SPECIAL CIRCUMSTANCES SERIES: FluxLight 10GBASE-LRM Optical Transceiver Application

10GBASE-LRM over existing FDDI Fiber


So here is the situation, you have an existing switch in your main campus data center that is bursting at the seams. You only have a small budget and not a lot of time to get a bunch of 1G optical connections deployed a few floors up.  A maintenance guy who has worked there forever tells you there is some old multimode fiber they deployed for 100Mbps transmission back in the 80’s running up to the floor in question…and it is not in use. You are in luck! No so fast. It turns out that is the old orange-jacketed FDDI grade fiber, not the new laser-optimized OM3 fibers in the aqua jacket. You check out the 10GBASE-SR specifications and find its good for a lousy 26 meters on this old fiber. The link you are trying to push is more like 126 meters. What are you going to do?

You do some more investigating and find there is another transceiver type, costs a few bucks more but sounds like it will do the job. It is called a 10GBASE-LRM, LRM meaning Long Range Multimode. This module, deployed along with the use of mode-conditioning fiber jumpers, is designed for up to 220 meters over 62.5 micron core FDDI grade fiber. The key bit of technology to make this possible is called Electronic Dispersion Compensation (EDC). The EDC circuitry in the receiver of the LRM transceivers compensates for the optical signal degradation caused by modal dispersion.

For illustrative purposes two different brands of Ethernet switches are used in this example, an existing Cisco switch down in the data center and a new Meraki device to be deployed upstairs. The main data center switch is the Cisco Catalyst 3850-24XS. The new Meraki is model number is MS410-16. All that is necessary beyond those switches are the 10GBASE-LRM optical transceivers and the mode-conditioning patch cables.

MAIN SWITCH: Cisco Catalyst 3850-24XS

Cisco Catalyst 3850-24XS

Cisco’s 3850 series is comprised of more than 30 different models. Most models are fixed configuration but some accept a range of plugins, typically to add a variety of high-speed (10G and 40G) interfaces. The 3850-24XS includes 24 SFP+ ports capable of running at 1G or 10G. Addition uplinks can be added using a 4x or 8x 10G module or a 2 x 40G QSFP+ module.

The Catalyst 3850 supports a range of AOC (Active Optical Cable) and DAC (Direct Attached Copper) interconnect cables lengths as well as following 10G SFP+ transceiver options.

Table 1 SFP+ Optical Transceivers

SFP-10G-SR SFP+ SR, 300m/OM3, 400m/OM4, duplex LC
SFP-10G-LR SFP+ LR, 10km, SMF, duplex LC
SFP-10G-LRM SFP+ LRM, 220 OM1 MMF, duplex LC
SFP-10G-ER  SFP+ ER, 40km, SMF, duplex LC
SFP-10G-ZR SFP+ ZR, 80km, SMF, duplex LC
SFP-10G-T SFP+ T, 30m, CAT7, RJ45
SFP-10GBX-UD-PAIR SFP+ BX, 10km, SMF, simplex LC


SFP+ BX, 40km, SMF, simplex LC


REMOTE SWITCH: Cisco Meraki MS410-16

Cisco Meraki MS410-16

As stated earlier, this application is on a tight budget. Therefore, a switch from Cisco’s Meraki MS series has been selected fort the remote site.

The Meraki line is designed to minimize both capital outlays and the time required to operate and maintain the units. It utilizes and intuitive cloud-based user interface, allowing operators to quickly get the devices up and running. Maintenance and debugging activities are also great streamlined but getting away from the tedious Command Line Interface (CLI) that is often required with other switches.

The MS410-16 is primarily designed for aggregation of multiple 1G fiber links into its dual 10GbE SFP+ uplinks. It includes 16 SFP 1GbE slots and 2 SFP+ 10G slots. Supported 1G SFP and 10G SFP+ modules are listed below.

Table 2 SFP+ 10G Optical Transceivers

MA-SFP-10G-SR SFP+ SR, 300m/OM3, 400m/OM4, duplex LC
MA-SFP-10G-LR SFP+ LR, 10km, SMF, duplex LC
MA-SFP-10G-LRM SFP+ LRM, 220 OM1 MMF, duplex LC


Table 3 SFP+ 1G Optical Transceivers

MA-SFP-1GB-SX SFP SX, 550m/OM2, 300m/OM1, duplex LC
MA-SFP-1GB-LX10 SFP LX, 10km, SMF, duplex LC




FluxLight Cisco-compatible SFP-10G-LRM

FluxLight Cisco-compatible SFP-10G-LRM

FluxLight’s SFP-10G-LRM is a Cisco® compatible 10GBASE-LRM SFP+ Optical Transceiver and is factory pre-programmed with all the necessary configuration data for seamless Cisco network equipment integration. These transceivers perform identically to Cisco® original transceivers, are 100% compatible and support full hot swapping operation. The SFP-10G-LRM is 100% SFP+ MSA (Multi-Source Agreement) compliant.

FluxLight Meraki compatible MA-SFP-10G-LRM

FluxLight Meraki-compatible MA-SFP-10G-LRM

The MA-SFP-10G-LRM SFP+ optical transceiver from FluxLight is 100% equivalent to the Cisco-Meraki transceiver of the same part number. It is fully compatible with the Meraki 410 switch described in this note. Like all FluxLight optical transceivers, both the SFP-10G-LRM and the MA-SFP-10G-LRM are backed by FluxLight’s limited lifetime warranty.


A mode-conditioning patch cable adapts single-mode launched signal to a multi-mode fiber. It does this by using a centerline offset splice on the transmit side. This is a the single-mode to multi-mode transmission direction. No special adaptation is required in the other direction.

The picture below shows a typical mode-conditioning fiber jumper. The centerline offset splice ins in the black tube seen in the middle of the jumper.

mode-conditioning fiber jumper


Installation of this configuration involves plugging two 10GBASE-LRM optical transceivers into each of the switches. The MA-SFP-10G-LRM into the Meraki MS410 and the SFP-10G-LRM into the Cisco 3850.  Next, a mode conditioning patch cable is used on the transmit side of each LRM transceiver to adapt the single-mode launch to the existing multi-mode trunk fiber. Finally, the mode-conditioning jumper is connected to the existing FDDI-grade fiber. This completes the connection.

10GBASE-LRM Application over existing FDDI Fiber

This note demonstrated the use of the 10GBASE-LRM on Cisco and Meraki equipment. FluxLight offers 10GBASE-LRM transceivers for many other vendors as you can see listed on this webpage. FluxLight is continually expanding its compatibility list so, if you don’t see an OEM listed for which you would like compatibility, please contact us at: 888-874-7574 or quotes@FluxLight.com


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