Current duplex connectors do not support 4 duplex connectors in a single QSFP-DD package and 2 duplex connectors in a single SFP-DD package. A smaller format duplex connector is needed to support QSFP-DD/OSFP 4:1 and SFP-DD 2:1 breakout applications.
MDC (Very Small Form Factor) connectors support these new breakout applications and allow four connectors to be fitted within QSFP-DD module, which LC duplex connector cannot accomplish.
The MDC connector is a Very Small Form Factor (VSFF) duplex optical connector designed for termination of single-mode and multimode fiber cables up to 2.0mm in diameter. It is a 2-fiber connector using proven 1.25mm LC ferrules, providing 3x density over LC. Adapters use the same port cut outs and sizes as LC, allowing current designs to transfer from LC to MDC. MDC solutions include uniboot style jumpers, harnesses, trunks, panels, and many pre-terminated MTP® options.
For high density data centers application, DMSI designed and engineered OMNIA® Next Generation MDC Solutions for guaranteed exceptional optical performance and optimal stability exceeding the requirements of Telcordia GR-326. (https://www.dmsimfg.com/mdc/)