04-09-2014 11:05 AM
The sfpShow command will provide power levels for both TX and RX on a particular port. What are typical acceptable level ranges for them? As sfp's and cables age these values change and weak signals may start to cause various error recovery and have been known to cause errors. I am just trying to understand the normal limits. Thanks
04-09-2014 12:42 PM
04-10-2014 12:34 AM
In my experience I consider that a received signal below 100 uW (-10 dBm) is problematic. A higher Rx signal usually does not generate errors, but it is also true that as SFP speeds increase this threshold of mine gotta raise, maybe to 200uW (-7 dBm) in the case of 8G/16G links.
04-21-2014 01:39 PM
TX Power is dependant upon type. A Short Wave will typically transmit in the ~300-400 mWatt range. A Long Wave will be much higher.
RX Power is dependant upon distance. A 30 meter cable should be fairly close to the TX Power. I don't know the formula for drop, but a much longer distance cable will have it. (Best way to see this is to look at a long distance SFP. ~1200 TX Power and ~250 RX Power. Seems off, but distance does affect this)
05-19-2014 08:22 PM
I wrote a short article on this over here > http://erwinvanlonden.net/2012/03/the-importance-of-clean-fibre-optics/
There is a huge difference between te SFP's type especially when you start comparing long-wave ones.
Lookk at the SFP specs over here : http://www.brocade.com/products/all/transceivers/product-details/transceiver-modules/specifications.page