Pattern FO-B

A C37.94 island inside an E1 or SDH network

Where the clock master sits, and what happens to the protection when it disappears.

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Area: Fiber & OT
Environments: 1
Products used: 2

How it is built

The C37.94 island meets the transport network. The clock master decides what happens when it disappears.

Used in these environments

Power plant with high electromagnetic interferenceImmunity is the requirement, and it is the one figure the datasheet is expected to answer without discussion.

How it works

A C37.94 island meets an E1 or SDH transport network. The converter maps the protection channels into the transport frame, and the transport network carries them alongside everything else.

The clock master decides what happens next

In a synchronous chain one device’s clock is followed by all the others. Two ends on internal clock will slip within minutes. The diagnostic rule is worth memorising: slips at an even interval mean timing, an irregular interval means optics.

What the transport network adds

Delay, and the possibility of asymmetry when it protection-switches. Both belong in the delay budget from the start, and both are outside the control of whoever owns the protection.

In the catalogue