ATIS 0300231 04-2013 SONET - Layer 1 In-Service Digital Transmission Performance Monitoring.pdf

1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0300231.04.2013 SONET LAYER 1 IN-SERVICE DIGITAL TRANSMISSION PERFORMANCE MONITORING As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the industrys most-pressing busine

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8、tandards. The American National Standards Institute does not develop standards and will in no circumstances give an interpretation of any American National Standard. Moreover, no person shall have the right or authority to issue an interpretation of an American National Standard in the name of the A

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10、 Standards Institute require that action be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of American National Standards may receive current information on all standards by calling or writing the American National Standards Institute. Notice of Disclaimer It describes

11、 the functions related to the collection, storage, thresholding, and reporting of PM information; and It establishes the PM functions that may be used at network interfaces between telecommunication carriers, at network boundaries, and at customer premises to permit compatible maintenance operations

12、. Although this standard establishes ranges over which transmission performance can be measured, it does not establish any requirements or guidelines for levels of performance. This standard refers to other American National Standards that address digital transmission and performance criteria. ATIS-

13、0300231.04.2013 2 2 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to ag

14、reements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. ATIS-0900102.1993 (2010), Digital hierarchy Electrical interfaces.1ATIS-0900105.2008 (R2013), Synchronous Optical Network (SONET) Bas

15、ic Description including Multiplex Structures, Rates, and Formats.1ATIS-0900105.a.2010, Addendum to ATIS-0900105.2008 to include the Muti-lane Interface and Correct the Extended Line DCC Location Specification for STS-768.1ATIS-0900105.02.2007 (R2012), Synchronous Optical Network (SONET) Payload Map

16、pings.1ATIS-0900105.05.2002 (R2013), Synchronous Optical Network (SONET): Tandem Connection Maintenance.1ATIS-0900105.07.1996 (R2008), Synchronous Optical Network (SONET) Sub STS-1 Interface Rates and Formats Specifications. withdrawn2ATIS-0900105.07a.1997 (R2008), Synchronous Optical Network (SONET

17、) Sub STS-1 Interface Rates and Formats Specifications (inclusion of N x VT Group Interfaces). withdrawn2ATIS-0600107.2002 (R2011), Digital Hierarchy - Formats Specifications.1ATIS-0600107.a.2005 (R2010), Digital Hierarchy Formats Specification (Virtual Concatenation and LCAS).1ATIS-0300231.2013, Di

18、gital Hierarchy Layer 1 In-Service Digital Transmission Performance Monitoring.13 Definitions or (ii) two section terminating equipments. A section terminating point is the point where the physical medium is separated from the digital signal. PM is accomplished after signal regeneration where applic

19、able. Performance monitoring at the section layer is based on the SONET framing structure and Bit Interleaved Parity (BIP) measurements applicable at this layer. The line portion of a transmission facility, including the terminating points, exists between two LTEs. Each of the LTEs originates the li

20、ne signal and terminates the line signal between each other. Performance monitoring at the line layer, where applicable, is accomplished via Alarm Indication Signal (AIS) and BIP measurements applicable at this layer. The path layer represents a logical connection between two path terminating equipm

21、ents (PTE). The PTEs each originate and terminate the payload envelope frame for the signal at the given rate. Performance monitoring at the path layer, where applicable, is accomplished via AIS, pointer, configuration signals, and BIP measurements applicable at this layer. The tandem connection sub

22、-layer is defined as a bundle of STS-1s or STS-Ncs which are common to the transport and managed together through one or more tandem line systems, with the constituent SPE payload capacities unaltered. In the layered overhead approach used in SONET, the tandem connection sub-layer falls between the

23、STS-path and OC-line overhead layers. This sub-layer deals with the reliable transport of Path layer payload and its overhead across a network (e.g., a purpose of the tandem connection sub-layer is to provide network level maintenance functions). LTEs functioning as tandem connection terminating equ

24、ipment may read and interpret all of the path overhead but modify only certain overhead byte(s). As shown in Figure 2 and defined above, the path layer provides end-to-end connectivity. The tandem connection layer may provide common maintenance functions for multiple path entities carried as a singl

25、e bundle. The line layer provides connections ATIS-0300231.04.2013 6 between two LTE NEs while the section layer provides the ability to segment line entities into smaller, more manageable pieces. A line entity can traverse multiple section entities, a tandem connection entity may cross multiple lin

26、e entities, and a path entity can traverse multiple line entities and tandem connection entities if implemented. VT1.5 and VT Group (VTG) are sub-STS-1 interfaces (SONET interfaces at rates less than STS-1). VT1.5 and VTG interfaces each combine the SONET section and line layer functions and overhea

27、d into the one functional layer the line layer. The following performance primitives and parameters are sufficient to describe the performance of both the electrical and optical SONET interfaces, as well as the sub-STS-1 interfaces, VT1.5 and VTG, as described above. 4.1 Abbreviations an “L“ indicat

28、es the Line entity; a “P“ indicates the Path entity; and a “V“ indicates the VT entity for SONET. Items defined for near-end monitoring have no additional suffixes, while far-end items append “FE“ to the entity suffix. For example, ES-P designates near-end Errored Seconds at the path (STS) layer, wh

29、ile ES-PFE designates the same parameter for the far-end. For the VT layer, a “V“ is used instead of a “P.” 4.2 Performance Primitives Table 1 and Table 2 summarize the performance primitives that are judged to be useful for in-service PM. SONET primitives are shown in the SONET columns of the table

30、, and are described in this sub-clause. Support of the primitives in a network element is indicated in the table as: required (R), application specific (A), or optional (O). See also clause 5. 4.2.1 Performance Anomalies (All Entities) 4.2.1.1 Error Detection Code (EDC) An EDC is an N-bit code gener

31、ated by the transmitting equipment over a specified portion of the signal. For SONET, this N-bit code consists of a bit interleaved parity check (BIP-N). The first bit of the code provides even parity over the first bit of all N-bit sequences in the covered portion of the signal, the second bit prov

32、ides even parity over the second bits of all N-bit sequences within the specified portion, etc. Even parity is generated by setting the BIP-N bits so that there are an even number of 1s in each position of all N-bit sequences including the BIP-N. EDC errors result from BIP-N errors and can be regist

33、ered in one of two ways. 1. BIP-N errors 2. Block errors (BE) In either case, the errors shall be termed EDC errors. ATIS-0300231.04.2013 7 BE or BIP-N errors shall be used to implement EDC errors at the line, tandem connection, and path layers.3At the section, VT line, and VTG line BEs are not defi

34、ned and are for further study. An implementation should avoid the configuration of NEs that use differing EDC error registering methods to the same transmission entity (layer). 4.2.1.1.1 BIP-N Error BIP-N errors are detected at each entity layer of the incoming signal. Each BIP-N can detect up to N

35、errors per frame and each parity bit of a BIP-N found to be errored is registered separately in a count of EDC primitives per unit time. 4.2.1.1.2 Block Error (BE) A block error is counted when any of the N parity bits in a BIP-N is found to be errored. There will, by definition, be a greater than o

36、r equal number of BIP-N errors per unit time than BEs. The ratio of BIP/BE will be between 1 and N. Where randomly distributed errors are insufficient to cause an SES, this ratio is approximately 1. As the error rate increases, this ratio will approach approximately N/2. 4.2.1.1.3 BIP-8 errors TC AI

37、S/LOP defect; TC AIS failure; TC LOP failure; TC Idle signal received condition; TC Test signal received condition; and TC Count Type Indicator (CTI). The definition of the parameters in the TC-PRM will be defined in the appropriate sub-clauses below. 4.2.1.3 Pointer Adjustment Anomalies When an STS

38、 SPE is transported through a SONET network, the alignment of the SPE within the STS may slip backward or forward in time as a result of differences in the frequencies of the clocks in the various NEs that pass or process that SPE. The alignment of the SPE will be denoted by the value of a pointer a

39、nd the pointer will change in value (pointer movement or pointer justification) to show the changing relationship between the SPE and the STS. A pointer movement is flagged in the overhead bytes as described in ATIS-0900105.2008 (R2013). A pointer movement in a network intended primarily for synchro

40、nous transmission is an event of note (although it is not necessarily signal degrading unless an excessive number, of a particular type, occur in a specified period of time) and therefore primitives (anomalies) and parameters have been developed to record such events. When an NE detects a pointer mo

41、vement in an incoming STS-to-SPE relationship, a detected pointer movement anomaly is counted. The value of the incoming pointer is used to properly detect and remove the SPE from the received STS. If the received SPE is to be transmitted onward in another STS (which may be either an internal signal

42、 within the NE or an STS that will appear in a signal at one of the NEs external SONET interfaces), a pointer in the overhead of that STS will flag the alignment between the SPE and the STS. Pointer movements which the NE must generate to properly align the SPE with the STS result in the counting of

43、 a generated pointer movement anomaly. Note that in the general case for a particular NE, the incoming STS, the outgoing STS, and the SPE passed from one to the other may have been timed from different system clocks. In such a case, detected pointer movements and generated pointer movements may both

44、 occur but there will be no deterministic relationship between the two. Also note that pointer justifications are not necessarily indicative of jitter performance. 5Since there is only 1 bit for the REI-V, REI-V counts may not be identical to CVs counted at the far end. ATIS-0300231.04.2013 10 Param

45、eters have been developed and included in this standard to record the number and frequency of both detected and generated pointer movement anomalies. In addition, parameters have been included to record the differences between generated and detected pointer movement parameters. Although there may be

46、 no relationship between such events, the differences between them will often be of value in locating system timing problems. Similar relationships to those described above for STSs and STS SPEs exist between virtual tributaries (VT) and VT SPEs. These are handled by VT pointers, and primitives and

47、parameters for VT pointers are also provided in this standard. Pointer adjustment anomalies apply to STS and VT paths. A “P“ or a “V“ will be prefixed to either “Gen“ or “Det“ in the name of a particular anomaly to indicate its source. Those letters will be omitted from the definitions in this secti

48、on for brevity. 4.2.1.3.1 PJ-Generated Definition A generated pointer movement occurs when an NE performs a valid increment or decrement operation as defined in ATIS-0900105.2008 (R2013). This operation is performed in two cases: 1. The NE must move a pointer to reconcile a frequency difference betw

49、een an SPE and its output STS. 2. The NE must move a pointer to reconcile a frequency difference between an SPE and the local clock when an SPE must be desynchronized locally subsequent to local pointer processing. 4.2.1.3.1.1 Positive Pointer Justification - Generated (PPJ-Gen) A PPJ-Gen occurs when the generated pointer value is incremented by one. 4.2.1.3.1.2 Negative Pointer Justification - Generated (NPJ-Gen) A NPJ-Gen occurs when the generated pointer value is decremented by one. 4.2.1.3.2 PJ-Detected Definition A detected pointer movem