Which 10G SFP+ Optics Are Compatible with Intel X520 Adapter?

The escalating deployments of servers with multi-core processors and demanding applications are driving the need for 10 Gbps connections. Intel X520 10 GbE Adapter is the most flexible and scalable Ethernet adapters for today’s demanding data center environments. At the same time, 10G SFP+ optics play the most important role for its 10G connectivity. But seriously, do you know which 10G SFP+ optics are compatible with the Intel Ethernet converged network adapter X520 series? This blog will give you solutions.

Intel X520 Adapter

Intel X520 adapter is powered by reliable and proven 10G Ethernet technology, which offers high performance for high-IO intensive applications and showcase the next generation in 10 GbE networking features for the enterprise network and data center. It is designed for multi-core processors, which supports for technologies such as multiple queues, receive-side scaling, multiple MSI-X vectors and Low Latency Interrupts. It addresses the demanding needs of the next-generation data center by running mission-critical applications in virtualized and unified storage environments. In a multicore platform, the Intel X520 adapter supports Intel I/O Virtualization Technology (IOVT), which helps accelerate data across the platform, therefore improving application response times. For virtualized environments, it offers advanced features with VMDq (Virtual Machine Device Queues) that lower processor utilization and increase I/O performance.

Intel X520 Dual Port 10GbE SFP+ Adapter

Figure 1. Intel X520 Dual Port 10GbE SFP+ Adapter

The Intel X520 adapter provides SFP+ based connectivity options (fiber or DAC cabling). Intel X520 adapters are provided with 7 models: X520-QDA1, X520-DA2, X520-SR1, X520-SR2, X520-DA1OCP, X520-DA2OCP and X520-LR1. X520-SR1 is shipped with 1 SR SFP+ Optic,  X520-SR2 has dual-port and is shipped with 2 SR SFP+ Optics, X520-LR1 has single-port and is shipped with 1 LR SFP+ Optic, and X520-DA2 has dual-port and does not ship with any optics or cables, which is the most suitable one for 10G SFP+ Optics and the most popular one on the market. The following table lists the detailed information of Intel X520 adapter series in Table 1.

Intel X520 Adapter Product Code Connector and Cable Cable Type Ports
X520-QDA1 QSFP+ direct attach copper (4x10GbE mode) QSFP+ direct attached twinaxial cabling up to 10m Single port
X520-SR1 Fiber optic MMF up to 300 m Single port
X520-SR2 Fiber optic MMF up to 300 m Dual port
X520-DA2 SFP+ direct attach copper SFP+ direct attached twinaxial cabling up to 10 m Dual port
X520- LR1 Fiber optic SMF up to 10 km Single port
X520-DA1OCP SFP+ direct attach copper SFP+ direct attached twinaxial cabling up to 10 m Single port
X520-DA2OCP Copper SFP+ direct attached twinaxial cabling up to 10 m Dual port

Table 1: Intel X520 Series Adapters

10G SFP+ Optics for Intel X520 Adapter

A 10 Gigabit Ethernet network is essential for businesses that demand high bandwidth for virtualization and fast backup and restore for an ever-growing amount of data. To ensure maximum flexibility, Intel X520 adapters supports the ability to mix any combination of the SFP+ optical modules, direct attach copper cables or 1000BASE-T SFP modules. Besides, 10G SFP+ Optics are available in both short range (SR) 850 nm and long range (LR) 1310 nm options. This enables customers to create the configuration that meets the needs of their data center environment.

10G SFP+ Optical Modules

Intel Ethernet SFP+ SR optics and Intel Ethernet SFP+ LR optics are the only 10 Gbps optical modules supported. Other brands of SFP+ modules are not allowed and can’t be used with the X520 adapters. The following table lists the supported 10Gb Ethernet SFP+ optical transceivers for Intel X520 adapters in Table 2. (Note: Other brands of SFP+ optical modules will not work with the Intel Ethernet Server Adapter X520 Series.)

10G SFP+ Optical Modules
Name Intel Product Code (MFG PART#) FS P/N Type
Intel 10G SFP+ SR Optical module E10GSFPSR SFP-10GSR-85 Dual Rate 10GBASE-SR/1000BASE-SX
Intel 10G SFP+ LR Optical module E10GSFPLR SFP-10GLR-31 Dual Rate 10GBASE-LR/1000BASE-LX

Table 2: 10G SFP+ Optical Transceivers for Intel X520 Adapters

1000BASE-T SFP Modules

Some 1000BASE-LX and 1000BASE-SX modules can work with Intel Ethernet Converged Network Adapter X520 series. These modules referred to only highlight specifications and compatibility with Intel Ethernet server adapter X520 series. The table lists tested modules in Table 3. Other similar modules may work but have not been tested (many similar modules can be purchased in FS.COM). Remind you to use your own discretion and diligence to purchase modules with suggested specifications from any third party.

1000BASE-T SFP Modules
Name Intel Product Code (MFG PART#) FS P/N Type
Avago Gigabit Ethernet Module ABCU-5710RZ SFP-GB-GE-T 1000BASE-SX
Intel Gigabit Ethernet Module TXN22120 SFP1G-LX-31 1000BASE-LX

Table 3: 1000BASE-T SFP Modules for Intel X520 Adapters

10G SFP+ Direct Attach Copper Cables (10G SFP+Cu)

A direct attach twinaxial cable is a 2-pair shielded copper cabling terminated with SFP+ electrical modules. Intel X520 Adapters require that any SFP+ passive or active limiting direct attach copper cable should comply with the SFF-8431 v4.1 and SFF-8472 v10.4 specifications. SFF-8472 Identifier must have value 03h (You can verify the value with the cable manufacturer). Maximum cable length for passive cables is 7 meters. Support for active cables requires Intel Network Connections software version 15.3 or later. The following table lists the fully compatible 10Gb DAC cables for Intel Ethernet server adapter X520 series in Table 4.

10G SFP+ DAC Cables
Name Product Code (MFG PART#) FS P/N Type
Intel Ethernet SFP+ Twinaxial Cable, 1 meter XDACBL1M SFP-10G-DAC 10G SFP+ Passive Direct Attach Copper Twinax Cable
Intel Ethernet SFP+ Twinaxial Cable, 3 meter XDACBL3M SFP-10G-DAC 10G SFP+ Passive Direct Attach Copper Twinax Cable
Intel Ethernet SFP+ Twinaxial Cable, 5 meter XDACBL5M SFP-10G-DAC 10G SFP+ Passive Direct Attach Copper Twinax Cable

Table 4: 10G DAC cables for Intel X520 Adapters

QSFP+ Breakout Cables

The new QSFP+ single-port X520-QDA1 can connect the server to the latest 40GbE switches with a single cable operating in 4x10GbE mode. This adapter can also utilize existing 10GbE SFP+ switches using the QSFP+ to 4xSFP+ breakout cable. The QSFP+ adapter supports direct attach copper cables and Intel Ethernet QSFP+ SR optical transceivers. Intel Ethernet QSFP+ breakout cables have one QSFP+ connector on one end and break out into four SFP+ connectors on the other end for direct attachment to SFP+ cages. The following table lists the Intel Ethernet QSFP+ breakout cables for Intel adapter X520-QDA1 in Table 5.

Intel Ethernet QSFP+ Breakout Cables for Intel Adapter X520-QDA1
Name Product Code (MFG PART#) FS P/N
Intel Ethernet QSFP+ breakout cable, 1 meter QSFP-4SFP10G-CU1M QSFP-4SFP10G-DAC
Intel Ethernet QSFP+ breakout cable, 3 meter QSFP-4SFP10G-CU3M QSFP-4SFP10G-DAC
Intel Ethernet QSFP+ breakout cable, 5 meter QSFP-4SFP10G-CU5M QSFP-4SFP10G-DAC

Table 5: QSFP+ Breakout Cables for Intel Adapter X520-QDA1


From what we have discussed, 10G SFP+optics are determined to the data transmission of Intel X520 adapters. SFP+ SR Optics, SFP+ LR optics, 1000BASE-T SFP modules, 10G SFP+ direct attach copper cables and QSFP+ breakout cables are available stock in FS.COM. All SFP+ cables are 100% tested to ensure the compatible and quality. Welcome to visit www.fs.com.

Overview of Bi-Directional Transceiver Modules

During optical transmission process, it’s no wonder that using one fiber to receive data from networking equipment, and another one to transmit data to the networking equipment. This kind of transmission mode will increase investment cost certainly. Luckily, here is a type of transceiver can solve this problem. It’s bi-directional transceiver. Today, this article will take you to make sense why bi-directional transceiver can make it possible to transmit data over one fiber.

Basics of BiDi Transceiver

BiDi is short for bidirectional. BiDi transceiver is a type of fiber optic transceivers which is used WDM (Wavelength Division Multiplexing) bi-directional transmission technology so that it can achieve the transmission of optical channels on a fiber propagating simultaneously in both directions. BiDi transceiver is only with one port which uses an integral bidirectional coupler to transmit and receive signals over a single fiber optical cable. Thus, it must be employed in pairs.

How Does BiDi Transceiver Work?

The obvious difference between BiDi transceivers and traditional two-fiber fiber optic transceivers is that BiDi transceivers are fitted with Wavelength Division Multiplexing (WDM) couplers, also known as diplexers, which combine and separate data transmitted over a single fiber based on the wavelengths of the light. For this reason, BiDi transceivers are also referred to as WDM transceivers.

To work effectively, BiDi transceivers must be deployed in matched pairs, with their diplexers tuned to match the expected wavelength of the transmitter and receiver that they will be transmitting data from or to.

For example, if paired BiDi transceivers are being used to connect Device A (Upstream) and Device B (Downstream), as shown in the figure below, then:

  • Transceiver A’s diplexer must have a receiving wavelength of 1550nm and a transmit wavelength of 1310nm
  • Transceiver B’s diplexer must have a receiving wavelength of 1310nm and a transmit wavelength of 1550nm


Common Types of BiDi Transceiver
BiDi SFP Transceiver

BiDi SFP transceiver is typically applied for the high-performance integrated duplex data link over a single optical fiber. It interfaces a network device mother board (for a switch, router or similar device) to a fiber optic or unshielded twisted pair networking cable. And the most typical wavelength combination is 1310/1490 nm, 1310/1550 nm, 1490/1550 nm and 1510/1570 nm. This BiDi SFP transceiver is used in optical communication for both telecommunication and data bidirectional communications applications.


BiDi SFP+ Transceiver

BiDi SFP+ transceiver is an enhanced SFP transceiver. It is designed for bi-directional 10G serial optical data communications such as IEEE 802.3ae 10GBASE-BX by using 1330/1270nm transmitter and 1270/1330nm receiver. And its transmission distance is up to 20 km.


BiDi X2 Transceiver

BiDi X2 transceivers are designed for bi-directional 10G serial optical data communications, which likes BiDi SFP+ transceivers. The transceiver consists of two sections: the transmitter section uses a multiple quantum well 1330/1270nm DFB laser. And the receiver section uses an integrated 1270/1330nm detector preamplifier (IDP) mounted in an optical header and a limiting post-amplifier IC. This BiDi transceiver is mainly used in Ethernet network.


Advantages of BiDi Transceiver

The obvious advantage of utilizing BiDi transceivers, such as BiDi SFP+ and BiDi SFP transceivers, is the reduction in fiber cabling infrastructure costs by reducing the number of fiber patch panel ports, reducing the amount of tray space dedicated to fiber management, and requiring less fiber cable.

While BiDi transceivers (a.k.a. WDM transceivers) cost more to initially purchase than traditional two-fiber transceivers, they utilize half the amount of fiber per unit of distance. For many networks, the cost savings of utilizing less fiber is enough to more than offset the higher purchase price of BiDi transceivers.


In summary, BiDi transceivers can combine and separate data transmitted over a single fiber based on the wavelengths of the light. That is to say, to achieve the same transmitting result, it needs less money. Except for above SFP & SFP+ BiDi transceivers, FS.COM also provides 40G BiDi transceiver. This BiDi transceiver has two 20 Gbps channels, each transmitted and received simultaneously on two wavelengths over a single MMF strand (OM3 or OM4). Any one of the transceivers would meet your different application requirements with high performance.

SFP+ Transceiver – Do You Know Its Testing Challenges?

Owing to its ubiquity, simplicity and low cost, Ethernet, one technology enabling Internet communications, is everywhere, from carrier networks to local area networks, from desktop PCs to the largest supercomputers. And with its widespread deployment, there occurs countless equipment accordingly designed for Gigabit communications, such as SFP+ transceiver. Are you familiar with SFP+? How much do you know about its testing challenges? This text will discuss some key features of SFP+ firstly, and then delve into its testing challenges.

SFP+ Transceiver Background

As an enhanced version of the small form-factor pluggable (SFP), the enhanced SFP (SFP+) is a hot-pluggable, small-footprint, and multi-rate optical transceiver accessible for up to 16 Gbit/s data communications and storage-area network (SAN) applications. And this SFP+ enjoys the following advantages.

Smaller, Cheaper, More Efficient

Just as the last paragraph mentioned above, the SFP+ module is a variant of the SFP optical transceiver. It simplifies the functionality of the 10G optical module significantly by moving functions, such as clock and data recovery (CDR), electronic dispersion compensation (EDC), 10G SERDES, and signal conditioning. Thus, the SFP+ module requires fewer components, consumes less power, and allows for increased port density. Certainly, it’s also smaller and less expensive compared with the 10-Gigabit small form-factor pluggable module (XFP) form factor.

SFP+, smaller than XFP

As SFP+ becomes more prevalent, it’s imperative for engineers to become familiar with some of the key challenges linked to testing SFP+ capable devices.

SFP+ Transceiver Testing Challenges

On one hand, SFP+ gives a hand in reducing the overall system cost. On the other, its physical layer (PHY) and performance are put with new burdens. The SERDES framer interface (SFI) between the host board and the SFP+ module displays great design and testing challenges.

  • One challenge attributes to the increased port density and the testing time required for 48 or more ports per rack. For instance, there are 15 measurements each for the host transmitter tests, and each of these measurements using manual methods can easily take from three to five minutes. This means it will take engineers more than an hour per port to complete the required tests.
  • The second one that engineers need to consider is: if a measurement fails, how can they determine which component is causing such a failure, and how they debug the issue to arrive at the root cause. Such determinations are especially challenging because of the tight physical packaging and compact designs.
  • Another challenge falls on the connectivity. That is: how to get the signal out from the device under test (DUT) to an oscilloscope. Test fixtures are typically required, but questions arise around consequently: whether the fixtures have been tested and validated against the specification.
  • The additional problem lies in the fact that the SFP+ specification requires some measurements to be performed using a PRBS31 signal. At a sampling rate of 50 Gsamples/s, the designer can acquire around 40 million unit intervals (UIs). At a sampling rate of 100 Gsamples/s, the instrument can acquire 20 million UIs. However, a PRBS31 pattern has more than 2 billion UIs. Hence, acquiring an entire pattern poses a challenge.

SFP+ transceiver with its compact size has become a popular industry format supported by many network component vendors. And with the above-mentioned points in mind, designers have gained an overview of SFP+ transceiver testing challenges. Fiberstore is an outstanding and professional SFP+ manufacturer and supplier, available with a sea of high-performance and -quality SFP+ transceivers. Besides SFP+transceiver, Fiberstore also supplies QSFP+ transceiver, fully compatible with major brands. For more information about transceivers, you can visit Fiberstore.

SFP+ Transceiver Testing – TWDPc Measurement

SFP+ transceiver is widely deployed in applications and becomes much more pervasive due to its smaller form factor, less power consumption and its increased port density compared with XFP transceiver. Each SFP+ transceiver houses an optical receiver and transmitter. One end of the transceiver is an optical connection complying with the 10GbE and 8GFC standards, while the other end is an SERDES framer interface (SFI) serial interconnect handling differential signals up to 10 Gbit/s. In order to keep a SFP+ transceiver achieving high performance, the engineers need to acquaint with the key challenges related to testing SFP+ transceiver. This article will first walk through the SFP+ testing challenges and then focus on one kind of testing measurement.

SFP+ Testing Challenges
  • One obvious challenge is the increased port density and the testing time required with 48 or more ports per rack.
  • Another challenge is moving seamlessly from a compliance environment to a debug environment.
  • Yet another problem most designers face today relates to connectivity: how to get the signal out from the device under test (DUT) to an oscilloscope.
  • Another challenge to prepare for is that the SFP+ specification calls out some measurements to be performed using a PRBS31 signal.
  • Additionally, acquiring a record length of 200 million data points demands huge processing power and time.
TWDPc Measurement

TWDPc, short for transmitter waveform distortion penalty for copper, requires a special algorithm defined by the SFP+ specification. This test is defined as a measure of the deterministic dispersion penalty due to a particular transmitter with reference to the emulated multimode fibers and a well-characterized receiver.


The TWDPc script (of 802.3aq, 10GBASE-LRM) processes a PRBS9 pattern requiring at least 16 samples per unit interval. Out of concern for the large installed base of equivalent-time oscilloscopes with a record length of around 4000 samples, the requirement for 16 samples per unit interval was relaxed to seven samples per unit interval.

The relaxation of the requirement from 16 samples per unit interval to just seven samples per unit interval causes worst-case pessimism of 0.24 dB TWDPc over 30 measurements. For DUTs that already have a high TWDPc, 0.24 dB can be the difference between a pass or a fail result.

The TWDPc measurement for SFP+ host transmitter output specifications for copper requires more than 70 Gsamples/s to capture a minimum of seven samples per UI. Real-time oscilloscopes offering higher sampling rates of 100 Gsamples/s or greater have a much higher chance of providing accurate results for TWDPc compared to scopes that only offer lower sampling-rate options.

Across the board, it is important to map the SFP+ signal’s data-transfer rate to the proper oscilloscope bandwidth requirements to ensure accuracy in measurement and margin testing. With a 10.3125-Gbyte/s data-transfer rate and minimum rise time of 34 ps, a scope with a bandwidth of 16 GHz or higher is required to meet the minimum requirements for SFP+. As noted, sampling rate is also an important consideration for the TWDPc measurement.


Although SFP+ transceiver simplifies the functionality of the 10G optical module, it introduces some test and measurement challenges. TWDPc is a key test for SFP+ transceiver. It defines the differences (in dB) between a reference signal and noise ratio (SNR) and the equivalent SNR at the slicer input of a reference equalizer receiver for the measurement waveform after propagating through a stimulus channel. For SFP+ compliance testing, TWDPc is a required measurement.