The entry of 100G 850 nm VCSELs enables the replacement of copper by multimode fiber in switch-toserver links, and facilitates the upgrade of switch-to-switch links in enterprise networks and data centers. This paper will present the key features and characteristics of multimode VCSELs that enable direct modulation at 100 Gb/s suitable for multimode Ethernet and Fibre Channel standards. Beyond 100G, a bidirectional link using VCSELs of two wavelengths is one potential solution to double the aggregate data rate on duplex fiber links. Elements of both 850 and 910 nm VCSELs that would enable the next generation data links are described.