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12. Serial Interfaces

12.1 Overview

The SerialInterface resource in Redfish represents a physical serial interface, which may support Serial Over LAN (SOL) for remote interaction with the OOB over a WebSocket connection.

12.2 Schema Summary (v1.2.0)

Field Type Description
Id string Unique identifier of the resource
Name string Display name
ServiceEnabled boolean Enables or disables the entire serial interface service
InterfaceEnabled boolean Enables or disables the specific interface
RedirectionEnabled boolean Enables or disables SOL for the interface
BitRate integer Baud rate (e.g., 115200)
DataBits integer Number of data bits
Parity string Parity setting (None, Even, Odd, etc.)
StopBits string Stop bit configuration (One, Two)
FlowControl string Flow control mode (None, Hardware, XonXoff)
ConnectorType string Connector type (DB9,Proprietary, etc.)
SignalType string Electrical signal type (Rs232, TTL, etc.)
Actions object Available Redfish actions (e.g., Connect for SOL)

12.3 API Endpoints

List Serial Interfaces

Returns a collection of serial interfaces available on the OOB.

URI: /redfish/v1/Managers/BMC/SerialInterfaces

Method: GET

Response:

{
  "@odata.id": "/redfish/v1/Managers/BMC/SerialInterfaces",
  "Members@odata.count": 1,
  "Members": [
    {
      "@odata.id": "/redfish/v1/Managers/BMC/SerialInterfaces/1"
    }
  ]
}

Get a Specific Interface

Returns detailed information about a specific serial interface.

URI: /redfish/v1/Managers/BMC/SerialInterfaces/{id}

Method: GET

Response:

{
    "@odata.id": "/redfish/v1/Managers/BMC/SerialInterfaces/1",
    "Id": "1",
    "Name": "Serial Console",
    "SignalType": "TTL",
    "BitRate": 115200,
    "Parity": "None",
    "StopBits": "1",
    "DataBits": 8,
    "ConnectorType": "Proprietary",
    "ServiceEnabled": true,
    "InterfaceEnabled": true,
    "RedirectionEnabled": true,
    "Actions": {
        "#SerialInterface.Connect": {
            "target": "/redfish/v1/Managers/BMC/SerialInterfaces/1/Actions/SerialInterface.Connect"
        }
    },
    "Links": {
        "ConnectedVia": {
            "@odata.id": "/redfish/v1/Managers/BMC"
        }
    }
}

Update Serial Interface Settings

This API allows modification of specific properties of a serial interface. A common use case is enabling or disabling the Serial Over LAN (SOL) redirection feature by updating the RedirectionEnabled field.

URI: /redfish/v1/Managers/BMC/SerialInterfaces/{id}

Method: PATCH

Example Request to Enable SOL Body:

{
  "RedirectionEnabled": true
}

Example Request to Disable SOL Body:

{
  "RedirectionEnabled": false
}

Response

HTTP Status Code: 204 No Content

If the operation is successful, a status code 204 No Content will be returned. You can also issue a GET request afterward to verify the current value of RedirectionEnabled.

HTTP Status Code: 400 Bad Request

If the provided parameters are incorrect or if the SOL session is currently in use, a 400 Bad Request status code will be returned.

Connect to SOL

Initiates a Serial Over LAN (SOL) session and returns a WebSocket URL for the client.

URI: /redfish/v1/Managers/BMC/SerialInterfaces/{id}/Actions/SerialInterface.Connect

Method: POST

Response

HTTP Status Code: 200
{
  "SerialConnectUri": "wss://<OOB IP>:8443"
}
HTTP Status Code: 400 Bad Request

If RedirectionEnabled is false, a 400 Bad Request status code will be returned.

HTTP Status Code: 409 Conflict

If the SOL session is currently in use, a 409 Conflict status code will be returned.

12.4 SOL (Serial Over LAN) Workflow

The Serial Over LAN (SOL) feature enables remote access to the system’s serial console through a secure WebSocket connection. Below is a step-by-step guide to how the SOL process works using Redfish APIs:

Step 1: Discover Available Serial Interfaces

Use the following endpoint to list all available serial interfaces managed by the OOB: 

GET /redfish/v1/Managers/BMC/SerialInterfaces
This returns a list of interface resources, each with a unique identifier.

Step 2: Check Interface Capabilities and Status

Use the GET method to inspect a specific interface: 

GET /redfish/v1/Managers/BMC/SerialInterfaces/{id}
Ensure the following fields are set appropriately:

  • "ServiceEnabled": true
  • "InterfaceEnabled": true
  • "RedirectionEnabled": true

If any of these fields are set to false, the SOL connection will be disallowed.

Step 3: Initiate the SOL Session

To begin a remote SOL session, issue a POST to the following action: 

POST /redfish/v1/Managers/BMC/SerialInterfaces/{id}/Actions/SerialInterface.Connect
If the interface is available and the settings permit redirection, the OOB responds with the WebSocket URI needed for the SOL session.

Step 4: Establish WebSocket Connection

Use the WSS URI provided in the response to open a secure WebSocket connection.

This WebSocket will transmit and receive data as if it were a local serial connection.

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