SFP28 and QSFP28 Optical Modules For 25 Gigabit Ethernet

The widely acknowledged Ethernet speed upgrade path was 10G-40G-100G. However, a new development indicates the latest path for server connection will be 10G-25G-100G with potential for future upgrading to 400G. But why 25G? Because moving from 10G to 40G is a big jump and it turns out the incremental cost of 25G silicon over 10G is not that great. This new standard will require improved cables and transceiver modules capable of handling this additional bandwidth, under this circumstance, QSFP28 and SFP28 are promoted.

25GbE Ethernet—An Emerging Standard
25 Gigabit Ethernet (25GbE) has passed the first hurdle in the IEEE standards body with a successful Call for Interest (CFI) in July, 2014. It is a proposed standard for Ethernet connectivity that will benefit cloud and enterprise data center environments. 25GbE leverages technology defined for 100 Gigabit Ethernet implemented as four 25-Gbit/s lanes (IEEE 802.3bj) running on four fibers or copper pairs. The follow picture shows 25G Access Network.

Significant Performance Benefits—25G Over 40G
The value of 25GbE technology is clear in comparison to the existing 40GbE standard. Obviously, 25GbE technology provides greater port density and a lower cost per unit of bandwidth for rack server connectivity. For applications that demand substantially higher throughputs to the endpoint, there exists 50GbE—using only two lanes instead of four—as a superior alternative to 40GbE in both link performance and physical lane efficiency.

The proposed 25GbE standard delivers 2.5 times more performance per SerDes lane using twinax copper wire than that available over existing 10G and 40G connections. A 50GbE link using two switch/NIC SerDes lanes running at 25 Gb/s each delivers 25% more bandwidth than a 40GbE link while needing just half the number (four) of twinax copper pairs. Therefore, a 25GbE link using a single switch/NIC SerDes lane provides 2.5 times the bandwidth of a 10GbE link over the same number of twinax copper pairs are used in today’s SFP+ direct-attach copper (DAC) cables.

Perhaps the most important benefit of 25GbE technology to data-center operators is maximizing bandwidth and port density within the space constraints of a small 1U front panel. It also leverages single-lane 25Gb/s physical layer technology developed to support 100GbE.

Cloud Will Drive to QSFP28 and SFP28
QSFP28 is used for 4x25GE and SFP28 is used for a single 25GE port. SFP28 module, based on the SFP+ form-factor, suports the emeraging 25G Ethernet standard. It enables error-free transmission of 25Gb/s over 100m of OM4 multi-mode fiber and a new generation of high-density 25 Gigabit Ethernet switches and network interface cards, facilitating server connectivity in data centres, and a conventional and cost-effective upgrade path for enterprises deploying 10 Gigabit Ethernet links today in the ubiquitous SFP+ form factor.

The QSFP28 (25G Quad Small Form-Factor Pluggable) transceiver and interconnect cable is a high-density, high-speed product soluon designed for applicaons in the telecommunicaons, data center and networking markets. The interconnect offers four channels of high-speed signals with data rates ranging from 25 Gbps up to potentially 40 Gbps, and will meet 100 Gbps Ethernet (4x25 Gbps) and 100 Gbps 4X InfiniBand Enhanced Data Rate (EDR) requirements.

The demonstration showed QSFP28-SR4 modules and a compatible Finisar FTLX1471D3BCL 10GBASE-LR SFP+. The QSFP28 SR4 module is a vertically integrated solution that meets IEEE 802.3 standards and MSA requirements with power dissipation well under 3.5W. The module supports both 100GBASE-SR4 as well as 4x25G breakout applications. Both the QSFP28 SR4 and SFP28-SR modules are sampling now.

Conclusion
The dominant next-generation server connection speed is going to be 25G as it providing a cost competitive longer reach option for mainstream customers. Fiberstore is excited to introduce several products that will drive the next generation of data centre and enterprise interconnects. We currently do not supply 100G QSFP28 and 25G SFP28 based switches, but we do manufacture a full range of tranceivers, such as SFP+, X2, XENPAK, XFP, SFP, GBIC, CWDM/DWDM, 40G QSFP+ & CFP, etc. Compatible Finisar FTLX1471D3BCL and FTLF8524P2BNL are offered with minimum price and high quality. If you are interested, please feel free to contact us.

Reference:
http://www.ieee802.org/3/cfi/0714_1/CFI_01_0714.pdf

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 Modules—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.

XENPAK—the first 10GbE pluggable transceiver optics. Presents SC connectors
X2—the successor to the XENPAK (the smaller brother of the XENPAK). Presents SC connectors
XFP—the first of the small form factor 10GbE optics and newest pluggable transceiver. Presents LC connectors
SFP+—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. Fiberstore, as a professional optical transceiver modules manufacturer, supplies a complete range of 10G transceiver modules that can be customized as well. SFP-10G-ER, HP J9150A, F5-UPG-SFP+-R, Finisar FTLX1471D3BCL, QFX-SFP-10GE-SR—these compatible 10G transceiver modules are all available at Fiberstore. If you want to know more about 10G transceiver modules, welcome to contact us.

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