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Connecting MT-RJ and LC uplinks using singlemode fiber


I am looking to Design a network with 3750 as core Switch and 2960 as Edge switch

Core Switch - 3750 24-FS

Edge Switch  2960 24 Base T with 2 SFP

So my question is Can i connect the uplink between core and Edge switch using Single Mode MT-RJ at core end andSingle Mode  LC connector using SFP at Edge end

reason is  i cannot afford 3750 with 12 SFP  at my core end ,which is quite expensive



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Re: Connecting MT-RJ and LC uplinks using singlemode fiber

3750-24FS has 24 ports 100BaseFX.  So I doubt an MTRJ will fit.

100BASE-LX, -BX, -FX SFP-based ports: LC fiber connectors (single/multimode fiber)

Next, for 100BaseFX to work you a GLC-GE-100FX for the 2960 to talk to the 3750.

In both cases, you need LC fibre patch cord to work.

What, by the way, are you trying to achieve?

Re: Connecting MT-RJ and LC uplinks using singlemode fiber


Unfortunately, you cannot directly connect the 3750 24-FX 100BASE-FX ports to the 2960 SFPs over singlemode fiber (SMF).  This is because the 3750 24-FX ports use 50/125- or 62.5/125-micron multimode  fiber-optic (MMF) cabling.

If the distance between the devices does not exceed 6,562 feet/2 kilometers (100FX reach), then you could install a 100Mbps-FX MMF SFP in the 2960 and use MMF cabling between the devices. 

Or, if you only have singlemode fiber available between the two devices, you could install Media Converters between the two devices, such as that from Omnitron Systems.


3750 24-FX 100BASE-FX -----> Multimode Fiber -----> media convertor ----->Singlemode Fiber -----> media convertor* ----->Singlemode Fiber -----> 2960 w/100Base SMF SFP.

* Some media converters can work single-ended, terminating the other end of the link on the switches SFP interface.

Hybrid fiber optic jumper cables are available with different connectors at each end that allow you to transition between connector types (MR-RJ to LC or other).  However, you cannot have a MMF interface at one end of the flink and a SMF interface at the other end (without a conversion device).

Hope this helps!


Community Member

Re: Connecting MT-RJ and LC uplinks using Multimode fiber

Hi Tom,

Thank you very much for your prompt reply, finally i understand.As my cable distance is with in 2Km iam ok with MMF

Secondly i dont't want to use any media convertor in between the Core Switch and Edge Switch

Can i design my uplinks in the following way is it correct? (Using MMF)

CoreSwitch -> MT-RJ---->SC----->[PatchPanne]l------------------------------------------------------------->[PatchPannel]----->SC-----> LC------->[Edge-Switch]

(3750 100Mbps)                      (Near CoreSwitch)                                                               (Near Edge)                                 (2960 100Mbps SFP)

Is 100Mbps SFP  MMF is available for 2960?



Community Member

Re: Connecting MT-RJ and LC uplinks using Multimode fiber

Sorry last Post was bit messy this is my design

[CoreSw]--->MT-RJ--->SC-------->[PatchPannel]---------------------------------------->[Patch Pannel]------------>SC--------->LC----------[Edge Switch]

Re: Connecting MT-RJ and LC uplinks using Multimode fiber


Which exact model number of 2960 switch are you using?  It looks like there are 100Base-Fx SFPs for the 2960, but the following webpage will confirm which 100M SFPs are compatible with your proposed equipment:

Cisco 100-Megabit Ethernet SFP Modules Compatibility Matrix


Shouldn't be a problem connecting with the design you are proposing.  You can buy MT-RJ to SC MMF and SC to LC MMF patch cords at many LAN suppliers, including Anixter.  Just make sure you select the proper fiber type for your patch cords to match the installed fiber (OM-* type...62.5 or 50 micron core size).

Let us know if you have any additional questions.


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