What is a Span within a Shared-Ring Protection-Switching System?
In short, a Span is the set of fiber-optic connections between two adjacent nodes within a Shared-Ring Protection-Switching system.
We further stated that each node (within this Shared-Ring Protection-Switching system) is connected to two neighboring nodes.
A span is a set of fiber-optic media that exists between and connects any two neighboring nodes.
I illustrate a Shared-Ring Protection-Switching system, with the Span (between Nodes B and C) highlighted below in Figure 1.
Figure 1, Illustration of a 4-Fibre/4-Lambda Shared-Ring Protection-Switching system, with the Span (between Nodes B and C) highlighted.
What kind of Signals does a Span Transport?
In most Shared-Ring Protection-Switching systems, a span will consist of two or four fibers transporting the following optical signals.
- Clockwise Direction – Working Transport Entity
- Clockwise Direction – Protection Transport Entity
- Counter-Clockwise Direction – Working Transport Entity
- Counter-Clockwise Direction – Protection Transport Entity
Can a System-Designer implement any sort of Protection-Switching across a Span?
Yes, with a 4-Fibre/4-Lambda Shared-Ring Protection-Switching system, the user can implement Span-Switching as a form of Protection-Switching.
Please see the post on Span-Switching for more information on this topic.