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 ?
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)
Regards
Faisal Imtiaz
Snappy Internet & Telecom
7266 SW 48 Street
Miami, FL 33155
Tel: 305 663 5518 x 232
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.
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 ?
Is it true that if the rx power is higher than (x?) then it shortens the
life of the optics ?
Yes, but thats only true about single mode frequencies not multimode (MM)
because those are not as powerful. All MM is expected to go a very limited
distance, so levels are never high. We have MM 3 foot jumpers between gear
running for years.
You don't need to worry about power range when connecting SR or LR.
However, an ER or ZR on a loopback can damage Rx. The strength of the
receiving signal is always under the tolerance allowed. The 850nm Light is
attenuated very quickly because of the MMF and the 850nm light source. This
light source is more like an LED than a Laser. The MTTF on any transceiver
is 50,000 hours at room temperature. A bigger factor is high temperature,
because the chip is a semiconductor.
Usually on Multi-mode and Low-power single-mode optics the MaxOutputOpticalPower is less than or equal to the MaxInputOpticalPower, so it's not necessary to attenuate. The trade-off is optimized optics versus having an attenuator sticking out the front of the electronics.
Something along the lines of -9.5 to -4 transmit power and -18 to 0 on the Receive power. Multi-Mode optics tend to be more application specific than single-mode A good rule of thumb is keep a minimum of 4dB off the bottom plus 20% of the optical budget, discounting any specific application the above optic would be optimal around -10dB.
Daniel Jameson
Manager - IP Network Engineering
TDS Telecom