part 1-1: Definitions and terminology for synchronization networks". Part 7-1: Timing characteristics of slave clocks suitable for synchronization supply to equipment in local node applications". It does not characterize existing synchronization networks based on PDH networks.g. Generic requirements for synchronization networks.2. through reference in this text. The present document specifies the rules and architectural principles the implementation of synchronization networks shall follow. subsequent revisions do not apply. Part 5-1: Timing characteristics of slave clocks suitable for operation in Synchronous Digital Hierarchy (SDH) equipment". This information is supplemented by EG 201 793 [7]. ETSI EN 300 462-5-1: "Transmission and Multiplexing (TM). ETSI EN 300 462-6-1: "Transmission and Multiplexing (TM).
but clocks in holdover mode can be used to synchronize clocks of the same quality. Higher quality clocks shall not be synchronized by lower quality clocks in holdover mode. The transport network may contain SECs. b) derive timing from a synchronization trail that is not supported by a SDH network. the abbreviations defined in EN 300 462-1-1 [1] and the following apply: 4 Synchronization methods Master-slave synchronization is appropriate for synchronizing SDH networks and the following material offers guidance on using this method.2. which can be connected in a synchronization distribution trail (see clause 8).7 ETSI EN 300 462-2-1 V1. 3. Master-slave synchronization uses a hierarchy of clocks in which each level of the hierarchy is synchronized with reference to a higher level. see EN 300 462-4-1 [6]. There are four qualities of clock in the synchronization hierarchy shown below: Primary Reference Clock (PRC): slave clock (transit node): slave clock (local node): SDH Equipment Clock (SEC): see EN 300 462-6-1 [5]. see EN 300 462-7-1 [8]. which avoids intermediate pointer processing. There are limits on the number of clocks.1 (2002-06) 3 3. ETSI .1 Definitions and abbreviations Definitions For the purposes of the present document. The distribution of timing between hierarchical node clocks shall be performed using a method. which may use the facilities of the transport network. This is a unilateral control scheme.2 ADM AIS NE OTN PDH ppm PRC PSTN SASE SDH SEC SETG SETS SSU SSM STM-N Abbreviations Add Drop Multiplexer Alarm Indication Signal Network Element Optical Transport Network Plesiochronous Digital Hierarchy parts per million Primary Reference Clock Public Switched Telephone Network Stand-Alone Synchronization Equipment Synchronous Digital Hierarchy SDH Equipment Clock SDH Equipment Timing Generator SDH Equipment Timing Source Synchronization Supply Unit Synchronization Status Message Synchronous Transport Module N For the purposes of the present document. Clock reference signals are distributed between levels of the hierarchy via a distribution network. The PRC is the highest quality hierarchical clock and the SEC is the lowest quality clock. the terms and definitions given in EN 300 462-1-1 [1] apply. see EN 300 462-5-1 [4]. Two possible methods are as follows: a) recover timing from a received Synchronous Transport Module N (STM-N) signal (this avoids the unpredictable effect of a pointer adjustment on the downstream slave clock). The master-slave method uses a single-ended synchronization technique with the slave clock selecting the synchronization trail to be used as its reference and changing to an alternative if the original trail fails.
or be a slave clock being synchronized to a high accuracy free running clock by terrestrial or satellite radio signals (e.g.2. The PRC equipment may either: implement its own free running oscillator (e. the SSU will use a high quality internal oscillator to maintain the stability and accuracy of the frequency of its output signals (holdover mode). A SSU is a logical function conforming to the requirements of EN 300 462-4-1 [6] or EN 300 462-7-1 [8].1 Functional description of clock types Primary Reference Clock (PRC) The PRC is a logical function conforming to the requirements of EN 300 462-6-1 [5].2 - Synchronization Supply Unit (SSU) accepts synchronization inputs from a number of sources. External reference timing signal (2 048 kHz or 2 048 kbit/s with SSM). (SASE)). integrated within Public Switched Telephone Network (PSTN) switch.g. filters this sources clock removing jitter and short-term wander. T1 T2 Select T3 T0 TG T4 SSU Key: T0: T1: T2: T3: T4: TG: Internal system clock. A functional diagram of the SSU is shown in figure 1. or as a stand-alone unit (a Stand-Alone Synchronization Equipment. Timing reference signal derived from 2 048 kbit/s input. GPS).8 ETSI EN 300 462-2-1 V1. It generates the master clock for a network or part of a network. Caesium tube oscillator). Timing Generator. Timing reference signal derived from STM-N input. NOTE 1: Where the SSU is integrated within a SDH Network Element (NE). Figure 1: The SSU clock function ETSI . Timing reference signal derived from 2 048 kHz or 2 048 kbit/s with SSM. NOTE 2: It may be possible to force the SSU into a free-running condition. The physical implementation of this function may be integrated within a SDH network element.1 (2002-06) 5 5. selects one of these inputs. T0 should be provided. 5. It: In the event of failure or degradation of all synchronization reference inputs. distributes the resultant clock to other elements within a node.
2. NOTE 2: It may be possible to force the SEC into a free running condition. Timing reference signal derived from 2 048 kHz or 2 048 kbit/s with SSM. filters this source's clock. The SEC: accepts synchronization inputs from a number of sources within that element. Timing reference signal derived from 2 048 kbit/s input.3 SDH Equipment Clock (SEC) The SEC is a logical function of input signal selection and clock filtering. Timing reference signal derived from STM-N input. selects one of these inputs. External reference timing signal (2 048 kHz or 2 048 kbit/s with SSM). NOTE 1: The SEC is a functional subset of the SETS as described in EG 201 793 [7]. Figure 2: The SEC clock function ETSI . The selection function conforms to the requirements of EN 300 417-6-1 [5] and the filtering function conforms to the requirements of EN 300 462-5-1 [4]. A functional diagram of the SEC is shown in figure 2.1 (2002-06) 5. SDH Equipment Timing Generator. In the event of failure of all synchronization reference inputs the SEC shall use its own internal clock as the active clock source (holdover mode).9 ETSI EN 300 462-2-1 V1. The SEC is specified to be used in SDH equipment as the timing source for the outgoing SDH STM-N interfaces of the NE. SETS Select Select T1 T2 Select T3 SETG T4 T0 SEC Key: T0: T1: T2: T3: T4: SETG: Internal system clock.
NOTE 2: Any interface used for synchronization of SDH NE should comply with the requirements given in EN 300 462-3-1 [2]. All other outputs from each node may be timed from the local SSU. excessive cascading of SSUs can be prevented. contains an SSU. only the clock of the highest hierarchical level in the node will recover timing from synchronization links from other nodes. This clause details the target architecture for SDH network synchronization. The distribution of synchronization can be categorized into intra-node within nodes containing a SSU and inter-node as follows: a) Intra-node distribution within nodes containing a SSU conforms to a logical star topology. Examples are given in EG 201 793 [7]. Evolutionary aspects are discussed in clause 10.2. The synchronization signals between the SSU and SECs will normally be 2 048 kHz or 2 048 kbit/s signals as described in EG 201 793 [7]. By considering the ring ADMs to belong to a synchronization trail rather than to the nodes where they are located. - NOTE 1: Network nodes can be configured without an SSU. An example illustrating this exception is given in the following: Assume that network timing has to be distributed along a ring structure where each node. All lower level network element clocks within a node boundary derive timing from the highest hierarchical clock level in the node. Apart from these network elements.10 ETSI EN 300 462-2-1 V1. Timing is distributed from network elements within the boundary to network elements beyond the boundary via the SDH transmission medium. An exception may be made for the network element clock that carries the synchronization trail to the SSU. SEC * Synchronization link(s) Node clock * * SEC SEC * Logical node boundary * SEC * Logical timing Figure 3: Synchronization network architecture for intra-node distribution ETSI . The relationship between clocks within a node is shown in figure 3. in addition to the ring ADM.1 (2002-06) 6 Synchronization network architecture The architecture employed in SDH requires the timing of all network element clocks to be traceable to a PRC.
With this architecture. pseudo-synchronous. These are: In synchronous mode. the distribution network shall be designed such that. plesiochronous. This is the normal mode of operation within a single operator's domain or within a sub-network of a single operator's domain. When none exist. the node clock shall enter holdover mode. Phase reference information is transferred between synchronization nodes by means of a synchronization trail.2. The hierarchical relationship between clocks is shown in figure 4. even under fault conditions. PRC: Primary Reference Clock PRC SSU SSU SSU SSU SSU SSU Figure 4: Synchronization network architecture for inter-node distribution Clocks of a lower hierarchical level shall have a pull-in range which ensures that they can automatically acquire and lock to the timing signal generated by the same or higher level clock that they are using as a reference. one or more link connections each supported by a multiplex section trail are recommended to conform to the requirement given in clause 4. 7 - Synchronization modes synchronous.11 ETSI EN 300 462-2-1 V1. The sub-network connections (switches) in the synchronization trail need to be set to maintain only valid hierarchical relationships between clocks. To ensure that this relationship is preserved. When the distribution network is based on SDH. Pointer adjustments will only occur randomly. The synchronization trail is provided by one or more synchronization link connections each supported by a synchronized PDH trail or a SDH multiplex section trail or each synchronization trail derived directly from a PRC. all clocks in the network will be traceable to a single PRC. Four synchronization modes can be identified. ETSI .1 (2002-06) b) Inter-node distribution conforms to a tree-like topology and enables all the nodes in the SDH network to be synchronized. only valid higher-level references are presented to hierarchical clocks. it is important for the correct operation of the synchronization network that clocks of lower hierarchical level only accept timing from clocks of the same or higher hierarchical level and that timing loops are avoided. When a trail becomes disabled then the node clock shall select another reference from a set of valid alternatives. asynchronous.
NOTE: In a large single operator domain where more than one PRC is used. However. If synchronization is lost to the last network element in the SDH network connection (or the penultimate network element in the case where the last one is slaved. However to determine synchronization clock requirements. pointer adjustments will be generated in the network elements at the boundary between equipment synchronized to different PRC. However. The longest chain should not exceed K SSUs with up to N SECs interconnecting any two SSUs. not all clocks in the network will have timing traceable to the same PRC. In plesiochronous mode. The value of N is limited by the quality of timing required by the last network element in the chain and ensures the short-term stability mask of EN 300 462-3-1 [2] is met. If synchronization is lost to a gateway SDH network element performing asynchronous mapping. Pointer movement at the intermediate network element will be corrected by the next network element in the connection. the synchronization trail and the fallback alternatives to one or more clocks in the network will have been disabled. this will not result in a net pointer movement at the final output gateway network element provided the input gateway network element remains synchronized to the same PRC. the frequency offset and drift of the clock will cause pointer adjustments at the next SDH network element in the SDH network connection. consists of a loop-timed multiplexer). e. The values of K and N have been derived from theoretical calculations and practical measurements are required for their verification. This is the normal mode of operation for the international and inter-operator network.2. the number of network elements in tandem should be minimized. The clock will enter holdover or free-run mode. ETSI . The SDH network is not required to maintain traffic when the clock accuracy is less than that of a SEC.1 (2002-06) In pseudo-synchronous mode (see note). therefore.g. there will also be pointer adjustments to cater for at the SDH network output. this mode of operation may be employed. A clock accuracy of ±20 ppm is required to send an Alarm Indication Signal (AIS) (applicable for regenerators and any other SDH equipment where loss of all synchronization inputs implies loss of all traffic). if the synchronization failure occurs at an intermediate network element. In general. Asynchronous mode corresponds to the situation where large frequency offsets occur. N = 20 with the total number of SECs limited to 60. 8 Synchronization network reference chain The synchronization network reference chain is shown in figure 5. these pointer adjustments will propagate to the end of the network connection. each PRC will comply with EN 300 462-6-1 [5] and. which is still synchronized. the values for the worst case synchronization reference chain are K = 10. Timing is distributed via master-slave synchronization from the PRC to all clocks in the chain. the quality of timing will deteriorate as the number of synchronized clocks in tandem increases and hence for practical synchronization network design.12 ETSI EN 300 462-2-1 V1.
13 ETSI EN 300 462-2-1 V1.1 (2002-06) PRC N x SECs 1st Slave K-1th Slave For worst-case scenario calculation purposes: K = 10 N = 20 with restriction that the total number of SECs is limited to 60.2. Figure 5: Synchronization network reference chain ETSI . N x SECs Kth Slave SSU N x SECs NOTE: It is possible for the PRC to be connected directly to an SSU without an intervening SEC.
This requires careful planning to ensure that network synchronization is not jeopardized. Timing within the SDH network should follow the master-slave approach.1 (2002-06) 9 9. steps shall be taken so that synchronization links supported by primary rate PDH trails do not transit the SDH network. Where a network is completely SDH based. both SSUs and SECs may have to reconfigure and recover timing from one of their alternate synchronization trails. This will ensure that a SEC rarely enters holdover or free-run mode. by automatic reconfiguration capability in SDH sub-networks using the SSM protocol. During the evolution of the network to SDH.2. This requires a reconfiguration of the synchronization architecture since all synchronization links transiting the SDH network shall be supported on SDH multiplex section trails.2 Optical Transport Networks The payload transport performance in the Optical Transport Networks (OTN) is timing transparent in the sense. When SDH equipment is initially introduced.14 ETSI EN 300 462-2-1 V1. Thus the basic STM-N synchronization trails and the STM-N synchronization trails over OTUk trails are of equivalent synchronization performance. the synchronization distribution will be determined solely by the synchronization network reference chain. Interworking between SASEs and SDH NEs is described in annex B of EG 201 793 [7]. by synchronization network management supporting reconfiguration at the overall network level. To effect this. The network elements can be integrated into existing synchronization hierarchies. all network elements will seek to recover timing from the highest hierarchical level clock source available. Where possible synchronization trails should be provided over diversely routed paths. the network synchronization plan will have to be altered to accommodate the SDH network elements. the use of a squelching function or AIS may be required.1 Synchronization network evolution SDH networks The SDH is designed to operate in pseudo-synchronous mode. utilizing redundant synchronization trails where possible. the gateway network element shall be timed from either the PRC or an existing SSU. 9. However. In the event of a failure of synchronization distribution. If the SDH network introduction results in PDH islands. In order to indicate faults in the synchronization distribution network across non-SDH interfaces. The slave clock shall reconfigure to recover timing from an alternative trail if the original trail fails.1 - Synchronization network robustness General Synchronization network robustness can be achieved through different and complementary methods: by careful design of the synchronization network. it may have to recover timing from a SSU. which is itself in holdover if this is the highest hierarchical level source available to it. that wander added to the payload does not exceed the limits as defined in EN 300 462-3-1 [2].2 Trail redundancy It is preferable that all SSUs and SECs are able to recover timing from at least two synchronization trails. ETSI . 10 10. 10.
then it needs to have the capability to communicate to the SDH NEs either directly or by means of the SDH network management system. The quality marking scheme provides an indication of the quality of the timing using a status messaging approach The SSM is transported in the section overhead (S1 byte) as described in EN 300 147 [3] and EN 300 417-6-1 [9]. ETSI . should be carefully considered to avoid any degradation of synchronization distribution such as timing loops. timing is distributed between network nodes via a number of network elements with clocks of lower hierarchical level. So consequences of change to the network or an equipment configuration. fault detection. potential problems have been identified. PRC PRC Timing recovery 1st NE 2nd NE Timing recovery 1st NE 2nd NE Nth NE Before recovery SSU Nth NE After reconfiguration SSU Figure 6: Reconfiguration example 10. To provide an example of a reconfiguration. It shall therefore be possible to restrict the links used for synchronization.3 Synchronization status message Within SDH sub-networks.2. the status message shall reflect the selected reference.1 (2002-06) 10. As far as possible. This is shown in figure 6. the Synchronization Status Message (SSM) is provided to allow selection and confirmation of the highest quality synchronization trail available to SECs (in normal operation and during synchronization failure conditions) through a priority/quality level algorithm described in EN 300 417-6-1 [9]. Network synchronization planners are reminded that careful consideration is needed when using timing quality markers. it should reconfigure and accept timing from the SSU. network topology. Such a management system covers configuration of equipment.4 Management The management system is an important component in ensuring the robustness of the synchronization network utilizing its ability to actively monitor the actual working state of the synchronization network and of its different components. no disturbance of the normal timing distribution should be introduced. It is also important that access to synchronization network management should be secured by different enabling levels from the mere reading of event logs to network and equipment configuration. if the first network element from the PRC loses its synchronization trail from the PRC. Synchronization management may allow remote actions on synchronization equipment and network topology.15 ETSI EN 300 462-2-1 V1. If it is extended to SECs. Synchronization management can be restricted to PRC and SSU in an independent system or integrated in the SDH network management system. For outputs used for timing distribution using SSM. A timing quality marking scheme. Where timing quality markers are used in a meshed network. troubleshooting.
2.1 (2002-06) Annex A (informative): Bibliography ITU-T Recommendation G. ETSI .16 ETSI EN 300 462-2-1 V1.783: "Characteristics of synchronous digital hierarchy (SDH) equipment functional blocks".
1 V1.2 V1.1.1 V1.2.2.1 September 1996 May 1998 August 1999 January 2002 June 2002 Publication as ETS 300 462-2 (Withdrawn) Publication Publication One-step Approval Procedure Publication OAP 20020531: 2002-01-30 to 2002-05-31 ETSI .1.2.1 (2002-06) History Document history Edition 1 V1.17 ETSI EN 300 462-2-1 V1.
Documents Similar To Synchronization Network Architecture Based on SDH
REAL HUMAN FACE DETECTION FOR SURVEILLANCE SYSTEM USING HETEROGENEOUS SENSORS