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Ethernet QSFP28 Interfaces

The network ports of the ConnectX®-4 adapter card are compliant with the IEEE 802.3 Ethernet standards listed in Features and Benefits. Ethernet traffic is transmitted through the SFP28/QSFP28 connectors on the adapter card.

The adapter card includes special circuits to protect from ESD shocks to the card/server when plugging copper cables.

PCI Express Interface

The ConnectX®-4 adapter card supports PCI Express Gen 3.0 (1.1 and 2.0 compatible) through an x8 or x16 edge connector. The device can be either a master initiating the PCI Express bus operations, or a subordinate responding to PCI bus operations. The following lists PCIe interface features:

Supported PCIe InterfaceFeatures
PCIe Gen 3.0 (1.1 and 2.0 compatible) through x8/x16 edge connectors

Link Rates: 2.5. 5.0 or 8.0GT/s.
Auto Negotiation to: x16, x8, x4, x2 or x1.
Support for MSI/MSI-X mechanisms.

LED Interface

There is one bicolor (Yellow and Green) I/O LED per port to indicate speed and link status. 

Link Indications


Bi-color LED (Yellow/Green) - Link speed

Beacon command for locating the adapter card1Hz blinking Yellow 

4Hz blinking Yellow Indicates an error with the link. The error can be one of the following:

Error Type


LED Behavior


I2C access to the networking ports fails Blinks until error is fixed


Over-current condition of the networking portsBlinks until error is fixed
Link Activity

• A constant Green indicates a link with the maximum networking speed.
• A constant Yellow indicates a link with less than the maximum networking speed.

Link Up

• A constant Green indicates a link with the maximum networking speed.
• A constant Yellow indicates a link with less than the maximum networking speed.

Heatsink Interface

A heatsink is attached to the ConnectX-4 IC in order to dissipate the heat from the ConnectX-4 IC. It is attached either by using four spring-loaded push pins that insert into four mounting holes or by screws.

ConnectX-4 IC has a thermal shutdown safety mechanism that automatically shuts down the ConnectX-4 card in cases of high-temperature event, improper thermal coupling or heatsink removal.

SMBus Interface

ConnectX-4 technology maintains support for manageability through a BMC. ConnectX-4 PCIe stand-up adapter can be connected to a BMC using MCTP over SMBus or MCTP over PCIe protocols as if it is a standard Mellanox PCIe stand-up adapter. For configuring the adapter for the specific manageability solution in use by the server, please contact Mellanox Support.

Voltage Regulators

The voltage regulator power is derived from the PCI Express edge connector 12V supply pins. These voltage supply pins feed on-board regulators that provide the necessary power to the various components on the card.