Jeff_k_M 5/6/2013 | 11:44:03 PM
re: Arista's On-Board Optics Boost 100G Density It could be true that no one has officially passed Telcordia, but this is what I was eluding to in my first post. If you use these in a decent environment and don't mechanically stress them too much, they perform quite well. They're raw optical performance isn't far different than that of a single fiber connector, but yes when you stress them they don't perform as well. There's has to be some trade-off when you cram many fibers in just about the same space, as a single fiber connector. A big part of the problem with these connectors is that, even after all the years they've been around, still so many people do not understand how to polish them correctly and perhaps just as important, clean them properly after polishing.
Jeff_k_M 5/6/2013 | 11:39:43 PM
re: Arista's On-Board Optics Boost 100G Density In GR-1435, for media type 2 proof testing you bend the fiber perpendicular to the connector, but in the same plane. Meaning you only bend the ribbon the way it was designed to be bent. So it won't matter if it's too stiff in the one direction. What is all this about only using the middle 8? I have made, tested, and used at least a thousand 12 fiber MTPs, with all 12 fibers in the ferrule. I didn't see any issue? Is this an OSP thing?
redface 5/4/2013 | 6:20:46 AM
re: Arista's On-Board Optics Boost 100G Density MT connectors have been a necessary evil. They have the form factor required, but the performance is far inferior to that of single channel connectors. I think MT connectors have never passed the Telcordia reliability tests. This is the reason that MT connectors are not as widely deployed as their functionality would suggest.

Even the ribbon fibers are problematic. Which is why you only use the inner 8 fibers of a 12 fiber ribbon. The ribbons are too stiff in one direction...
cw.774 5/3/2013 | 10:02:12 PM
re: Arista's On-Board Optics Boost 100G Density yes - It is the 8 inner fiber positions. This avoids the problems with using the end positions. I wonder why you think it's a reliability concern?

My understanding has been for the last 10 years that MT should not be a reliability risk here. It is a stable technology proven for single mode applications so these multimode applications shouldn't be a risk. It's little brother (mini MT) is a problem however and proved useless for single mode fiber,
highfiber 5/2/2013 | 7:36:38 PM
re: Arista's On-Board Optics Boost 100G Density If people would accept the fact that you must clean fiber end faces before plugging them in, there would be a lot less unreliability. The fact that you don't clean 12 fibers at a time in an MTP just means you have a higher probability of an issue with the whole MTP interface then when you are only not cleaning two fibers in an LC connector.
Jeff_k_M 5/2/2013 | 2:21:19 AM
re: Arista's On-Board Optics Boost 100G Density Short of being used in an OSP environment there is nothing terrible about an MTPs reliability. Assuming you can withstand the slightly higher IL in your budget, things should be fine.
redface 5/2/2013 | 12:48:41 AM
re: Arista's On-Board Optics Boost 100G Density Might be a little more complicated than you think

For VCSELs, there is no wavelength combining. Each 12Gb/s resides in a separate fiber. So probably each 100G port uses one 12 channel MTP array connector (the outermost fibers are probably unused). For a card with 12 ports, 12 MTP connectors will have to be used. However, MTP connectors have far inferior reliability compared to single channel connectors. I think there might not be insignificant problems with the Arista design.
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