Linear Protection Switching

This post briefly defines the term: Linear Protection Switching.

What is Linear Protection Switching?

A Linear Protection-Switching System is a Protection System (or Protection Group) that contains two nodes:

Each of these two nodes is exchanging normal traffic signals, with each other, over a protected network that consists of both the Working Transport entity and the Protect Transport entity.

I show some simple pictures of Linear Protection Switching Systems below in Figures 1, 2, and 3.

The 1+1 Protection-Switching Architecture

1+1 Linear Protection-Switching System

Figure 1, Illustration of a Linear Protection Switching System (A 1+1 Protection-Switching System)

In Figure 1, I show a simple illustration of a 1+1 Protection-Switching system, which also presents the bidirectional flow of traffic between the Head-End and Tail-End Nodes.

If you would like to learn more about the 1+1 Protection-Switching Architecture, then check out the post on this topic.

The 1:N Protection-Switching Architecture

Linear Protection Switching - 1:2 Protection Switching Architecture

Figure 2, Illustration of a Linear Protection Switching System (A 1:2 Protection-Switching System) – for the East to West Direction

Linear Protection Switching - 1:2 Protection-Switching Architecture

Figure 3, Illustration of a Linear Protection Switching System (A 1:2 Protection-Switching System) – for the West to East Direction

Figures 2 and 3 each present an illustration of a 1:2 (or 1:N) Protection-Switching System.

Please note that the 1:N Protection-Switching Architecture figures are more complicated than that for the 1+1 Protection-Switching Architecture.

Therefore, I needed to show this architecture in the form of two figures. 

One figure that shows the traffic flowing from West to East, and the other figure that illustrates the traffic flowing from East to West.

If you would like to learn more about the 1:2 (or 1:N) Protection-Switching architecture, then check out the post on that topic.

In summary, both the 1+1 and the 1:N Protection-Switching schemes are Linear-Protection Protection-Switching systems.

Design Variations for Linear Protection-Switching Systems

Linear  Protection-Switching systems are available in a wide variety of features.  I’ve listed some of these features, and their variations below.


Switching Type

Operation Type

APS Protocol – Using the APS/PCC Channel

  • No Protocol, or
  • Uses the APS Protocol (per ITU-T G.873.1 – for OTN Applications)

Click on any of the links above to learn more about these design variations within a Linear Protection-Switching System.

What about Other Protection-Switching Architectures?

There are other types of Protection Switching System, which are not Linear, such as Shared-Ring Protection-Switching or Shared-Mesh Protection-Switching.

Please see the relevant posts for more information about those types of Protection-Switching Systems.

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