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Your LAN network probably has 100 Mb Ethernet copper drops and 1 Gb Ethernet backbones.  That backbone is likely optical over 62.5/125 µm (standard OM1) or 50/125 µm (standard OM2) multimode fibers. These fibers are terminated with SC connectors, ST connectors, or LC connectors if you were a visionary when this infrastructure was first installed. Fiber Optic LAN Connector LC ST SC

Now you are noticing that your bandwidth requirements are approaching 1 Gb at an increasing number of your drops.  You read up on 10 Gb Ethernet (10G, 10 Gb/s or 10 GbE) and notice that 10 Gb Ethernet port costs are approaching those for 1 Gb when you bought them few years ago.  You read the specifications for these transceivers and you begin to realize that your installed optical fiber may not support your migration to 10 Gb Ethernet.   So you are now contemplating a forklift upgrade to 10 Gb/s.  The 10 Gb Ethernet specification (IEEE 802.3ae) using optical cabling recommends OM3 multimode fiber.  OM3 fiber is a 50/125 µm optical fiber that is compliant to EIA/TIA-492AAAC-A, Laser Optimized Multimode Fiber specification (LOMF), and has an Effective Modal Bandwidth (EMB) of 2000 MHz•km at 850 nm.  Premises cabling that contains this fiber is allowed to have the “aqua” colored jacket.  This optical fiber supports 10G transmisison for 300 meters.  You check the market and notice that the biggest bang for your 10 GbE buck is provided by transceivers operating at 850 nm on multimode fibers.  The majority of these transceivers are offered using LC connector ends. So a quick review tells you that 10 Gb Ethernet over multimode is good, over OM3 multimode is better, and using LC ends is best.

MPO Connector close upHowever, you don’t want another cabling upgrade a few years down the road.  So what follows 10 Gb Ethernet?   40/100 Gb Ethernet.  The specification for 40/100 Gb Ethernet is scheduled to be released around June 2010, and the designated multimode fiber to support 40/100G Ethernet will be OM3 at a minimum.    It also details that the multimode connector used is the MPO/ MTP®  style connector.  This connector is usually offered in a 12-fiber per connector style although higher counts are available. (MTP® is the Registered Trademark name for the MPO connector manufactured by USCONEC.)

Now we are getting down to brass tacks.  The most advantageous and economical route to 10 Gb Ethernet uses laser optimized multimode fibers that are terminated with LC ends.  The roadmap then leads to 40/100 Gb Ethernet a few years later.  That requires OM3 multimode fiber with MPO/MTP ends.  While the choice of fiber grade is clear, is there a possible migration path from the LC’s of 10 GbE to the MPO’s of 40/100 GbE?

Fiber Optic LAN Cassette LC MTPThat migration path does exist and is quite popular in data centers or in situations where rapid installation with guaranteed results are mandated.  A modern layout takes advantage of the benefits of using preterminated optical cable assemblies.  The trunk (backbone) cable is terminated with MTP connectors at the main cross connect as well as the horizontal cross connect.  Next, take a 12-fiber or 24-fiber cassette and snap it into a conventional patch panel at each end.  This cassette supports any connector type at the front (user) side.  The back of the cassette accepts one or two MTP connectors from the trunk cable.  This is as simple as it gets for 10 GbE or 1 GbE solutions -- MTP cable assemblies in the backbone with the cassettes handling the conversion to LC or SC connectors.  From there it is just patch cords to the switches, routers, or servers.

Fiber Optic LAN LC MTP HarnessFast forward a few years.  Now you need to upgrade some of your links to support 40 Gb Ethernet.  Your trunk optical cable assemblies are already terminated with MTP connectors. The 40 Gb Ethernet switches and servers use the MTP connector ports, as well.  What you have at your patch panels are those cassettes with MTP’s in the back and LC’s or SC’s up front.  Maximum re-use of what you have would involve replacing those six or twelve conventional 2-fiber patch cords with an optical “harness” that has your connector type on one end and an MTP connector on the other end.  This harness becomes your patch cable and you simply plug in the MTP to your active device to crank up 40/100 Gb Ethernet.

MTP to MTP Adapter PanelWhat do you do if you need the maximum density available to enable 40/100 Gb Ethernet?  Your solution is only a bit different from that detailed previously.  This time, pop out the cassette and replace it with an MTP/MTP adapter panel.  These panels have six, eight or twelve MTP adapters each.  Plug in your trunk cable MTP’s inside the patch panel and use MTP/MTP patch cord in the front to connect to your active devices. 

Let’s summarize.  If you are planning an infrastructure upgrade to support 10 Gb Ethernet now and also ensure support for 40/100 Gb Ethernet in the future, your shopping list is fairly small.  Run optical cables that contain OM3 grade multimode fibers that are preterminated with MTP/MPO connectors.  At the patch panels, plug these trunk cables into cassettes supporting your desired connector in the front.  When 40/100 Gb comes along, replace your existing 2-fiber patch cords to your actives with an optical harness.  If maximum density is mandatory, simply replace your cassettes with MTP/MTP panels and use MTP patchcords to link with your active devices. Maximum reutilization combined with maximum ease.  A winning combination.

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About Berk-Tek, A Nexans Company

About Berk-Tek, A Nexans Company For more than 45 years, Berk-Tek has been a leading manufacturer of more than 100 different network copper and fiber optic cable products. The company has led in the development of high-performance and enhanced fiber optic and UTP cables designed to transport high-speed data and voice transmissions. Berk-Tek has major manufacturing facilities at New Holland, PA, Fuquay-Varina, NC and Elm City, NC. For more information, visit