Data Sheet
Ethernet Controller I210 —Interconnects
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3.2 Management Interfaces
The I210 contains three possible interfaces to an external MC.
•SMBus
•NC-SI
• MCTP (over PCIe or SMBus)
3.2.1 SMBus
SMBus is an optional interface for pass-through and/or configuration traffic between an external MC
and the I210. The SMBus channel behavior and the commands used to configure or read status from
the I210 are described in Section 10.5.
The I210 also enables reporting and controlling the device using the MCTP protocol over SMBus. The
MCTP interface is used by the MC to control the NIC and for pass through traffic. For additional
information, refer to Section 10.7.
3.2.1.1 Channel Behavior
The SMBus specification defines a maximum frequency of 100 KHz. However, when acting as a slave,
the I210 can receive transaction with a clock running at up to 1 MHz. When acting as a master, it can
toggle the clock at 100 Khz, 400 Khz or 1 MHz. The speed used is set by the SMBus Connection Speed
field in the SMBus Notification Timeout and Flags Flash word (Section 6.7.3.3).
3.2.2 NC-SI
The NC-SI interface in the I210 is a connection to an external MC defined by the DMTF NC-SI protocol.
It operates as a single interface with an external MC, where all traffic between the I210 and the MC
flows through the interface.
The I210 supports the standard DMTF NC-SI protocol for both pass-through and control traffic as
defined in Section 10.6.
3.2.2.1 Electrical Characteristics
The I210 complies with the electrical characteristics defined in the NC-SI specification.
The I210 NC-SI behavior is configured on power-up in the following manner:
•The Multi-Drop NC-SI Flash bit (refer to Section 6.7.1.3) defines the NC-SI topology (point-to-point
or multi-drop; the default is multi-drop).
The I210 dynamically drives its NC-SI output signals (NC-SI_DV and NC-SI_RX) as required by the
sideband protocol:
• On power-up, the I210 floats the NC-SI outputs.
• If the I210 operates in point-to-point mode, then the I210 starts driving the NC-SI outputs some
time following power-up.
• If the I210 operates in a multi-drop mode, the I210 drives the NC-SI outputs as configured by the
MC.