10 Meg Ethernet

100 Meg

FDDI:

RJ45 to SFP

CFP: The original 100GbE form factor, very large in size. Legacy at this point.	CFP2: The first attempt to shrink a CFP optic to a more manageable size. Still used for long-haul or DWDM 100GbE optics.
CXP: an early multimode or direct attach copper form factor. Still used occasionally in current production equipment.	CPAK (Cisco proprietary): With the CFP2 form factor still too large, Cisco came out with their proprietary CPAK form factor to provide a smaller optic option. Still used by Cisco in their router lines and Nexus 7000/7700 linecards.
MXP (Arista proprietary): Arista, in a similar position to Cisco, went with a proprietary fixed optic technology vs. a pluggable. MXP ports are 10/40/100GbE compatible. MXP ports can actually light up all 24 strands in the MPO cable, allowing for operation in 12x10GbE, 3x40GbE, or 1x100GbE mode. Arista still offers MXP port switches, but all new models use QSFP28 optics instead.	QSFP28: The QSFP28 optic is the most recent form factor for 100GbE. Unlike the other form factors above which use 10x 10Gbps lanes, the QSFP28 uses 4x 25Gbps lanes, which makes for a much less complex (and hence smaller) optic. The QSFP28 is the same design as the original QSFP, just with faster lanes, so availability and cost reduction have come at a rapid pace with this form factor. Additionally, because of this similarity, QSFP28 ports on switches support 40 and 100GbE modes for easy backwards compatibility.