OTN – Lesson 10 – Video 1M – Entire Source Direction Path – All Atomic Functions (ODU Multiplexed Applications)

This post presents the 1st of the 6 Videos that covers training on the Peformance Monitoring of the ODUk Layer (for Multiplexed Applications). This post focuses on the Source Direction ODU-Layer Atomic Functions.

OTN – Lesson 10 – Video 1 – The Entire Source Direction Path – All Atomic Functions (ODU Multiplexed Applications)

Check Out the Video Below

Click HERE to Go to Video 2 – The OTUk/ODUk_A_Sk and ODUk_TT_Sk Atomic Functions
Click HERE to return to the Main Lesson 10 Page – Multiplexed Applications

What We Cover in this Video

Video 1 (of the Multiplexed ODu4 System Videos) covers the following topics.

  • A brief review of Multiplexed Applications:
    • The PT = 0x20 Approach, and
    • The PT = 0x21 Approach
  • A brief review of the ITU-T G.798 Atomic Function’s support of the Multiplexed Applications
    • The ODUkP/ODU[i]j_A_So/Sk Functions (for PT = 0x20 Applications), and
    • The ODUkP/ODUj-21_A_So/Sk Functions (for PT = 0x21 Applications)
  • Our Application Example: 80 Channels of 1000BASEX -> ODU0 -> ODU4
  • ODU0P/CBR_ETC1000X-A_So (1Gbps Ethernet Adaptation Source Function)
  • Main Purpose: To take a 1000BASE-X (1Gbps Ethernet signal) and map this signal into an ODU0 signal using the GMP-TTT Mapping Procedure.
    • Generates a Default PMOH within the outbound ODU0 signal.
    • Sends the ODU0 signal towards the downstream ODU0_TT_So function for further processing
    • On-Board Clock Generator
      • Synthesizes a 1.244160 GHz Clock signal (e.g., the ODU0 bit-rates per ITU-T G.709) along with the AI_CK, AI_FS, and AI_MFS output signals to create an ODU0 signal.
    • ODU0 Overhead Settings
      • PT (Payload Type) within the PSI Message – set to 0x07 for 1000BASE-X mapped into an ODU0.
      • CI_SSF -> CSF bit-field within the outbound PSI Message (of OPU0 Frame)
  • ODU0_TT_So Function
  • Main Purpose: To compute a Real (and Correct) PMOH and insert data into its ODU0 data-stream.
    • The role of this function is very similar to what we described back in the discussion of the ODUk_TT_So function (in the Non-Multiplexed Portion of Lesson 10).
  • ODUkP/ODUj-21_A_So Function (ODUk to ODUj Multiplex Source Function)
  • Main Purpose: In this example, the ODUkP/ODUj-21_A_So function will map and multiplex 80 ODU0 signals into an OPU4/ODU4 server signal.
    • Convert each ODUj tributary signal into an Extended ODUj signal by attaching the FAS and MFAS fields to each ODUj frame.
    • APS Support
      • Within the ODUj Tributary Signal itself, and
      • Within the ODUk Server Signal
    • Can configure each ODUj tributary to operate in the Locked Mode (e.g., it overwrites the ODUj tributary signal with the ODUj-LCK Maintenance signal and maps/multiplexes that signal into the ODUk server signal.
    • Setting the PT byte (within the outbound ODUk server signal to 0x21).
    • Quick Review of the MSI bytes (within each outbound PSI Message).
    • The OMFI Byte-field (for ODU4 Multiplexed Applications ONLY).
    • We set the PMOH within the ODUk Server Signal to the Default Values. Route this signal to the downstream ODUk_TT_So Function.
  • ODUk_TT_So Function
  • Main Purpose: To compute a Real (and Correct) PMOH and insert data into its ODU4 data stream.
    • The role of this function is the same as what we described back in the discussion of the ODUk_TT_So function (in the Non-Multiplexed Portion of Lesson 10).
  • OTUk/ODUk_A_So Function
  • Main Purpose: To map an ODU4 client signal into the OTU4 Server signal.
    • The role of this function is the same as what we described back in the discussion of the ODUk_TT_So function (in the Non-Multiplexed Portion of Lesson 10).

In Figure 1, I highlight the Atomic Functions discussed in Video 1.

ODU4/OTU4 Multiplexed System with the Source Direction Atomic Functions Highlighted

Figure 1, Illustration of the ODU4/OTU4 System, with the Atomic Functions that we discuss in Video 2 highlighted

You Can Also Check Out the Video Below:

Click HERE to Go to Video 2 – The OTUk/ODUk_A_Sk and ODUk_TT_Sk Atomic Functions

Click HERE to return to the Main Lesson 10 Page – Multiplexed Applications

Resources, Corrections, and Additional Information about this Post

Resources Page - Lesson 10 - ODU Layer Defect Handling and Performance Monitoring Requirements

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Mistakes and Corrections to OTN Lesson 10 - ODU Layer Defects and Performance Monitoring Requirements

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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 2N – The ODUk_TT_So and OTUk/ODUk_A_So Atomic Functions

This post presents the 2nd of the 7 Videos that covers training on the Peformance Monitoring of the ODUk Layer (for Non-Multiplexed Applications). This post focuses on the ODUk_TT_So and OTUk/ODUk_A_So Atomic Functions within the Source Direction ODU-Layer.

OTN – Lesson 10 – Video 2N – The ODUk_TT_So and OTUk/ODUk_A_So Atomic Functions

This blog post contains a video that describes the following two Atomic Functions in detail.

  • The ODUk_TT_So Atomic Function, and
  • The OTUk/ODUk_A_So Atomic Function.  

Continue reading “OTN – Lesson 10 – Video 2N – The ODUk_TT_So and OTUk/ODUk_A_So 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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