CFP, short for C form-factor pluggable, is a multi-source agreement to define the form-factor of optical transceiver for the transmission of high-speed digital signals. The c stands for the Latin letter C used to express the number 100 (centum), since the standard was primarily developed for 40Gbit/s and 100Gbit/s interfaces for Ethernet, Telecommunications and other applications. The electrical interface will vary by application, but the nominal signaling lane rate is 10Gbit/s per lane and documentation is provided for CAUI, XLAUI, OTL4.10, OTL3.4, and STL256.4 electrical interface specifications.

XENPAK is a multisource agreement (MSA) for a 10 Gigabit Ethernet (10GbE) transceiver package. It’s the oldest 10G fiber optic transceiver. XENPAK transceivers is designed with XAUI interface and Digital Diagnostic Monitor Interface, which comply with the XENPAK MSA protocol and satisfy the application of 802.3ae Ethernet protocol 10GB. XENPAK transceivers are supplied for physical layer interfaces supporting multi-mode and single mode fiber optic cables and InfiniBand copper cables with connectors like as CX4. Transmission distances vary from 100 metres (330 ft) to 80 kilometres (50 mi) on fiber and up to 15 metres (49 ft) on CX4 cable. Newer XENPAKs using the 10GBase-LX4 standard operated using multiple wavelengths on legacy multi-mode fibres at distances of up to 300 metres (980 ft), eliminating the need to reinstall cable in a building when upgrading certain 1 Gbit/s circuits to 10 Gbit/s.

SFP+ is a next-generation, hot-pluggable, small-footprint, serial-to-serial, multi-rate optical transceiver that commonly used in 8.5GbE to 11GbE data communications and storage-area network (SAN). It is a variant of the conventional SFP optical transceiver with enhancement interface defined in SFF-8074i, SFP+ with a similar size of SFP and compliant to SFF-8472 (digital diagnostic interface for optical transceivers) that gives the end user the ability to monitor real-time parameters of the SFP, such as optical output power, optical input power, temperature, laser bias current, and transceiver supply voltage. The SFP+ module is a variant of the SFP optical transceiver.

As defined in X2 Multi-Source Agreement, the X2 transceiver is a compact 10 Gigabit/s optical transceiver designed to use a side rail support system that allows the heat sink and front bezel to be easily adapted to the different needs of the key 10 Gb/sec markets. The structure of the X2 rail system has been carefully designed to allow unblocked airflow over the full length of the top surface area, irrespective of direction. X2 can be mounted on the front panel, mid board, or on a “conventional” PCI or compact PCI “blade”. The ability to support different height variants, without changing the side rail support, is also a key X2 strength.