Overview

The ConnectX-8 adapter is a PCIe Gen 6 bus adapter with an IC that converts 48 lanes of 64GT/s PCIe channels, modulation, and line rates to 4-channels of 200G-PAM4 for 800Gb/s XDR InfiniBand.

ConnectX-8 PCIe adapters cages use the 800G XDR 4-channel (4x200G-PAM4) transceiver and use the RHS format as the heat sinks are riding on top of the ConnectX-8 OSFP card cages and is exposed to system fan airflow. Used to connect GPU/CPU servers and storage to the QM3200 switches. For liquid cooled ConnectX-8 cards, the same RHS transceiver is used.

MPO Optical Connectors are Multiple Push-On 12-fiber, Angled Polished Connector or MPO-12/APC. Two MPO-12/APC optical connectors are used per 2x800G transceiver. The MPO-12/APC connector uses 8-fibers in the Angled Polished Connector (APC) with an 8-degree polish on the fiber end that deflects laser back reflections in the fiber/connector combination from corrupting the optical signals. The transceivers use four transmission (Tx) fibers and 4 receive (Rx) fibers and 4 positions in the connector block are not used for fibers and left blank. These optical connectors are the same type used for NDR.

Optical Fibers and Cables consist of the 9-um, OS1, single mode fiber type. NVIDIA manufactures straight crossover, type-B, 4-channel MPO-12/APC fiber cables in lengths from 1-to-500-meters. A 1:2 splitter fiber is also offered enabling four transceivers to be linked to the 2x800G transceiver with reaches from 1-50-meters. Crossover fiber cables are used to connect two transceivers directly together and aligning (crossing over) the transmit laser in one transceiver to the receive photodetectors in the second transceiver. Same fiber cables are used for NDR.

The Twin-ports enable several unique configurations to connect switches-to-switches at 2x800Gb/s or to two or four network adapters at 800Gb/s using two straight or 1:2 splitter fiber cables.

Using 1:2 fiber splitter cables in each of the two ports in the Twin-port OSFP, up to four RHS flat top single port transceivers can be configured with ConnectX-8 adapters at 800Gb/s each. This configuration uses two fibers per optical connector at 200G-PAM4 rate into the 800G transceivers to achieve 400Gb/s and are considered XDR400 rates, not NDR (4x100G-PAM4).

The 2x800G transceiver in the QM3400 72-cage switch can link at 1600G to the QM3200 switch which offers 36 cages of 1600G or 72 ports of 800Gb/s. These cages also support the NDR family of cables and transceivers for backwards compatibility to NDR (4x100G-PAM4) and HDR (4x50G-PAM4).

Switch-to-Dual 800G ConnectX-8

The Twin port OSFP in the QM3400 and QM3200 switches use two, 4-channel MPO-12/APC optical connectors with two, straight 4-channel fiber cables. Each fiber cable can link to single port 800Gb/ s OSFP RHS form-factor transceiver (NVIDIA part #: 980-9IAT0-00XM00) in two ConnectX-8 adapters.

Switch-to-Quad 400G ConnectX-8

The Twin port OSFP using two, 1:2 splitter fiber cables create four, 2x200G-PAM4 links or 400G a.k.a XDR400. Each 2-fiber cable connector can link to single port 800Gb/s OSFP RHS form-factor transceiver in four ConnectX-8 adapters. The 400G rate is achieved by using only 2-fibers at 200G- PAM4 in the 1:2 fiber cable ends into an 800G transceiver and are considered XDR400 rates - not

400G NDR which is 4x100G-PAM4. Power consumption is also reduced in the 800G transceivers. Separate XDR400G transceivers are not offered.