What is the pF_DS (Far-End Defect Second) Performance-Monitoring Parameter for the ODUk Layer?

This blog post breifly defines the pF_DS (Far-End Defect Second) Performance Monitoring paramteter that the OTN PTE will compute and generate.

This blog post aims to briefly define and describe the pF_DS (Far-End Defect Second) Performance Monitoring parameter that the OTN PTE (or ODUk_TT_Sk Atomic Function) will compute and generate.

The OTN PTE (or ODUk_TT_Sk function) will include information on pF_DS without each Performance Monitoring report that it sends to System Management.

Performance Monitoring Reports

NOTES:

  1. The OTN STE (OTUk_TT_Sk Atomic Function) also monitors and generates information on the pF_DS (Far-End Defect Second) parameter at the OTUk Layer. Please see the pF_DS at OTUk Layer Post for more details on this parameter.
  2. Throughout this post, I will be using the terms: OTN PTE and ODUk_TT_Sk Function interchangeably. In the context of this blog post, these two terms mean the same thing.

Introduction

At the ODUk Layer, the OTN (Sink) PTE is the entity that is responsible for detecting and reporting Far-End Defect Second events.

As the OTN PTE receives and monitors its incoming ODUk signal, it will check for many things. It will continuously check for the incoming ODUk signal for Service-Affecting Defect (e.g., dAIS, dOCI, dLCK, dTIM, etc.) as well as bit (or symbol) errors (e.g., PM-BIP-8 errors and PM-BEI errors).

Another thing that the OTN PTE will do (as it continuously monitors its incoming ODUk signal) is to divide each second of (monitoring) time into the following two categories:

  • Far-End Available (Working) Seconds, and
  • Far-End Defect Seconds

Anytime the OTN PTE detects and categorizes a given one-second period as being a Far-End Defect Second, it will increment the pF_DS parameter and report that information to System Management.

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So When does the OTN PTE detect and flag a given One-Second Period as being a “Far-End Defect Second”?

ITU-T G.798 presents the following Performance Monitoring Equation for the ODUk_TT_Sk function.

pF_DS <- dBDI

Where:

dBDI is the current state of the ODUk-BDI or the Backward Defect Indicator Defect (at the ODUk Layer).

The OTN PTE (or ODUk_TT_Sk function) will continuously evaluate the above equation as it monitors its incoming ODUk signal.

This equation states that the OTN PTE will declare a given one-second period as being a Far-End Defect Second if it has declared the dBDI defect condition during any portion of that one second.

A given OTN PTE will declare a one second period as a Far-End Defect Second if the remote OTN PTE declares any of the following defect conditions:

  • dAIS (ODU-AIS)
  • dOCI
  • dLCK
  • dTIM

In this case, the OTN PTE will increment the pF_DS parameter for each one-second period that it categorizes as a Far-End Defect Second.

Conversely, the OTN PTE will declare a one-second period as an Available Second, if the remote OTN PTE is not declaring any of the above-mentioned defects. The OTN PTE will NOT increment the pF_DS parameter in this case.

What Does This Mean in English?

Of course, if the OTN PTE declares the dBDI defect condition, then this also means that the remote PTE is declaring a service-affecting defect condition. In other words, the pF_DS parameter reflects the health of the remote (or Far-End) terminal.

If the remote terminal declares no service-affecting defects, then the near-end terminal will not increment the pF_DS parameter. On the other hand, if the remote terminal declares a service-affecting defect, then the near-end terminal will increment the pF_DS parameter.

So, if the ODUk_TT_Sk function has declared the dBDI defect condition for even a fraction of a given one-second period, it will declare it as a Far-End Defect Second. It will also set the parameter pF_DS to 1 and report that information to System Management.

Conversely, if the OTN PTE determines that the ODUk_TT_Sk function did not declare the dBDI defect condition at all during a given one-second period. In that case, it will declare that one-second period is a Far-End Available (Working) Second. In this case, the OTN STE will NOT set the parameter pF_DS to 1.

Hence the pF_DS parameter reflects the network’s health at the remote terminal (e.g., the other end of the ODUk Path).

Is there such a thing as a Near-End Defect Second?

Throughout this post, we have used the term: Far-End Defect Second. Does this mean that there is another parameter called Near-End Defect Second?

Answer: Yes, there is such a parameter. See the Near-End Defect Seconds (pN_DS) post at the ODUk Layer for more details.

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OTN – Lesson 10 – Video 3N – The OTUk/ODUk_A_Sk and ODUk_TT_Sk Atomic Functions

This post presents the 3rd of the 7 Videos that covers training on the Peformance Monitoring of the ODUk Layer (for Non-Multiplexed Applications). This post focuses on the Sink Direction ODU-Layer Atomic Functions.

OTN – Lesson 10 – Video 3N – The OTUk/ODUk_A_Sk and ODUk_TT_Sk Atomic Functions

This post contains a video that begins our discussion of the Receive (or Sink) Direction circuitry.  

In particular, this video covers the following Atomic Functions.

  • The OTUk/ODUk_A_Sk Atomic Function, and
  • A portion of the ODUk_TT_Sk Atomic Function.

This video covers the following features associated with the ODUk_TT_Sk Atomic Function.

  • Checking for Near-End Errors (e.g., PM-BIP-8 Errors)
  • Checking for Far-End Error Counts (e.g., PM-BEI)

This video also discusses how the ODUk_TT_Sk function will declare and clear the PM-dBDI (Backward Defect Indicator) defect condition.  

Continue reading “OTN – Lesson 10 – Video 3N – The OTUk/ODUk_A_Sk and ODUk_TT_Sk Atomic Functions”

Lesson 2 – ODU Framing

This post provides a comprehensive review and video training of the ODU frame and its overhead fields.

Lesson 2 – ODU (Optical Data Unit) Frame Training

This post presents a video that discusses the ODU (Optical Data Unit) Frame in considerable detail.  

In addition to discussing the ODU frame format, this video also discusses the ODU overhead fields and their roles.

Finally, this video discusses special ODUk signals, such as ODU0, ODU2e, and ODUflex.  

Continue reading “Lesson 2 – ODU Framing”