The Twin-port transceiver is a key innovation for expanding the 400G NDR InfiniBand Quantum-2 and 400GbE Spectrum-4 Ethernet (400G IB/EN) switch capabilities. The line rate is 400Gb/s for both 400GbE Ethernet and NDR InfiniBand based on the 100G-PAM4 modulation. The switches use Twin port OSFP cages supporting two transceiver engines in a single OSFP form-factor plug creating 800Gb/s electrical to the switch and 2x400G optics using two MPO/-12/APC optical connectors.
Both switches and use the same Twin port, 2x400G OSFP plugs for transceivers, copper DACs and ACCs and are only used in Quantum-2 and Spectrum-4 OSFP air-cooled switches.
Switches maintain separate protocols. The MMS4X00-NM transceiver includes both InfiniBand and Ethernet protocols which is activated depending on the switch protocol the transceiver is inserted into.
The twin-ports enable several unique configurations to connect switches to switches, ConnectX-7 adapters, and BlueField-3 DPUs.
The primary use case for the MMS4X00-NM transceiver is to link multiple switches together at reaches from 100 to 500 meters. Theys can also link to single port 400G OSFP or QSFP112 form-factor transceivers used in ConnectX-7 adapters and/or BlueField-3 DPUs but only up to their 100-meter maximum reach.
The electronics, optics and optical connectors are the same for both single port OSFP and QSFP112 form-factors. Both ConnectX-7 and BlueField-3 devices can be used with Twin port OSFP transceivers at the same time with their respective form-factor type.
Twin port OSFP single mode transceivers remain at 17 Watts for all configurations.
Twin-Port transceivers require ordering two fibers at specific lengths required
Each fiber cable can each be different lengths. Both fibers need to be same type: both straight or both splitters and not mixed.
Both fibers should be the approximately same length to avoid inducing different latency delays in the fibers (4.5ns/meter).
Straight and splitter fibers cannot be used at the same time in Twin port OSFP transceivers.
NVIDIA supplies single mode, crossover, straight fiber cables up to 100-meters straight and 50-meters for splitters that enable linking transceivers directly together. Customers should seek third-party fiber suppliers for reaches beyond 100-meters and calculate optical power link budgets.
The combinations of Twin port 2x400G OSFP, 400G single port OSFP/QSFP112, ConnectX-7 and BlueField-3 all contains both InfiniBand and Ethernet protocols which is activated upon inserting into an InfiniBand or Ethernet switch. This enables one set of cables, transceivers, adapters and DPUs to have multiple uses in a network – especially in DGX systems where low-latency InfiniBand switching may be used for GPU-to-GPU networking and Ethernet switching systems for storage and cluster communication.
The use cases include:
Switch-to-switch at 800Gb/s
This configuration enables transferring 800Gb/s between two switches using one, 17-Watt twin-port, finned-top DR8 transceivers in each switch and two straight, crossover fibers cables (MFP7E30-Nxxx) up to 100-meters for NVIDIA supplied cables or 3rd party supplied fiber cables up to 500-meters including a crossover fiber segment in the link.
Switch-to-two switches at 400Gb/s
The two 400G ports in the first switch Twin port OSFP transceivers can also be routed to two separate switches at 400Gb/s. Additional ports in the second and third transceivers can be then routed to more switches.
