Difference between xfp and sfp+

In optical fiber networks, 10G optical modules are widely used in schools, companies, and other application environments due to their lower cost and power consumption. XFP and SFP+ are two common packaging types of 10G optical modules. What's the difference between XFP and SFP+ optical modules? And can they be interconnected?

What is an XFP optical module?

XFP is a packaging of 10G optical modules. It's a standardized encapsulation for serial 10G optical transceivers. The 10G XFP optical module is a hot-pluggable I/O device inserted into 10-gigabit ports, with the motherboard's electrical interface being the standardized 10G serial interface called XFI. It complies with the 10G optical fiber channel, 10G Ethernet, SONET/OC-192, and SDH/STM-64 standards. The XFP optical module can support a maximum transmission distance of 100 kilometers.

XFP is defined by the XFP Multi-Source Agreement (MSA), announced on July 19, 2002, officially launched on March 3, 2003, and underwent minor updates on August 31, 2005. The XFP optical module is a 10G optical module that's hot-pluggable and independent of communication protocols. It can transfer data at wavelengths of 850nm/1310nm/1550nm, primarily used in 10G Ethernet, 10Gbit/s optical fiber channels, OC-192 digital transmission, synchronous optical network STM-64, 10Gbit/s optical transmission network (OTN) OUT-2, and parallel optical fiber links.

What is an SFP+ optical module?

The SFP+ optical module is a 10G optical module with an SFP+ encapsulation. This module features high density, low power consumption, and significantly lower system construction costs. The SFP+ optical module is widely used in 10G Ethernet, SDH optical transmission networks, WDM wavelength division multiplexing system engineering, and single-fiber bidirectional system engineering. SFP+ optical modules have a transmission distance of 300 meters for multimode modules, while single-mode modules can transmit up to 100 kilometers.

SFP+ is an upgraded version of SFP, defined by the SFP+ Multi-Source Agreement (MSA), officially released on May 9, 2006, with version 4.1 released on July 6, 2009. The SFP+ optical module is a small, hot-pluggable 10G optical module, following the IEEE 802.3ae, SFF-8431, and SFF-8432 protocols. It operates at wavelengths of 850nm/1310nm/1550nm and is used in 10G Ethernet, 10G optical fiber channels, 10G SONET/SDH, OTN, CPRI wireless, 16G optical fiber channels, and 32G optical fiber channels.

Differences between SFP+ and XFP:

(1) They have different appearances, with SFP+ being smaller than XFP.

(2) They have different functions. Compared to the SFP+ optical module, the XFP optical module has signal modulation functions, serial/deserializer, MAC, clock, and data recovery (CDR), as well as electronic dispersion compensation (EDC) functions. So when a switch or router doesn't have these functions integrated on its motherboard, the XFP optical module is needed.

(3) They follow different protocols. XFP adheres to the XFP MSA protocol, while SFP+ follows the IEEE 802.3ae, SFF-8431, and SFF-8432 protocols.

(4) Both SFP+ and XFP are 10G optical modules, and they can interoperate with other types of 10G modules.

(5) SFP+ is a more mainstream design.

Can XFP and SFP+ optical modules interconnect?

As long as they have the same transmission rate, transmission distance, and wavelength, they can be interconnected using optical fibers. For example, a 10G XFP optical module with a wavelength of 1310nm and a transmission distance of 10KM can connect with a 10G SFP+ optical module with the same wavelength and distance. Although the market's transmission rate for optical modules has risen to 200G, it doesn't mean that 10G optical modules will exit the market. Currently, 10G optical modules remain mainstream. Due to differences in size, structure, and compatibility between XFP and SFP+ optical modules, they cannot replace each other.

Can a 10G XFP optical module connect with a 10G SFP+ optical module?

Since the 10G XFP optical module and the 10G SFP+ optical module have the same transmission rate (referring to the 10G transmission rate) and wavelength (supporting 850nm/1310nm/1550nm), they can coexist within the same Ethernet. This means that if the XFP and SFP+ optical modules have the same parameters, they can connect. For example, a 10G XFP optical module with a wavelength of 1310nm can connect with a 10G SFP+ optical module with the same wavelength. However, it's essential to note that XFP and SFP+ optical modules cannot replace each other. The typical interconnection application between the 10G XFP optical module and the 10G SFP+ optical module is illustrated below.

In this scheme, the Fast (FS) 10G XFP optical module with a wavelength of 850nm and the 10G SFP+ optical module with the same wavelength are respectively plugged into the Cisco ME-3600X 24CX switch (with four 10G XFP ports) and the Cisco WS-C3850-12XS-S switch (with twelve 10G SFP+ ports). They then achieve short-distance 10G optical network transmission through LC duplex multimode optical fibers.

All in all, the choice between XFP and SFP often depends on the requirements of the application and the specifications of the network equipment. When you need a speed of 10 Gbps and your device supports XFP, then XFP is an excellent choice. However, if your device supports SFP, or if you have needs for different speeds and applications, SFP might be the better option.
Although the industry has successively introduced 25G/40G/100G/400G Ethernet to cater to users' demands for greater bandwidth and faster speeds, it doesn't imply that 10G Ethernet will be phased out. 10G optical modules remain mainstream. Meanwhile, due to differences in size, structure, and compatibility between XFP and SFP+ modules, the two cannot be used interchangeably.