OTN – Lesson 12 – APS Features within Atomic Functions – Part 1

This blog post presents a video that discusses the APS features within some of the Atomic Functions that we discussed in Lessons 9 and 10.

Lesson 12 – Video 12 – Detailed Implementation of APS within the Atomic Functions – Video 1

This blog post starts our discussion of the APS Features within various Atomic Functions. In this case, we will present how to implement Automatic Protection Switching in great detail. In particular, we will describe the following:

  • APS Features within the OTUk/ODUk_A_So and OTUk/ODUk_A_Sk functions (OTU-Layer/SNC/I Monitoring)
    • How do we implement the APS features within these Atomic Functions to support OTU-Layered SNC/I Monitoring and Protection-Switching?
    • How do we implement a complete System-Level design (using these atomic functions along with the OTUk_TT_So and OTUk_TT_Sk Atomic Functions)?
      • NOTE: We discussed these atomic functions in Lesson 9. However, we did not discuss the APS features (within those functions) then.
  • APS Features within the ODUkP/ODUj-21_A_So and ODUkP/ODUj-21_A_Sk functions (ODU-Layer/SNC/I Monitoring)
    • How do we implement the APS features within these Atomic Functions to support ODU-Layered SNC/I Monitoring and Protection-Switching?
    • How do we implement a complete System-Level design (using these atomic functions along with the ODUk_TT_So and ODUk_TT_Sk Atomic Functions)?
      • NOTE: We discussed these atomic functions in Lesson 10. However, we did not discuss the APS features (within those functions) then.
  • APS Features of the ODUkP/ODUj-21_A_So and ODUkP/ODUj-21_A_Sk functions (CL-SNCG/I Monitoring)
  • How do we implement the APS features within these Atomic Functions to support CL-SNCG/I Monitoring and Protection-Switching?
  • How do we implement a complete System-Level design (using these atomic functions along with the ODUk_TT_So and ODUk_TT_Sk Atomic Functions)?
    • NOTE: We discussed these atomic functions in Lesson 10. However, we did not discuss the APS features (within those functions) then.

Check Out the Video Below

Continue reading “OTN – Lesson 12 – APS Features within Atomic Functions – Part 1”

OTN – Lesson 10 – Video 2M – The OTUk/ODUk_A_Sk and ODUk_TT_Sk Atomic Functions

This post presents the 2nd of the 6 Videos that covers training on the Peformance Monitoring of the ODUk Layer (for Multiplexed Applications). This post focuses on the Sink Direction ODU-Layer Atomic Functions.

OTN – Lesson 10 – Video 2M – The OTUk/ODUk_A_Sk and ODUk_TT_Sk Atomic Functions

This blog post includes a video that begins our discussion of the Sink (or Receive) Direction Atomic Function/Circuitry for the ODU-Layer/Multiplexed Applications.  

In particular, this video reviews the following Atomic Functions

  • OTUk/ODUk_A_Sk Function
  • ODUk_TT_Sk Function

NOTE:  Even though we did review these functions back in the Non-Multiplexed portion of Lesson 10 Training, I wanted to review the Consequent Equations for these functions (once again) because these equations do impact the signals that the ODUkP/ODUj-21_A_Sk function (downstream) will “see.”

Continue reading “OTN – Lesson 10 – Video 2M – The OTUk/ODUk_A_Sk and ODUk_TT_Sk Atomic Functions”

OTN – Lesson 10 – Video 6N – Round-Trip Path Delay Measurements, pN_Delay

This post presents the 6th 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. More specifically, this post presents a video that describes how we can use the ODUk_TT_So and ODUk_TT_Sk atomic functions to measure the pN_Delay parameter.

OTN – Lesson 10 – Video 6N – pN_Delay Measurements (via the ODUk_TT_Sk and ODUk_TT_So Atomic Functions)

This blog post includes a video that discusses how we perform round-trip path delay measurements, pN_Delay, (using two sets of ODUk_TT_Sk and ODUk_TT_So functions) by manipulating the DMp bit-field within each ODUk frame.  

This video also closes out our discussion of the ODUk_TT_Sk Atomic Function.  

Continue reading “OTN – Lesson 10 – Video 6N – Round-Trip Path Delay Measurements, pN_Delay”

OTN – Lesson 10 – Video 5N – ODUk_TT_Sk Atomic Function

This post presents the 5th 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. More specifically, this post presents a video that discusses how the ODUk_TT_Sk Atomic Function declares and clears the PM-dDEG defect condition.

OTN – Lesson 10 – Video 5N – The ODUk_TT_Sk Atomic Function

This blog post presents a video that continues our discussion of the ODUk_TT_Sk Atomic Function.  

This video covers the following features within the ODUk_TT_Sk Atomic Function.

  • How the ODUk_TT_Sk function declares and clears the dDEG (Path Signal Degrade) defect condition?
  • What does the ODUk_TT_Sk function do with its AI_TSF Output pin whenever it declares a Service-Affecting defect condition?
  • What does the ODUk_TT_Sk function do with its AI_TSD Output pin whenever it declares the dDEG (Signal Degrade) defect condition?  
  • Defect Correlation Equation Analysis
  • Consequent Equation Analysis 
  • Performance Monitoring Equation Analysis

Continue reading “OTN – Lesson 10 – Video 5N – ODUk_TT_Sk Atomic Function”

OTN – Lesson 10 – Video 4N – More of the ODUk_TT_Sk Atomic Function

This post presents the 4th 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. More specifically, this post includes a video that describes how the ODUk_TT_Sk Atomic Function declares and clears the dTIM, ODUk-AIS, dLCK and dOCI defect conditions.

OTN – Lesson 10 – Video 4N – More of the ODUk_TT_Sk Atomic Function

This blog post includes a video that continues to describe the role/functionality of the ODUk_TT_Sk atomic function

In particular, this video explains how the ODUk_TT_Sk function declares and clears the following defect conditions.  

  • dTIM – Trail Trace Identifier Mismatch defect
  • dAIS – ODUk-AIS defect condition
  • dLCK- ODUk-LCK defect condition
  • dOCI – ODUk-OCI defect condition

Continue reading “OTN – Lesson 10 – Video 4N – More of the ODUk_TT_Sk Atomic Function”

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”

What is an Atomic Function for OTN?

This post briefly introduces the concept of the Atomic Functions that ITU-T G.798 uses to specify the Performance Requirements of OTN systems.


What is an Atomic Function for OTN Applications?

If you have read through many of the ITU standards, particularly those documents that discuss the declaration and clearance of defect conditions, you have come across Atomic Functions.

For OTN applications, ITU-T G.798 is the primary standard that defines and describes defect conditions.

If you want to be able to read through ITU-T G.798 and have any chance of understanding that standard, then you will need to understand what these atomic functions are.

I will tell you that you will have a tough time understanding ITU-T G.798 without understanding these atomic functions.

Therefore, to assist you with this, I will dedicate numerous blog postings to explain and define many of these atomic functions for you.

NOTE:  I also cover these Atomic Functions extensively in Lesson 8 within THE BEST DARN OTN TRAINING PRESENTATION…PERIOD!!!

OK, So What are these Atomic Functions?

You can think of these atomic functions as blocks of circuitry that do certain things, like pass traffic, compute and insert overhead fields, check for, and declare or clear defects, etc.

These atomic functions are theoretical electrical or optical circuits.  They have their own I/O, and ITU specifies each function’s functional architecture and behavior.

It is indeed possible that a Semiconductor Chip Vendor or System Manufacturer could make products that exactly match ITU’s descriptions for these atomic functions.  However, no Semiconductor Chip Vendor nor System Manufacturer does this.  Nor does ITU require this.

ITU has defined these Atomic Functions such that anyone can judiciously connect a number of them to create an Optical Network Product, such as an OTN Framer or Transceiver.

However, if you were to go onto Google and search for any (for example) OTUk_TT_Sk chips or systems on the marketplace, you will not find any.  But that’s fine.  ITU does not require that people designing and manufacturing OTN Equipment make chips with these same names nor have the same I/O as these Atomic Functions.

OK, So Why bother with these Atomic Functions?

The System Designer is not required to design a (for example) OTUk_TT_Sk function chip.  They are NOT required to develop chips with the same I/O (for Traffic Data, System Management, etc.).

However, if you were to design and build networking equipment that handles OTN traffic, you are required to perform the functions that ITU specified for these atomic functions.

For example, if you design a line card that receives an OTUk signal and performs the following functions on this signal.

  • Checks for defects and declare and clear them as appropriate, and
  • Monitors the OTUk signal for bit errors and
  • Converts this OTUk signal into an ODUk signal for further processing

Although you are NOT required to have OTUk_TT_Sk and OTUk/ODUk_A_Sk atomic function chips sitting on your line card, you are required to support all of the ITU functionality defined for those functional blocks.

Therefore, you must understand the following:

  1. Which atomic functions apply to your system (or chip) design, and
  2. What are the requirements associated with each of these applicable atomic functions?

If you understand both of these items, you fully understand the Performance Monitoring requirements for your OTN system or chip.

What type of Atomic Functions does ITU-T G.798 define?

ITU-T G.798 defines two basic types of Atomic Functions:

  • Adaptation Functions and
  • Trail Termination Functions

I will briefly describe each of these types of Atomic Functions below.

Adaptation Functions

Adaptation Functions are responsible for terminating a signal at a particular OTN or network layer and then converting that signal into another OTN or network layer.

For example, an Adaptation function that we discuss in another post is a function that converts an ODUk signal into an OTUk signal (e.g., the OTUk/ODUk_A_So function).

Whenever you read about atomic functions (in ITU-T G.798), you can also tell that you are dealing with an Adaptation atomic function if you see the upper-case letter A within its name.

For example, I have listed some Adaptation functions that we will discuss within this blog below.

  • OTSi/OTUk-a_A_So – The OTSi to OTUk Adaptation Source Function with FEC (for OTU1 and OTU2 Applications)
  • OTSi/OTUk-a_A_Sk – The OTSi to OTUk Adaptation Sink Function with FEC (for OTU1 and OTU2 Applications)
  • OTSiG/OTUk-a_A_So – The OTSiG to OTUk Adaptation Source Function with FEC (for OTU3 and OTU4 Applications)
  • OTSiG/OTUk-a_A_Sk – The OTSiG to OTUk Adaptation Source Function with FEC (for OTU3 and OTU4 Applications)
  • OTUk/ODUk_A_So – The OTUk to ODUk Adaptation Source Function
  • OTUk/ODUk_A_Sk – The OTUk to ODUk Adaptation Sink Function
  • ODUkP/ODUj-21_A_So – The ODUkP to ODUj Multiplexer Source Atomic Function
  • ODUkP/ODUj-21_A_Sk – The ODUkP to ODUj Multiplexer Sink Atomic Function

Another Way to Identify an Adaptation Function?

ITU in general (and indeed in ITU-T G.798) will identify the Adaptation Function with trapezoidal-shaped blocks, as shown below in Figure 1.

OTUk/ODUk_A_Sk Function - Adaptation Atomic Function

Figure 1, A Simple Illustration of an Adaptation Function (per ITU-T G.798)

Now that we’ve briefly introduced you to Adaptation Functions let’s move on to Trail Termination Functions.

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Trail-Termination Functions

Trail Termination functions are typically responsible for monitoring the quality of a signal as it travels from one reference point (where something called the Trail Termination Source function resides) to another reference point (where another thing is called the Trail Termination Sink function lies).

When you read about atomic functions (in ITU-T G.798), you can also tell that you are dealing with a Trail Termination atomic function if you see the upper-case letters TT within its name.

The Trail Termination functions allow us to declare/clear defects and flag/count bit errors.

I’ve listed some of the Atomic Trail-Termination Functions we will discuss in this blog below.

  • OTUk_TT_So – The OTUk Trail Termination Source Function
  • OTUk_TT_Sk – The OTUk Trail Termination Sink Function
  • ODUP_TT_So – The ODUk Trail Termination Source Function (Path)
  • ODUP_TT_Sk – The ODUk Trail Termination Sink Function (Path)
  • ODUT_TT_So – The ODUk Trail Termination Source Function (TCM)
  • ODUT_TT_Sk – The ODUk Trail Termination Sink Function (TCM)

Another way to Identify a Trail-Termination Function?

In general (and indeed in ITU-T G.798), ITU will identify Trail Termination Function with triangular-shaped blocks.  I show an example of a drawing with a Trail-Termination below in Figure 2.

OTUk_TT_Sk Function - Trail Trace Atomic Function

Figure 2, A Simple Illustration of a Trail Termination Function (per ITU-T G.798)

We will discuss these atomic functions in greater detail in other posts.

 

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