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Network Controller Sideband Interface
Year started2010
OrganizationDistributed Management Task Force (DMTF)
Base standardsPlatform Management Components Intercommunication (PMCI)
DomainOut-of-band management

NC-SI ("Network Controller Sideband Interface") is an electrical interface and protocol defined by the Distributed Management Task Force (DMTF), which enables the connection of a Baseboard Management Controller (BMC) to a set of Network Interface Controller (NICs) in server computer systems for the purpose of enabling out-of-band remote manageability.

Hardware interface[edit]

The NC-SI interface is based on the RMII interface with some modifications allowing connection of multiple network controllers to a single BMC. It contains the following signals:

Signal Description
REF_CLK A 50 MHz clock reference for receive, transmit, and control interface
CRS_DV Carrier Sense/Receive Data Valid for traffic sent from one of the NCs
RXD[1:0] Receive Data (from NC to BMC)
TX_EN Transmit Enable - Data Valid for traffic sent from the BMC
TXD[1:0] Transmit Data (from BMC to NC)
RX_ER Receive Error
ARB_IN Hardware Arbitration ring - input
ARB_OUT Hardware Arbitration ring - output

Traffic types[edit]

NC-SI traffic can be either pass-through or control traffic, with both traffic types in form of Ethernet frames. Pass-through traffic consists of data exchanged between the BMC and the network via the NC-SI interface. Control traffic includes frames used to configure and control of the NC-SI interface and is identified by an EtherType of 0x88F8.

There are three types of control packets:

  • Commands, sent from the BMC to one of the NCs.
  • Responses, sent by the NCs as results of the commands.
  • AENs (Asynchronous Events Notifications), sent asynchronously by the NCs, equivalent to interrupts.

See also[edit]

External links[edit]