It’s hard to believe that only four short years ago the data center industry saw the introduction of the QSFP+ 40G BiDi pluggable optical transceiver, which broke the mold by providing 40Gb connectivity over the same fiber format (dual MMF) as 10G SR. Until then, 40G SR4 was the primary option, and required four times more fiber and more expensive optical connectors.
Remember this pair?
The 40G BiDi module enabled data center operators to upgrade from 10G to 40G without changing fiber infrastructure. Since then, Cisco has started shipping dual rate 40G/100G ports on Nexus platforms and 100G QSFP28 pluggable optics to go along with them. And now, to accompany the dual rate switch ports, we’ve introduced a 40G/100G dual rate version of the BiDi as well.
It’s still in a QSFP form factor, but QSFP28 instead of QSFP+. If you’re upgrading one side of the link at a time, you can use this dual-rate optic on the new upgraded end, and still have it talk to the existing 40G BiDi at the other end. Then, when you’re ready to replace the latter with another 40G/100G BiDi, you don’t need to touch the first end. And of course, you don’t need to change the fiber either.