In fiber optic networking, optical module is the indispensable building block and the enabler of seamless data transmission. 10G fiber optic transceivers are still the mainstream in the access of data center due to the lower cost and lower power consumption. XFP module and SFP+ transceiver both work at 10G data rate, but what are the differences between XFP and SFP+ optical modules and how about their inter-compatibility? Can we connect XFP with SFP+ module? Find all the answers in the following descriptions.
10G XFP vs SFP+ modules: the differences will be elaborated on this section from the aspects of definitions and features.
XFP optical transceiver is the first 10G module that appeared in the market. It was publicly released on July 19, 2002, adopted on March 3, 2003, and updated lightly through August 31, 2005. It is a 10 Gigabit small form factor pluggable transceiver and it is defined by XFP MSA. Operating at wavelength of 850nm, 1310nm or 1550nm, XFP transceivers are protocol-independent and fully compliant to the following standards: 10 Gigabit Ethernet, 10 Gbit/s Fibre Channel, synchronous optical networking (SONET) at OC-192 rates, synchronous optical networking STM-64, 10 Gbit/s Optical Transport Network (OTN) OTU-2, and parallel optics links.
SFP+ transceiver is an enhanced version of SFP, which is defined by SFP+ MSA. It was first published on May 9, 2006, and version 4.1 published on July 6, 2009. SFP+ module supports data rates up to 16 Gbit/s. It also supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. 10G SFP+ module can be applied for SONET OC-192, SDH STM-64, OTN G.709, CPRI wireless, 16G Fibre Channel, and the emerging 32G Fibre Channel application.
The following figure shows a basic specification of XFP 10G and SFP+ optical transceivers.
|Stands For||10 Gigabit Small Form Factor Pluggable||Small Form-factor Pluggable plus|
|Standard||IEE802.3ae; XFP MSA||IEE802.3ae; SFF-8431; SFF-8432|
|Data Rate||10Gbps||6Gbps; 8.5Gbps; 10Gbps|
|Wavelength||850nm/1310nm/1550nm; 1310nm/1490nm/1550nm; 1270nm-1610nm; ITU17~ITU61||850nm/1310nm/1550nm; 1270nm/1330nm; 1270nm-1610nm; ITU17~ITU61|
|Connector||LC Duplex||LC Duplex|
|Transmission Distance||220m/300m/2km/10km/20km/40km/60km/80km/ 120km||300m/2km/10km/15km/ 20km/40km/60km/80km/100km/120km/150km|
Both XFP module and SFP+ module are 10G fiber optical modules and they are mainly used in 10G fiber optic networking. The detailed features are presented below.
Form Factor: XFP offers a bigger footprint than the SFP+ modules, so they are not interchangeable.
Standard: XFP is based on the standard of XFP MSA, while SFP+ is an enhanced version of the SFP and is based on the SFP+ MSA.
Date Rate: XFP is compliant to 10 Gbit/s Fibre Channel, whereas SFP+ supports 8 Gbit/s Fibre Channel.
In comparison to XFP, SFP+ leaves more circuitry to be implemented on the motherboard instead of inside the module because it moves some functions to motherboard, including signal modulation function, MAC, CDR and EDC.
For 10G cable, SFP+ introduces Direct Attach Cable (DAC) for connecting two SFP+ ports without dedicated transceivers, but XFP has no cable version.
The SFP module can be used on the SFP+ ports while XFP ports only accept XFP modules.
10G XFP and SFP+ transceivers can be inter-compatible in one Ethernet network due to the fact that they have the same data rates and wavelengths. That means they can be used at opposite ends of a physical link, as long as they conform to the same wavelength and signaling rate. More specifically, SFP+ and XFP are with the same specification. For example, the XFP 10G 1310nm transceivers can work with the SFP+ 10G 1310nm modules. Please remember that XFP and SFP+ optical transceivers are not interchangeable.
The following figure shows a typical interconnection application with XFP and SFP+ modules. FS Generic 10GBASE-SR XFP and SFP+ transceivers are plugged into the Cisco ME-3600X 24CX (with four XFP ports) and Cisco WS-C3850-12XS-S (with twelve SFP+ ports) switches respectively. Both of these two modules are working at 850nm for short distance transmission. The XFP and SFP+ transceivers are connected by an OM3 multimode LC duplex fiber optic patch cable.
Figure 1: XFP vs SFP+: Interconnection Application
With the increasing demands for higher data rate and bandwidth, 25G, 40G, 100G, and 200G Ethernet network are emerging in the market. But this doesn’t mean that 10G Ethernet will step out of the market. SFP+ transceivers are still the mainstream with a smaller size, lower consumption and lower cost. Though the XFP transceiver module is not as popular as SFP+ transceiver, it still can not be replaced by SFP+ modules in some 10G network applications. XFP and SFP+ modules can be used at the end of the point-to-point fiber links but can’t be interchanged.
Related Article: Wavelength Switching Solution: Tunable XFP Transceiver