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400G Transceivers Guide

400G Transceivers Guide

400G transceivers, Active Optical Cables (AOCs), and Direct Attach Copper (DAC) cables are critical components for high-speed networking in modern data centers, enterprise networks, and high-performance computing environments. These components support data rates of up to 400 Gigabits per second (Gbps), providing the bandwidth necessary to handle today's data-intensive applications.

Unleashing Ultra-High-Speed Connectivity with 400G Transceivers

JTOPTICS® 400G transceivers are engineered for next-generation data center environments requiring massive bandwidth and ultra-low latency. Ideal for hyperscale, cloud, and AI-driven infrastructures, they support high-density switch interconnects and accelerate data flow across core and spine-leaf networks. With optimized power efficiency and advanced modulation, 400G modules future-proof your network for data-intensive workloads and rapid scalability.
JTOPTICS 400G High-Bandwidth Transceiver for Hyperscale Data Center Applications
JTOPTICS 400G High-Bandwidth Transceiver for Hyperscale Data Center Applications

Frequently Asked Questions

The QSFP-DD form factor is based on the QSFP form factor with an extra row of electrical pins added. It allows strict backwards compatibility with 40G and 100G QSFP modules. To dissipate the larger power of 400G modules, the QSFP-DD relies on an external heatsink that is part of the switch platform – i.e. when a QSFP-DD module is inserted into a QSFP-DD port, the platform must provide a heatsink that makes contact with the QSFP- DD module with sufficient pressure to guarantee a low thermal resistance interface.

The OSFP form factor was designed from the ground up for optimal performance at 400G and 800G. It allows for backwards compatibility to 40G and 100G QSFP optics using the ADPT-O-Q-100G passive adapter. A key difference of the OSFP is that the heatsink is integrated into the module case itself. This has the advantage of ensuring the best possible thermal contact between the power dissipating components and the heatsink, enabling better thermal performance. The OSFP also has approximately 50% more surface area than the QSFP-DD, enhancing the ability of the module to dissipate heat. 

400G platforms allow data centers and high-performance computing environments to address growing needs for higher bandwidth at lower cost and power per gigabit. Key benefits include:

•           Increase switching bandwidth by a factor of 4. Migrating from 100G to 400G systems increases the bandwidth per RU from 3.2-3.6T to 12.8-14.4T / RU.

•           Enable higher density 100G ports using optical or copper breakouts. A 32 port 1RU 400G system enables 128 100GE ports / RU. This enables a single Top of Rack (TOR) leaf switch to connect to multiple racks of servers or Network Interface Cards (NICs).

•           Reduce the number of optical fiber links, connectors, and patch panels by a factor of 4 when compared to 100G platforms for the same aggregate bandwidth.

•           Enable 2-4X lower cost and power / bit, reducing capex and opex.

There are two form-factors defined for 400G optical modules and cables:

•           The OSFP: The OSFP stands for “Octal Small Form-factor Pluggable”. It is described as an “Octal” module because the electrical interface of an OSFP connector consists of 8 electrical lanes, running at 50Gb/s each, for a total of bandwidth of 400Gb/s.

•           The QSFP-DD: The QSFP-DD stands for “Quad Small Form-factor Pluggable (QSFP) – Double Density (DD)”. The electrical interface of a QSFP-DD connector also has 8 electrical lanes, running at 50Gb/s each, for a total bandwidth of 400Gb/s. The QSFP-DD form factor is similar to the QSFP form factor, except a second row of electrical contacts has been added to increase the number of high-speed electrical lanes from 4 (in a QSFP) to 8 (in a QSFP-DD).

No. The OSFP and the QSFP-DD are two physically distinct form factors. If you have an OSFP system, then OSFP optics and cables must be used. If you have a QSFP-DD system, then QSFP-DD optics and cables must be used.

Yes. The OSFP and QSFP-DD describe the physical form factor of the module. As long as the Ethernet media types are the same (i.e. both ends of the link are 400G-DR4, or 400G-FR4 etc.), OSFP and QSFP-DD modules will interop with each other.

Yes, the 400G-DR4 / XDR4 / PLR4 transceivers can interoperate with each other, with the max distance limited by the shortest reach transceiver.

400G QSFP-DD SR8 Transceivers
400G QSFP-DD SR8 Transceivers
“SR” refers to 100m reach using multi-mode fiber, and “8” implies there are 8 optical channels. Each of the 8 optical channels from an SR8 module are carried on separate fibers, resulting in a total of 16 fibers (8 Tx and 8 Rx). Each optical channel operates at 50Gb/s. The SR8 module uses an MPO-16 APC connector to connect to 8 fiber pairs. The SR8 module can be configured for 400G- SR8, 2x 200G-SR4 and (operating at ½ rate) 2x 100G-SR4.
400G QSFP-DD SR4 Transceivers
400G QSFP-DD SR4 Transceivers
“SR” refers to 50m reach using multimode fiber, and the “4” implies there are 4 optical channels. Each of the 4 optical channels are carried on separate fibers, resulting in a total of 4 pairs of fibers. Each optical channel operates at 100Gb/s. There are two IEEE defined standards for 100G/wave MMF optics: 400GBASE-SR4 (for 100m reach over parallel OM4 MMF), and 400GBASE-VR4 (for 50m reach over parallel OM4 MMF).
400G QSFP-DD DR4, XDR4 and PLR4 Transceivers
400G QSFP-DD DR4, XDR4 and PLR4 Transceivers
“DR” / “XDR” / “LR” refer to 500m / 2km / 10km reach using single-mode fiber, and “4” implies there are 4 optical channels. Each of the 4 optical channels are carried on separate fibers, resulting in a total of 4 pairs of fibers. Each optical channel operates at 100Gb/s. The DR4 / XDR4 / PLR4 modules use the widely deployed MPO-12 APC SMF connector to connect to 4 fiber pairs.
400G QSFP-DD FR4 / LR4 Transceivers
400G QSFP-DD FR4 / LR4 Transceivers
“FR” / “LR” refers to 2km / 10km reach using single-mode fiber, and “4” implies there are 4 optical channels. Unlike the DR4 and SR8, all 4 optical channels from an FR4 / LR4 are multiplexed onto one fiber, resulting in a total of 2 fibers from the module (1 Tx and 1 Rx). Each optical channel operates at 100Gb/s. The modules use a duplex LC optical connector.
JTOPTICS® 400G QSFP-DD Breakout AOC (Active Optical Cable) assemblies include 400G QSFP-DD to 4x 100G QSFP56 breakout AOC. The module integrates eight parallel lanes on 400G end and fan-out to four parallel lanes on each 100G end. Each lane operate 53.125Gb/ps PAM4 modulation signal. These 400G para..
₹ 161,070.00
The Dell 470-AEDF is a versatile 400G to 4x100G Active Optical Cable (AOC) designed for high-performance connectivity in data centers and enterprise networks. This cable features a QSFP-DD (Quad Small Form-Factor Pluggable Double Density) connector on one end and four QSFP28 (Quad Small Form-Factor ..
₹ 161,070.00
JTOPTICS® 400G QSFP-DD to 8x50G SFP56 breakout active optical cables operate over multi-mode fibers (MMF). This breakout cable is compliant with QSFP-DD MSA/SFP28 MSA and IEEE 802.3cd Standards. Thin and lightweight AOC cables simplify cable management, enabling an efficient system airflow, which is..
₹ 163,691.00
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