ANSI ATIS 0100514-2009 Network Performance Parameter and Objectives for Dedicated Digital Services C SONET Bit Rates.pdf

1、 AMERICAN NATIONAL STANDARD FOR TELECOMMUNICATIONS ATIS-0100514.2009(R2014) Network Performance Parameters and Objectives for Dedicated Digital Services SONET Bit Rates As a leading technology and solutions development organization, ATIS brings together the top global ICT companies to advance the in

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11、 of Disclaimer transition to the available state occurs at the beginning of 10 consecutive seconds, none of which is an SES. 3.1.2 Background Block Error (BBE): An errored block not occurring as part of an SES. 3.1.3 Bit Error Ratio (BER): The ratio of the number of bit errors to the total number of

12、 bits transmitted in a given time interval. 3.1.4 Block: A block is a set of consecutive bits associated with the connection; each bit belongs to one and only one block. See clause 5 for block sizes used in accessing performance. 3.1.5 Errored Block (EB): A block in which one or more bits are in err

13、or. See Annex A for estimators. 3.1.6 Errored Second (ES): A one second period with one or more errored blocks. SES defined in 3.1.11 is a subset of ES. See Annex A for estimators. NOTE A period of loss of signal shall be considered a period of errored blocks. 3.1.7 Error Free Second (EFS): A one se

14、cond interval in which no errored blocks are received. NOTE In general, measurement is over time and is stated as a percentage, i.e., % EFS. 3.1.8 Inter-Network Interface (INI): The point of demarcation between access and transit portions of the network. NOTE Where a Point of Termination (POT) exist

15、s, it coincides with an INI. 3.1.9 Network Interface (NI): The point of demarcation between the service provider facilities and the customers installation. NOTE Customer, in this definition, refers to the end user. 3.1.10 Pseudo-Random Binary Sequence (PRBS): A binary sequence that approximates a ra

16、ndom signal. The PRBS pattern is 2n-1 bits in length and generates every combination of n-bit words as defined in ANSI/IEEE 1007. 3.1.11 Severely Errored Period (SEP): A sequence of between 3 to 9 consecutive SES. The sequence is terminated by a second which is not an SES. 3.1.12 Severely Errored Se

17、cond (SES): A one-second period that contains 30% errored blocks or at least one severely disturbed period. A severely disturbed period occurs when, over a period of time equivalent to 1 ms, all the contiguous blocks are affected by a high bit error density. See Annex A for estimators. 3Other indica

18、tors are for further study. ATIS-0100514.2009 3 NOTE A period of loss of signal or a bit error density of 10-2shall be considered a period of errored blocks with high bit error density. It is not required to verify this BER by an actual in-service or out-of-service measurement. 3.2 Acronyms each bit

19、 belongs to one and only one block. The following block sizes are given in assessing performance. (See Table 1.) Table 1 - Block Size Rate (Mbit/s) 51.84 (STS-1) 155.52 (STS-3c) 622.08 (STS-12c) 2,488.32 (STS-48c) 9,865.28 (STS-192c) Bits/block 6,264 18,792 75,168 300,672 1,202,688 The block size co

20、rresponds to the number of bits in 125 microseconds for the SONET path (equivalent to synchronous payload envelope (SPE); 50.112 Mbit/s, 150.336 Mbit/s, 601.344 Mbit/s, 2.405 Gbit/s, and 9.622 Gbit/s for STS-1, STS-3c, STS-12c, STS-48c, and STS-192c paths, respectively. A path that is multiplexed to

21、 a higher rate should be measured at its demultiplexed, original rate. Performance objectives apply at these rates to the SONET path that is not constrained to a particular physical signal type (i.e., objectives apply for electrical (STS-n) or optical (OC-n) signals). See Annex A for further details

22、 on block measurement with SONET path measures. 5.2 Error Performance Parameters Performance parameters include: 5.2.1 Percent Errored Seconds (% ES): 100 the ratio of ES to total seconds in available time during a fixed measurement period. 5.2.2 Percent Severely Errored Seconds (% SES): 100 the rat

23、io of SES to total seconds in available time during a fixed measurement period. 5.2.3 Background Block Error Ratio (BBER): The ratio of Background Block Errors (BBE) to total blocks in available time during a fixed measurement interval. No blocks that occur during an SES shall be used for the comput

24、ation of BBER. ATIS-0100514.2009 5 5.2.4 Severely Errored Period Intensity (SEPI): The number of SEP events in available time, divided by the total available time. NOTE - The SEPI parameter has a unit of (1/s). This is to enable any SEPI objective to be easily translated to the equivalent number of

25、SEP events over a specific measurement interval. It should be noted that the SEP event has no significance over a time interval of less than three seconds. 6 DERIVATION OF END-TO-END OBJECTIVES Because of the variability of performance, objectives must be determined with due consideration of the sta

26、tistical distribution of the impairments in the individual provider portions. In general, error performance distributions have two components: a Poisson-like distributed background bit error rate; episodes of clustered error events superimposed on the above. Most modern digital systems have been eng

27、ineered such that the Poisson component is low relative to objectives. The episodic component is difficult to model, but for todays architecture, facilities, and equipment, certain statistical properties are observed. There is a low probability that all provider portions would simultaneously operate

28、 at the worst end of their individual performance distribution. Thus, it follows that the end-to-end performance objectives will be greater than the largest objective among the carrier portions, but less than the linear sum of the objectives of all portions. The end-to-end objective in each case was

29、 chosen between these bounds according to current network behavior. For example, in the case where the accuracy objectives are all the same on all three portions, an end-to-end objective equal to a factor 2 times the objective on the individual carrier portions was chosen. 7 PERFORMANCE OBJECTIVES A

30、ccuracy and availability performance objectives provide a measure for evaluating performance of digital services. They can be used as an aid in designing, developing, and maintaining the networks providing digital services, and also, should be considered in the design of terminal equipment and servi

31、ce applications. 7.1 Rationale Objectives are provided for the performance parameters defined in clause 5. Services in aggregate provided in accordance with this standard should perform better than the objective. However, individual circuit performance may vary as a result of factors such as technol

32、ogy mix, system architecture (including protection strategies) and complexity, geographic factors, isolated events, etc., and may be time variant (i.e., could exceed objectives one or two days per month). Many factors were taken into account in deriving these objectives: customer needs, analytical e

33、stimates of performance, empirically observed network performance, performance requirements of the service and its applications, and the practicality of implementing and maintaining a desired quality of service. 7.2 Accuracy objectives Accuracy performance objectives are stated in terms of the param

34、eters provided in Table 2. Accuracy performance should be evaluated relative to a measurement period of 30 days or more. As determination of compliance with the performance objectives would require excessively long test periods, the objectives are used to derive limits for timed tests. Background Bl

35、ock Error Ratio (BBER), ATIS-0100514.2009 6 Percent Errored Second (% ES), and Percent Severely Errored Second (% SES) characterize the transmission quality of the service and are used to derive the test limits. Specific intervals and values are identified in clause 9. The long term accuracy objecti

36、ves are expressed as a ratio (or percentage) because they apply over long periods of time. For convenience, percentage values may be converted to a mean number of events/day through multiplication by 864 (86,400 sec/day100). Table 2 - Long-term Accuracy Objectives Segment Parameter 51.84 Mbit/s (STS

37、-1) 155.52 Mbit/s (STS-3c) 622.08 Mbit/s (STS-12c) 2.488 Gbit/s (STS-48c) 9,865 Gbit/s (STS-192c) End-to-End BBER (Note 1) (Note 1) 10-5 10-5 10-4 % ES 0.25 0.5 (Note 2) (Note 2) (Note 2) % SES 0.035 0.035 0.035 0.035 0.035 SEPI (Monthly) FFS FFS FFS FFS FFS Transit BBER (Note 1) (Note 1) 5 x 10-6 5

38、 x 10-6 5 x 10-5 % ES 0.125 0.25 (Note 2) (Note 2) (Note 2) % SES 0.025 0.025 0.025 0.025 0.025 SEPI (Monthly) FFS FFS FFS FFS FFS Access BBER (Note 1) (Note 1) 5 x 10-6 5 x 10-6 5 x 10-5 % ES 0.125 0.25 (Note 2) (Note 2) (Note 2) % SES 0.01 0.01 0.01 0.01 0.01 SEPI (Monthly) FFS FFS FFS FFS FFS (Th

39、ere may be periods of time when these objectives are not met.) NOTES 1 BBER is only specified for rates above 160 Mbit/s. 2 Percent ES objectives tend to lose significance for applications at high bit rates and are therefore not specified for paths operating at bit rates above 160 Mbit/s. Neverthele

40、ss, it is recognized that the observed performance of synchronous digital paths is error free for long periods of time even at Gigabit/s rates; and that significant ESR indicates a degraded transmission system. Therefore, for maintenance purposes ES, monitoring should be implemented within any error

41、 performance measuring devices operating at these rates. 3 SEPI is a new parameter, with little history. As such, specific objectives are for future study (FFS). 7.3 Availability Objectives Availability objectives are stated in terms of the parameter provided in Table 3. Percent (%) Availability cha

42、racterizes the usability of the service over time. See 3.1.1 for available state definition and transitions. ATIS-0100514.2009 7 Table 3 - Service Availability Objectives Segment Parameter 51.84 Mbit/s (STS-1) 155.52 Mbit/s (STS-3c) 622.08 Mbit/s (STS-12c) 2.488 Gbit/s (STS-48c) 9,865 Gbit/s (STS-19

43、2c) End-to-End % Availability (Annual) 99.830 99.830 99.830 99.830 99.830 Transit % Availability (Annual) 99.930 99.930 99.930 99.930 99.930 Access % Availability (Annual) 99.950 99.950 99.950 99.950 99.950 8 TEST DESIGN 8.1 Rationale Test procedures described in this standard are intended to indica

44、te, by comparing measured performance against threshold values, whether or not a particular circuit is likely to meet the service performance objectives specified in this standard. A circuit that passes these tests is considered “acceptable”; if it does not pass these tests, it is considered “unacce

45、ptable.” For the test specified, all measurements are to be made at the bit rate of the service. Non-intrusive measurement methods may be used where available. Out-of-service tests conducted intrusively in accordance with clause 9 should employ block based measurements with the appropriate rate PRBS

46、 for the payload.4These procedures take into account the duration of a test trial and the number of trials to be run. Both long duration and short duration tests are specified. Test limits are derived from long term accuracy objectives through statistical and empirical procedures. Tests are provided

47、 for bringing an overall circuit5into service, either on completion of a new installation (acceptance) or after repair activity (repair verification). Performance studies of current transmission technologies have shown that error distributions are such that long observation periods (i.e., 30 or more

48、 days) are required to indicate long term accuracy performance with a high degree of statistical confidence. However, practical considerations require much shorter duration tests (i.e., 24 hours or less) which provide a prediction of long term performance. For short duration (1 to 2 hour) tests, lim

49、its are provided for stages of a sequential test procedure. If at the conclusion of any stage in the procedure, the test result is less than or equal to the test limit, the service performance shall be considered acceptable and the test terminated. If at any stage in the procedure the test result is greater than the test limit for the final stage, the service performance shall be considered unacceptable and the test similarly terminated. If the test result at any stage is between these two limits, the test is thus far inconclusive and shall be continued to the s