Alright, I'm hoping that someone can confirm or deny this. In our campus, we have a mix of single mode & multimode fiber cabling between floors & buildings. I have always been an advocate of keeping things simple and the same, but unfortunately the cabling plant pre-dates my time and I can't do anything to fix the situation.
Now this is where the question comes in. Another engineer here ordered several 3750's for a standard lifecycle upgrade. However, when he ordered the SFP's for these switches he ordered all Single Mode, long range fiber. I questioned him about this because we are going to have mismatches between the fiber and the transceivers. This individual is very well respected in our organization and so I have to know my stuff whenever I challenge him on technical issues. He is telling me that Single Mode SFP's will operate just fine when connected to Multimode fiber. This just doesn't seem right to me. I belive the transceivers have major architecture differences and that this simply won't work.
Can anyone confirm for me whether you can use Single Mode SFP's on Multimode fiber?
Single mode and multimode are not interchangable. The main reason is the wave length of the laser and core size of the fiber.
However, there is 1 type of the Cisco GBIC which can support both single mode and multimode fiber. Here is the link for more info, please refer to part number "SFP-GE-L or GLC-LH-SM":