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40 Gigabit Ethernet (40GbE) is Ethernet with a nominal link rate of 40 gigabits per second (40 Gb/s). The term names the speed, not a particular cable: the chosen physical-layer interface determines the medium, transceiver, connector and supported distance.
What does 40GbE mean?
40GbE describes the nominal rate at which an Ethernet link operates. It does not mean that every application will transfer data at exactly 40 Gb/s; usable throughput depends on the equipment, protocol overhead and traffic conditions.
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IEEE 802.3ba-2010 introduced Ethernet MAC parameters, physical-layer specifications and management parameters for 40 Gb/s and 100 Gb/s. IEEE now marks that amendment as superseded. Its work is incorporated into the broader IEEE 802.3 family; IEEE’s IEEE 802.3-2022 overview describes Ethernet across selected rates from 1 Mb/s through 400 Gb/s and summarizes 802.3ba’s contribution.
IEEE records 802.3ba-2010 as published on June 22, 2010. The IEEE 802.3ba task-force page says the work concluded with approval of the standard at the June 2010 IEEE Standards Board meeting.
#1 Best Overall
- 【Controller】:40GbE PCI-E NIC with Original Intel XL710-BM2 controller, which supports single-root I/O virtualization and improves server stability.
- 【Data Rate】:Dual QSFP+ Ports (1GbE/10GbE/40GbE) let you connect to network cable for meeting the demands of data center environments.PCIe v3.0 (8.0GT/s) x8; X8/X16 Lane.
- 【Technical Support】:On-chip QoS and Traffic management; FPP; Load balancing on multiple CPUs; VMDq; PCI-SIG* SR-IOV; Intel Data Directl/O Technology; TCP checksum offloading capabilities; iSCSI,FCoE,NFS; Jumbo Frames;PXE;DPDK;DCB;Auto-MDIX.
- 【Supported Operating Systems】: Windows, Windows Server, Linux*RHEL, SUSE, Ubuntu, FreeBSD, Vmware ESX/ESXi,UEFI, etc.
- 【What you Get】: Vogzone 40GbE PCI-E X8 Network Card XL710-QDA2-40G (compare to Intel XL710-QDA2 ) x1, Low-profile Bracket x1(NOTE: QSFP adapter is not included in the package).
Which 40GbE interfaces and cables are common?
The PHY (physical-layer interface) specifies how the Ethernet signal travels over a particular medium. These examples illustrate why the label 40GbE alone is not enough to choose a cable or module:
| Interface example | Medium and implementation | Example connector | Cited reach |
|---|---|---|---|
| 40GBASE-SR4 | Multimode fiber; four optical lanes | MPO-12 / MPO-MTP | At least 100 m in the Fiber Optics Tech Consortium overview; the fiber grade affects the supported range. |
| 40GBASE-LR4 | Single-mode fiber; four wavelength lanes multiplexed in the module | Duplex LC in Cisco’s cited module matrix | Up to 10 km in the overview and Cisco module description. |
| 40GBASE-CR4 | Twinax direct-attach copper | QSFP copper direct-attach connection | Up to 7 m in the overview. |
These distances are examples for the cited interfaces, not interchangeable guarantees for every cable, module or installation. The Fiber Optics Tech Consortium’s 40GBASE-SR4 application overview provides the cited reach context. Cisco’s 40GBASE QSFP Modules data sheet describes a broader product range that also includes bidirectional multimode and active optical cable options.
Rank #2
- Transmission rate: 40Gbps
- Interface type: QSFP+ Port *2
- Compatible slots:PCI-E X8, PCI-E X16
- Compatible systems: Windows Server 2003/2008/2012, Windows 7/8/10 */Visa, Linux, ESXi/ESXi*
- The package includes:CX314A network card * 1, high bracket * 1, low bracket * 1
How do SR4 and LR4 differ?
Both are 40GbE optical interfaces, but they use different fiber types and connectors. SR4 is a multimode-fiber option with four lanes and an MPO-style connector in the cited Cisco module description; LR4 is a single-mode option with multiplexed wavelength lanes and a duplex-LC connector in that matrix. The cited examples list SR4 for at least 100 m and LR4 for up to 10 km, subject to the specific module and link requirements.
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1Scan for outdated or missing drivers - takes under a minute2Repair Windows errors before they cause bigger problems3Fix the driver behind crashes, sound loss and screen glitchesCisco’s 40GE transceiver matrix identifies the cited product characteristics: its SR4 module uses 850 nm and MPO-12, while its LR4 module is specified for 10 km over single-mode fiber with duplex LC. These are vendor product descriptions for the listed modules, not universal guarantees for all products bearing those interface names.
Rank #3
- 40GbE QSFP+ NETWORK CARD: Converged network adapter provides high bandwidth to servers and workstations for demanding applications; includes virtualization (VT-c), SAN and iSCSI offload support
- TECH SPECS: 40 Gbps | Open QSFP+ Port, MSA Compliant | Intel XL710 Chip | MMF & SMF Fiber Support | PCIe 3.0 x8 | PXE Boot | 9K Jumbo Frames | VT-c | VLAN | Full & low profile | 2 Yr Warr
- TESTED & VERIFIED PERFORMANCE: We use Spirent SmartBits validation tools to validate performance; Fiber LAN card compatible w/leading servers like Dell PowerEdge HPE ProLiant & Lenovo ThinkSystem
- FLEXIBLE: Use any MSA compliant QSFP+ module / direct attach cable (DAC) supporting different fiber types; 40GbE Network Interface Card works w/leading switch, router, & device brands like Cisco & HPE
- WIDE HYPEVISOR & OS COMPATIBILITY: 40 Gigabit Ethernet NIC works w/Windows 7, 8, 8.1, 10; Windows Server 2008 R2, 2012, 2012 R2, 2016, 2019; Linux kernels 3.x + (LTS versions); VMWare ESXi 5.0, 5.1+
How to choose a 40GbE transceiver and cable
A 40G QSFP+ transceiver is a module category, not a promise of universal compatibility. Before buying a module or cable, check the exact switch or router model and the entire link:
- Check the equipment. Confirm that both endpoint ports support the specific module or cable you intend to use. Consult the device maker’s compatibility information for the exact model and SKU.
- Match the medium. Choose multimode fiber, single-mode fiber or twinax copper according to the selected PHY and the cabling already installed.
- Match the connector and lanes. Verify the connector at both ends and that the cable or fiber assembly suits the module’s lane arrangement.
- Check the required reach. Compare the actual distance with the module’s specification and the link’s fiber grade or cable requirements. Do not assume one interface’s reach applies to another.
- Confirm both ends. Check that each endpoint supports the chosen optics or cable and that any claimed interoperability applies to those specific devices.
Cisco documents distinct media, connectors and QSFP module options, with interoperability information where applicable. Its product descriptions are useful for those products; they do not establish compatibility for every vendor’s equipment.
Rank #4
- HIGH SPEED DATA TRANSMISSION: The transmission rate of 40Gb Ethernet PCIe card per port up to 40Gbps, and the total transmission rate of double ports is 80Gbps, which is suitable for big data transmission and low latency applications
- ADVANCED HOST CHIP TECHNOLOGY: The 40GbE Ethernet PCIe card uses advanced host chip technology and supports multiple network protocols and functions to ensure high performance and reliability
- PCIE 3.0 BUS INTERFACE: The network card provides PCIe 3.0 interfaces to provide higher data transfer rates and lower latency, and is suitable for modern servers and workstations
- DOUBLE 40GBE NETWORK PORTS: Two 40GbE network ports provide double network connectivity, increasing network flexibility and scalability, useful and practical
- APPLICATION SCENARIOS: Ethernet network card is applicable to data centers, cloud computing platforms, high performance computing clusters, and storage networks
Where is 40GbE used?
Cisco describes its 40G QSFP portfolio for data centers, high-performance computing networks, enterprise core and distribution layers, and service-provider applications. Those are vendor-stated application contexts, not evidence that 40GbE is the best speed for every network or that it has a particular market share.
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