View source for NC-SI

{{Short description|Electrical interface and protocol}}
{{Infobox standardref
| title             = Network Controller Sideband Interface
| status            = Published
| year_started      = {{Start date and age|2010}}
| organization      = [[Distributed Management Task Force]] (DMTF)
| abbreviation      = NC-SI
| base_standards    = [[Platform Management Components Intercommunication]] (PMCI)
| domain            = [[Out-of-band management]]
| website           = {{URL|http://www.dmtf.org/standards/pmci}}
}}
'''NC-SI''', abbreviated from '''network controller sideband interface''', is an electrical interface and protocol defined by the [[Distributed Management Task Force]] (DMTF). The NC-SI enables the connection of a [[baseboard management controller]] (BMC) to one or more [[network interface controller]]s (NICs) in a server computer system for the purpose of enabling [[Out-of-band management|out-of-band]] system management. This allows the BMC to use the network connections of the NIC ports for the management traffic, in addition to the regular host traffic.<ref>OCP Mezzanine card V2.0-1.1 Specification (PDF) in Open Compute Project Server/Mezz [https://www.opencompute.org/wiki/Server/Mezz]</ref><ref>OCP NIC 3.0 Specification 1.00 (PDF) in Open Compute Project Server/Mezz [https://www.opencompute.org/wiki/Server/Mezz]</ref>
The NC-SI defines a control communication protocol between the BMC and NICs.  The NC-SI is supported over several transports and physical interfaces.
== Hardware interface ==
The RMII-based transport (RBT) interface defined by NC-SI is based on the [[Media Independent Interface|RMII]] specification with some modifications that allow connection of multiple network controllers to a single BMC. The NC-SI can also operate over a variety of other electrical interfaces, including [[SMBus]] and [[PCI Express]] when used over the [[Management Component Transport Protocol]] (MCTP).
The table below sums up the signals comprising the RBT interface.
{| class="wikitable"
|-
! Signal !! Description
|-
| REF_CLK || 50 MHz clock reference for receive, transmit and control interface
|-
| CRS_DV || Carrier sense and receive data validity for the traffic sent from one of the NICs
|-
| RXD[1:0] || Receive data (from the NIC to the BMC)
|-
| TX_EN || Transmit enable and data validity for the traffic sent from the BMC
|-
| TXD[1:0] || Transmit data (from the BMC to the NIC)
|-
| RX_ER || Receive error signal, sent from the NIC to the BMC (optional)
|-
| ARB_IN || Input data hardware arbitration (optional)
|-
| ARB_OUT || Output data hardware arbitration (optional)
|}
== Traffic types ==
The NC-SI defines two fundamental types of traffic, pass-through and control traffic. Pass-through traffic consists of data exchanged between the BMC and the network via the NC-SI interface. Control traffic is used to inventory and configure aspects of NIC operation and control the NC-SI interface.
Control traffic is broken down into three sub-types:
* Commands, sent from the BMC to one of the NICs
* Responses, sent by the NICs as results of the commands
* Asynchronous event notifications (AENs), sent asynchronously by the NICs and equivalently to interrupts, upon the occurrence of the specified event
When the NC-SI is used over RBT, standard Ethernet framing is used for all traffic types.  Control traffic is identified by using an [[EtherType]] of 0x88F8. When the NC-SI is used in conjunction with MCTP, MCTP provides the packetization methodology and traffic type identification.
== See also ==
* [[Management Component Transport Protocol]] (MCTP)
* [[Platform Management Components Intercommunication]] (PMCI)
== References ==
{{reflist}}
== External links ==
* [http://www.dmtf.org/ DMTF Homepage]
* [http://www.dmtf.org/sites/default/files/standards/documents/DSP0222_1.1.0.pdf NC-SI Specification rev 1.1.0]
* [https://www.dmtf.org/sites/default/files/standards/documents/DSP0261_1.2.2.pdf NC-SI over MCTP Binding Specification rev 1.2.2]
{{DMTF Standards}}
{{DEFAULTSORT:Nc-Si}}
[[Category:DMTF standards]]
[[Category:Out-of-band management]]