Compatibility question on fiber modules

[utawakevou]

Recently install 2 Nexus 9000 series with 2 each  QSFP-40G-SR-BD fiber module. We have a stacked 3750 switch which we want to up-link to from the two new nexus. The 3750 got the 1000BaseLX SFP module on it. I use an LC connector fiber patch lead to try and get the connection but it doesn't work so I resort to the base T connection for up-link

I'm sure there must be some incompatibility issue and would appreciate if someone can enlighten me on that.

[Prabath Godevithanage · Accepted solution]

depending on your 9K model you may be able to break out a group your ports to support 1G,see here 

But I cant see anything on the QSFP-40G-SR-BD spec to say that they support 1G,I might just stick with what you did if I have to break out 40 or 10 gig ports

[pwwiddicombe · Accepted solution]

40G-SR sounds like 40 Gig ShortRange (Multimode fiber); and 1000BaseLX is 1 Gig SingleMode fiber; so you have a speed and fiber incompatability here.