Compact SFP is more and more demanded, thanks to the increasing internet traffic. Normally, you would get a single connection per fiber cable. Bi-Di transceivers are used for 2 connections through a single cable. Now, CSFP (or Compact Small Form-Factor Pluggable) makes it possible to have 4 connections.
What is the Compact SFP?
CSFP uses the SFP common interface. Both of its ports are Bi-Directional; they provide double the capacity as compared to the regular Bi-Di. Each port works on a single fiber, without the need for any other additional optical fiber.
The end host equipment must use Bi-Directional SFP that is in compliance with the wavelengths on the CSFP. The CSFP transceivers are multi-service supporting from 100Mbps to 1.25Gbps, entailing Ethernet, Fiber Channel and SDH/SONET services.