Cisco SFPs

Hello all,

I have recently been given full responsibility over the Network while only having 2 years of limited networking experience. I am tackling this in learning chunks, and I'm now on SFP. My question is about Cisco SFPs, and when/how to use them correctly. I have noticed different SFPs being used in my environment despite each switch being virtually the same. We have... *GLC-SX-mm-RGD *GLC-SX-MMD *GLC-SX-MM *SFP-10G-SR-S (used for 10gb uplinks, I think?)

I am confused because I was told (before the main Network Admin left) that we had NO SFPs and needed to order more. However, I am sitting here with 15 SFPs in front of me. I am under the assumption that GLC-SX-MM-RGD and GLC-SX-MMD are the same except for one being rugged and the other not. I am using Cisco Catalyst 2960-X Series Switches if that helps.

Please correct me on where I am wrong, I wish to learn. If this is too green of a question, let me know and I will delete my post.

Thank you for any help!