For the past several hours I've been reading documents/PDFs from the last Open Compute Summit and other datacenter/cloud scale collaborative projects...
One of the things we're going to see very soon is fast and cheap SFP28 for 25 gigabit ethernet. White box switch equipment manufacturers in Taiwan and China have taken one quarter of the data lanes used for 100 gigabit ethernet (which is usually implemented with 4 x 25 Gbps serializer/deserializers on the silicon side) and made it work with a 25 Gbps SFP+ form factor. Since it's the same size as a SFP+, possible to build a 48-port x 25 Gbps linecard or switch in a normal rack form factor. Already I'm seeing SFP28 direct attach cables for server-to-switch at $59 each. Breakout direct attach cables that take one QSFP28 100GbE port and turn it into 4 x 25GbE at about $200 each. There are 25Gbps SFP28 1310nm optical, nominally 10km reach optics. http://www.qlogic.com/Resources/Documents/WhitePapers/Adapters/WP_25Gb_Ethernet.pdf http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/datasheet-c78-736950.html
