OTN – Lesson 12 – APS Features within Atomic Functions – Part 2

This blog post presents a video that discusses the APS features within some fo the Atomic Functions that we discussed in Lesson 11.

Lesson 12 – Video 13 – Detailed Implementation of APS within the Atomic Functions – Video 2

This blog post continues 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 ODUT/ODU_A_So and ODUT/ODU_A_Sk functions (ODUT/TCM Layer – SNC/S Monitoring)
    • How do we implement the APS features within these Atomic Functions to support TCM Layer i SNC/S Monitoring and Protection-Switching?
    • How do we implement a complete System-Level design (using these atomic functions along with the ODUT_TT_So and ODUT_TT_Sk Atomic Functions)?
      • NOTE: We discussed these atomic functions in Lesson 11. However, we did not discuss the APS features (within those functions) then.

More specifically, we discuss how our system should implement APS and the APS Communication Protocol whenever the upstream ODUT_TT_Sk Atomic Function declares either a Service-Affecting or the TCMi-dDEG defect.

Check Out the Video Below

Continue reading “OTN – Lesson 12 – APS Features within Atomic Functions – Part 2”

OTN – Lesson 11 – Tandem Connection Monitoring Multi-Administration Domain Walk-Thru – Part TWO

This post serves as Part TWO (and the Final Part) for the Multi-Administrative Domain Walk Through and Analysis for our study of Tandem Connection Monitoring.

Lesson 11 – Video 9 – TCM Multi-Administration Domain Walk Through – Part TWO

This blog post contains a video that covers the second (and final) part of the Multi-Administrative Domain Walk-Through.

In particular, this video covers the following topics:

  • Part TWO of our Multi-Administration Domain Walk-Through (using our knowledge of TCM-related atomic functions to analyze this network).

In particular, this post covers the following parts of the Multi-Administration Domain Walk-Through.

  • Initializing the Serving Operating Domain (Operator B) – TCM Level 3
  • Terminating the Serving Operating Domain (Operator B) – TCM Level 3
  • Initalizing the Serving Operating Domain (Operator C) – TCM Level 3
  • Initializing the Protect Domain – TCM Level 4
  • Terminating the Protect Domain – TCM Level 4
  • Terminating the Serving Operating Domain (Operator C) – TCM Level 3
  • Terminating the Leased Service Serving Operator Domain – TCM Level 2
  • Terminating the Service Requesting Domain – TCM Level 1

This video serves as Part TWO (and the Final Part) of our Multi-Administration Domain Walk-Through and Analysis.

Check Out the Video Below.

Continue reading “OTN – Lesson 11 – Tandem Connection Monitoring Multi-Administration Domain Walk-Thru – Part TWO”

OTN – Lesson 11 – Tandem Connection Monitoring Controller and Multi-Administration Domain Walk-Thru – Part ONE

This blog post briefly introduces the Tandem Connection Monitoring Controller Atomic Function. This post also serves as Part ONE for the Multi-Administrative Domain Walk Through and Analysis.

Lesson 11 – Video 8 – TCM Controller and Multi-Administration Domain Walk-Through – Part ONE

This blog post contains a video that covers the first part of the Multi-Administrative Domain Walk-Through.

In particular, this video covers the following topics:

  • An Introduction to the TCM (Tandem Connection Monitoring) Controller Atomic Function
  • An Overview of What We Have Covered thus far – In Lesson 11, and Where We’re Going
  • Introduction to Compound (Atomic Functions)
    • Definition/Introduction to the Source Compound Function
    • Definition/Introduction to the Sink Compound Function
  • Part ONE of our Multi-Administration Domain Walk-Through (using our knowledge of TCM-related atomic functions to analyze this network).

In particular, this post covers the following parts of the Multi-Administration Domain Walk-Through.

  • Initializing the Service Requesting Domain – TCM Level 1
  • How We Initialize the Leased Service Serving Operator Domain – TCM Level 2
  • Initializing the Serving Operating Domain (Operator A) – TCM Level 3
  • Terminating the Serving Operating Domain (Operator A) – TCM Level 3

This video serves as Part ONE of our Multi-Administration Domain Walk-Through and Analysis.

Check Out the Video Below

Continue reading “OTN – Lesson 11 – Tandem Connection Monitoring Controller and Multi-Administration Domain Walk-Thru – Part ONE”

OTN – Lesson 11 – Tandem Connection Monitoring – Sink Atomic Functions – Video 5

This blog post includes a video that discusses both the ODUTm_TT_Sk (Non-Intrusive Monitoring) Function and the ODUT/ODU_A_Sk Atomic Function. This is the last blog post to describe and define the TCM-related Atomic Functions.

Lesson 11 – Video 7 – Tandem Connection Monitoring – ODUTm_TT_Sk and ODUT/ODU_A_Sk Atomic Functions

This blog post contains a video that covers the fifth part of the Sink Direction Tandem Connection Monitoring (TCM) related Atomic Functions.

In particular, this video covers the following two atomic functions:

  • ODUTm_TT_Sk (Atomic Function for Non-Intrusive Monitoring – TCM Applications), and
  • ODUT/ODU_A_Sk

More specifically, this video covers the following aspects of each of these Atomic Functions.

  • ODUTm_TT_Sk Atomic Function
    • Applications in which we would use the ODUTm_TT_Sk Atomic Function (e.g., Non-Intrusive Monitoring for TCM Subnetworks)
    • A brief overview of this function’s capabilities and attributes
    • How this function differs from the ODUT_TT_Sk Atomic Function.
      • When the ODUT_TT_Sk Function is operating in the OPERATIONAL Mode
      • If the ODUT_TT_Sk Function is operating in the MONITOR Mode, and
      • When the ODUT_TT_Sk Function is operating in the TRANSPARENT Mode
  • ODUT/ODU_A_Sk Atomic Function
    • Where this function fits into the Tandem Connection Monitoring Network
    • The Architecture/Functionality of the ODUT/ODU_A_Sk Function
      • Operation in the various TCM Modes (e.g., OPERATIONAL and MONITOR/TRANSPARENT).
      • The Protection Port (for Automatic Protection Switching support).
      • The Removal Block – How this function terminates the “Selected TCMOH and APS/PCC field”.
      • Replacing the Normal ODU signal (carrying client data) with either the ODU-AIS or ODU-LCK Maintenance Signals.
      • Asserting CI_SSF and CI_SSD in response to upstream defect conditions.

This video completes our discussion/review of the TCM-related Atomic Functions.

Check Out the Video Below.

Continue reading “OTN – Lesson 11 – Tandem Connection Monitoring – Sink Atomic Functions – Video 5”

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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