To better understand the available options for data center migration, it is useful to become familiar with the alphabet soup that makes up the suffixes used to distinguish transceiver types. For example, IEEE suffixes used for 10G: 10GBASE-SR, 10GBASE-LR and 10GBASE-ER. SR is always used for multimode and stands for Short Reach (i.e. 400 meters on OM4).LR and ER are used for singlemode, with LR being Long Reach (10 kilometers), and ER being Extended Reach (40 km). Pretty simple so far, right?