SNCP and MSP: revertive or non revertive?

[Aldbert]

I was wondering which are the pros and cons of choosing revertive vs.
non revertive protections (SNCP and MSP).
One reason for choosing revertive protection I thought of, is that in
case of a unidirectional protection scheme (e. g. both ends switch
independently), in normal conditions, both directions follow the same
path and therefore experience the same delay. Other thoughts?
What do usually Service Providers use in their networks?
Thank you very much.
Aldbert

[Huub van Helvoort]

Hello Aldbert,

You wondered:

> I was wondering which are the pros and cons of choosing revertive vs.
> non revertive protections (SNCP and MSP).

Every switch action causes an interruption of the the signal due to
the difference in propagation delay of the working and protection
path. So in case the transported signal is sensitive to that
non-revertive is used.

> One reason for choosing revertive protection I thought of, is that in
> case of a unidirectional protection scheme (e. g. both ends switch
> independently), in normal conditions, both directions follow the same
> path and therefore experience the same delay.

This is valid if it is important to keep the delay in both
directions (almost) the same.
It would be better to use bi-directional switching in this case
because then the delay in both directions stays the same even
during a protection switch.

> Other thoughts?

See above.

> What do usually Service Providers use in their networks?

In general revertive is provisioned.
The use of non-revertive in ring protection should be avoided
because it affects the sharing of the protection path.

Cheers, Huub.

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