MultiMode Fiber Connectivity... (850nm) Power Question

Wed Feb 11 17:41:23 UTC 2015

On Wed, 11 Feb 2015, Faisal Imtiaz wrote:

> I was looking for feedback on the following question:-
>
> When connecting two MM SFP/SFP+/XFP 's together...(short range).
>
> What should be the best practice receive power range ?

SX (1G) / SR (10G) / SR10 (100G) gear generally has a receive threshold 
that's higher than the maximum launch power.  They are designed for 
short-reach applications (in-building, data center, etc), so no 
attenuation is needed.

> Is it true that if the rx power is higher than (x?) then it shortens 
> the life of the optics ?
> (assumption being made here is that MAX Rx Power is not being exceed as 
> per the spec sheets of the optics)

On short-reach optics, this should never be a problem.  On long-reach 
optics, receiver saturation will generally result in link errors/flaps, 
and possibly high rx power warnings (depending on the gear on the 
receiving end), however, these can be addressed using in-line attenuators.

On very long-reach optics, such as ZX (1G) and ER/ZR (10G), it is possible 
to damage the receivers with too hot of a signal because they are designed 
for long spans and a certain amount of distance-based attenuation is 
factored into the optical power budget.

jms