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November 11, 2015

Unveiling 10G Transceiver Modules

As the core of optoelectronic device in the WAN, MAN or LAN application, fiber optic transceivers have developed various types along with the increasing in complexity. Take 10G transceiver module as an example, it has experienced developments from XENPAK, X2, XFP and finally realized with SFP+. Many users raised the questions related to the main difference between these optical modules. So, in the following part, we will provide some main tips about the difference among the XENPAK, X2, XEP and SFP +.

Four Transceiver Modulesâ€”Description &Comparison

Those four transceivers (see in Figure 1) are all used to transmit 10G signal using Ethernet protocol. They are the result of Multi-Source Agreement (MSAs) that enable vendors to produce 802.3ae-compliant pluggable transceivers. The following part will provide a general guide to these module types.

10G transceiver modules

XENPAKâ€”the first 10GbE pluggable transceiver optics. Presents SC connectors

X2â€”the successor to the XENPAK (the smaller brother of the XENPAK). Presents SC connectors

XFPâ€”the first of the small form factor 10GbE optics and newest pluggable transceiver. Presents LC connectors

SFP+â€”a 10GbE optics using the same physical form factor as a gigabit SFP. Because of this, many of the small SFP+ based 10GbE switches use 1G/10G ports, giving an added degree of flexibility. Presents LC connectors.

The first published XENPAK was by far the largest in physical size, which totally limited its popularity on the market. Many vendors then began to work on alternative standards. Finally in 2003, MSAs published another two 10G transceiver modules called X2 and XFP. X2 and XFP modules have been developed that support all of the high-power, long-distance applications once reserved for the larger XENPAK transceivers. But nowadays, SFP+ has gradually replaced the XFP and becomes the main stream of 10G transceivers markets. Why? The following part will answer you.

Contrast Between XFP and SFP+

XFP modules are hot-swappable and protocol-independent. They typically operate at near-infrared wavelengths of 850nm, 1310nm or 1550nm. They can operate over a single wavelength or use dense wavelength-division multiplexing techniques. SFP+ published on May 9, 2006, is an enhanced version of the SFP that supports data rates up to 16 Gbit/s. SFP+ supports 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. It is a popular industry format supported by many network component vendors. Although the SFP+ standard does not mention 16G Fibre Channel, it can be used at this speed.

Both SFP+ and XFP are 10G transceivers, and can connect with other 10G transceivers. The main reason why SFP+ gain more market share than XFP is that SFP+ is more compact sized than XFP. The smaller SFP+ transfers the modulation functions, serial/deserializer, MAC, clock and data recovery (CDR) and EDC functions from the module to the motherboard on the card. In addition, cost of SFP+ is lower than XFP. Because XFP relies on a high-speed interface (10.3125Gbps), high-priced serializer/deserializer (SERDES) is required inside the switch to support it. They add an unacceptable cost to the base system of XFP. XFP complies with protocol of XFP MSA while SFP+ complies with IEEE802.3, SFF-8431, SFF-8432. SFP+ is the mainstream design currently.

Conclusion

SFP+, with its advantages of smaller size, low-cost and meeting the demand of high-density fiber transceivers, is anticipated to give rise to the realization better speed communication networks of the next generation.

Reference:

http://www.cisco.com/c/en/us/td/docs/interfaces_modules/transceiver_modules/compatibility/matrix/10GE_Tx_Matrix.html

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