Cisco GLC-SX-MMD 1000BASE-SX SFP Transceiver Module, MMF, 850nm, DOM

[johndnoob]

Network Noob here, I have a question about these.  This is probably a dumb question, but I am not the brightest bulb in the pack.  These GLC-SX-MMD show they are multimode 1000Mbs compatible.  My question is can they operate in 100Mbs mode.  I have found that the 100/1000BASE-LX SFP for long-reach single-mode fibers work for single-mode, but I also saw that SFP Operation at 100M can be achieved by placing a -5dB attenuator on the SFP.  I have been unable to find one, but do they make an attenuator for 1000Mbs multimode SFP?  We have a building with multimode fiber nearly everywhere.  That includes going to the EUDs.  The though is purchase the 1000Mbs SFPs for future use if they change locations or have a life cycle refresh, but the 100 Mbs SFPs are available if there is not a Cisco solution.  I would prefer a Cisco solution as it should be compatible with the Cisco devices we plan to install.

[marce1000 · Accepted solution]

         >...they are multimode 1000Mbs compatible.  My question is can they operate in 100Mbs mode
                             They can't 
         >.... can be achieved by placing a -5dB attenuator on the SFP.
                             Not advisable (if at all possible)

       For all Cisco equipment use this app for compatibility info's : https://tmgmatrix.cisco.com/

 M.

[johndnoob]

I thought as much, but I wanted to verify before I send my thoughts to the customer.  Either they will have to upgrade their internal wiring down the line or purchase new equipment when their life cycle is due.  This is a building that uses MT-RJ fiber connectors and Fiber NICs on their present devices.  100Mbs is what they are going to need.  Thanks for the compatibility tool link.  I needed that.