Bridging the gap
to connect today's IT infrastructure with tomorrow's demands


LC, Ol' Reliable
Upgrading 1/10GbE to 25GbE

Our 1.25 mm ferrule small form factor friend has been utilized in fiber networks for 20+ years. These LC connectors are still popular in data centers today supporting 1GbE to 10GbE IP network connections and thanks to the new SFP28 standard and BiDi Optics, LC will continue to be used for years to come.


















The Small Form-Factor Pluggable 28 (SFP28) is the third generation of the SFP interconnect systems designed for 25G performance defined by IEEE 802.3 25GBASE-SR specifications. Users are now able to use the same LC duplex fiber optic cable for 25GbE providing an excellent migration path for servers encountering port congestion issues including those utilizing virtualization.


At server/switch refreshes, simply swap out the SFP+ pluggables with the new SFP28 pluggables and re-use your existing LC cable plant. Before swapping pluggables confirm your hardware supports SFP28 (anything recent will). Also keep in mind the distance limits for 25GbE when using multimode, 70 meters and 150 meters for OM3 and OM4 respectively.


For many popular ethernet switches available today, BiDi (bi-directional) pluggables are offered which allow you to use LC connectors for your up-links between switches for both 3-tier and Spine & Leaf configurations. 40GbE speeds are supported today, however 100GbE versions are being developed due to the popularity and simplicity of using LC cable plant that may already be in place at your data center. Distance limitations for 40GbE BiDi are reasonable at 100 meters and a light loss budget of 1.5 dB is manageable inside most data centers to remain "within spec".


What about SAN?
LC is still the connector of choice for storage area networks (Fibre Channel) and will continue to be utilized. The latest 16 Gb and 32 Gb speeds still use an LC connector. For link planning, it is best to migrate to OM4 or better when you move from 8 Gb to faster speeds. Of course, stay within the FC limits of 150 meters max and 1.5db budget. Any OM1 or OM2 (orange) fiber cabling still in use in your SAN should be migrated to OM3/OM4 at refresh intervals to make sure you’re able to support current and future FC speeds.


LC is, and will be, relevant
LC connectors will be relevant in fiber optic networks in data centers for the foreseeable future. It’s maturity, small form factor and price point continue to be attractive, especially at the edges of your networks. When deploying any new LC fiber cables be sure to target those with <.15 dB insertion loss to help stay within the light loss budgets of today and tomorrow’s faster speeds.


Upgrading 40GbE to 200GbE


While LC connectors remain popular, as speed demands increase to 100 Gb/s and beyond, newer Quad-SFP connections with MPO/MTP style connectors will be required.


Some background
Beginning with the original Quad Small Form-Factor Pluggable (QSFP) specifications, the foundation was laid to scale up to current 200 Gigabit speeds using QSFP-DD. More about QSFP-DD later. QSFP quickly evolved into the QSFP+ specifications for 4 x 10 Gb/s data rates to support 40GbE and beyond.


QSFP+ has become the standard port type for fiber networks requiring multilane connections. Current Quad-SFP connections utilize an MPO/MTP style connector which has the flexibility of supporting a variety of faster speeds used today and on the roadmap for tomorrow.














Migrating to 200GbE
With these new standards, there’s an easy migration from 40G/QSFP+ to 100G/QSFP28 considering the same MPO/MTP cable can be used. This is now a common approach for future proofing backbone cabling. Optics manufacturers and standards developers are increasingly more aware of the need to utilize existing cable plant whenever possible. In fact, newer versions of QSFP in development will allow the re-use of MPO/MTP cables already in-service making port upgrades easier preserving your investment.


Faster 40G+ speeds are no longer just for your network backbone connections. In fact, many new blade server chassis, which can support a large number of virtual servers, offer QSFP28 pluggables for connecting to the network.


MPO/MTP, the new standard
QSFP ports requiring MPO/MTP cables are quickly becoming the new standard for high-speed networks. Be careful selecting the right MPO for your connection. They can introduce slightly more insertion loss into your overall channel, commonly 0.5 dB. To keep your end-to-end channel loss down (<1.5 dB for some speeds), implementing cables with MTP Elite connectors (<.25 dB for MM, <.35 dB for SM) will help ensure you don’t exceed these limits.















Future-ready Networks
Preparing for tomorrow with forward-looking infrastructures

All roads are leading to 2-fiber (LC) and 8-fiber (MPO/MTP) connections for tomorrow’s data center fiber networks. Excitedly, migration paths do exist that allow for the re-use of cable plant you have in place today! With a careful eye on what hardware may arrive into your data center in the coming year or two, know that the QSFP form factor is quickly being adopted and deployed to support fiber ports in excess of 40GbE. When installing point-to-point home runs or a structured cabling system, be sure to design and implement your fiber network connections to maximize your network infrastructure today while preparing for tomorrow.



                      TOM HODSON, Solution Architect at Total Cable Solutions

                      Questions?  Connect with us at (888) 235-2097.

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