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My primary question is this:

Is it possible to have a simple passive SFP/SFP+ bulkhead passthrough connector, with two female SFP/SFP+ sockets facing opposite directions and wired directly together, for a data cable entering a dust and humidity controlled rack cabinet?

 

However this also stirs up related mysteries:

Are copper SFP/SFP+ cables simply a passive straight-through cable, or are there active electronics involved? If it is passive and straight-through, then:

  • Would it be possible for an SFP/SFP+ fiber module to be joined to a copper SFP/SFP+ cable with a double-ended F/F SFP/SFP+ socket and function properly?

  • And likewise, could two copper SFP/SFP+ cables be joined together with a double-ended F/F SFP/SFP+ socket?

  • Is there such a thing as a copper SFP/SFP+ extension cable, with an SFP/SFP+ socket on one end? If none currently exists, could it work?

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The SFP/SFP+ is placed in active equipment, and it will include a connector for the type of cabling you need (normally, LC connector for fiber, or 8P8C connector for copper). The cable is not SFP/SFP+, that is the electronics for the connection type that is inserted into an SFP/SFP+ slot on the active equipment.

You then use patch cords to connect from the interface on the active equipment to the horizontal cabling. For copper, you use patch panels or punchdown blocks (typically 110) rated for the cable category, where the horizontal cable is terminated on the back side. Fiber will typically have passthrough connectors mounted in a box, where the horizontal cable is terminated on the back side. You simply connect your patch cord (maximum of five meters for copper cabling) to the punchdown block, patch panel, fiber box, etc. to connect to the horizontal cabling. None of these devices use active electronics.

There are various forms of those devices that are rack mountable and can be placed inside an enclosure as you describe.


Copper cabling has a lot of rules around how it can be run and connected, and splices, taps, couplers, etc. are not allowed. On the other hand, fiber is made to be spliced, but there are rules around that, and you must calculate a loss budget and make sure that the splices and connections do not exceed the budget. Once installed, you must run the test suite for the cable type you installed to make sure it passes, and correct the situation if it does not.

Cabling is a huge subject for which there are many books written, and installation experience is required. Most failed cable installations are due to poor installation, which is why you must test after installation.

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Is it possible to have a simple passive SFP/SFP+ bulkhead passthrough connector, with two female SFP/SFP+ sockets facing opposite directions and wired directly together, for a data cable entering a dust and humidity controlled rack cabinet?

First, you have a fundamental misunderstanding. There is no such thing as SFP/SFP+ "sockets" (unless you count the "cages" SFP/SFP+ are inserted into) or cables (excluding "direct-attach" types of SFP/SFP+ like Twinax). SFP/SFP+ are transceivers in a modular form. They are active electronics and do not function without a power source.

The connector type for nearly all SFP/SFP+ transceivers is LC for fiber and 8P8C (commonly referred to as RJ45) for copper solutions. These are what I believe you are actually asking about. As such, it is possible to have a LC/LC or 8P8C/8P8C "passthrough" connector as you describe, but generally speaking this is frowned upon. Throughout the rest of my answer, where you ask about SFP/SFP+ cables/connectors I will answer substituting LC/8P8C in it's place.

Rather, look for a cable penetration solution for the NEMA and/or IEC rating to which you are trying to meet. There are a wide number of solutions on the market that provide for cable penetrations while maintaining these ratings (all the way to fully submersible). Use such a solution when passing cabling into your rack/cabinet.

Are copper SFP/SFP+ cables simply a passive straight-through cable, or are there active electronics involved?

The cables themselves are passive, however the SFP/SFP+ are active (even if they are described as passive, they still require being inserted into a powered device).

Would it be possible for an SFP/SFP+ fiber module to be joined to a copper SFP/SFP+ cable with a double-ended F/F SFP/SFP+ socket and function properly?

No. Put as simply as possible, they speak different "languages." Fiber uses light to pass data and copper uses electric current. There is no way copper and fiber can pass data to each other without some sort of (active) device to bridge the two.

And likewise, could two copper SFP/SFP+ cables be joined together with a double-ended F/F SFP/SFP+ socket?

Again, possible, but likely to violate the standards of proper cabling and could introduce problems to the data communications. Generally speaking, you should be avoiding an splices, couplers, etc. These types of "solutions" may be used in a short term fix, but should be highly avoided for permanent solutions as they may introduce issues that will likely to be difficult to troubleshoot/diagnose later on.

Is there such a thing as a copper SFP/SFP+ extension cable, with an SFP/SFP+ socket on one end? If none currently exists, could it work?

This is really just a form of mechanical splicing. It could work, but again see my answer to your last question.

  • Whatever the specific name, the big square hole on a switch for an SFP module.... is a socket. An SFP fiber module is basically a plug with electronics molded into it. And copper switch-to-switch / SFP to SFP direct attach cables do exist. – Dale Mahalko Oct 3 at 19:36
  • Actually the big square hole on a switch is generally referred to as a "cage" and the connector that is built into the cage is the "socket" where the electrical contacts are made between the SFP and the switch. Feel free to source parts yourself. I do know about direct-attach, which is why my post says "excluding "direct-attach" types of SFP/SFP+ like Twinax". So may I ask what the point of your comment actually is? – YLearn Oct 3 at 20:46

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