Cisco UCS C Series CIMC Error: “Net mode is invalid. Please Select a valid configuration.”

I’ve been asked several times in the past week about the error Net mode is invalid. Please Select a valid configuration message when configuring a Cisco UCS C series server’s CIMC management network traverse through the dedicated port. While the following may not cover all the scenarios, I hope this information is able to help to someone who encounters the same situation:

Before I begin with the problem and explanation, let’s start off with a little bit of background information as to what the options in the CIMC configuration means:

Background Information (from the manual)

http://www.cisco.com/en/US/docs/unified_computing/ucs/c/sw/gui/config/guide/1.2.1/Cisco_UCS_C-Series_Servers_Integrated_Management_Controller_Configuration_Guide_1_2_1_chapter8.html

Server NICs

Two NIC modes are available for connection to the CIMC. In one mode, you can also choose an active-active or active-standby redundancy mode, depending on your platform.

NIC Mode

The NIC Mode drop-down list in the NIC Properties area determines which ports can reach the CIMC. The following mode options are available, depending on your platform:

• Cisco Card—A connection to the CIMC is available through an installed adapter card.

• Dedicated—A connection to the CIMC is available through the management Ethernet port or ports.

• Shared LOM—A connection to the CIMC is available only through the LAN On Motherboard (LOM) Ethernet host ports. In some platforms, a 10 Gigabit Ethernet LOM option is available.

  
  Note

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  In shared LOM mode, all host ports must belong to the same subnet.

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• Shipping (if supported)—A connection to the CIMC is available through the management Ethernet port or ports using a limited factory default configuration.

  
  Note

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  Shipping mode is intended only for your initial connection to the CIMC. Configure another mode for operation.

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NIC Redundancy

The NIC Redundancy drop-down list in the NIC Properties area determines how NIC redundancy is handled:

• None—Redundancy is not available.

• Active-Active—All Ethernet ports operate simultaneously. This mode provides multiple paths to the CIMC.

• Active-Standby—One port fails over to the other.

The available redundancy modes vary depending on the selected network mode and your platform. For the available modes, see the server installation and service guide for your server. This guide is available from the Cisco UCS C-Series Servers Documentation Roadmap at http://www.cisco.com/go/unifiedcomputing/c-series-doc.

Problem

You’re in the Cisco CIMC Configuration Utility to configure the out-of-band access for the Cisco UCS C series servers (I’m using a UCS C210 M2 in this example) but once you hit the F10 button to save, you receive the error:

Net Mode is invalid. Please Select a valid configuration

Problem Explanation

Though there are a few combinations in the configuration that may cause this error message to be thrown, one of the reasons why is if you have the following configuration:

NIC mode: Dedicated

NIC redundancy: Active-standby

OR

NIC mode: Dedicated

NIC redundancy: Active-active

The reason why the error message: Net Mode is invalid. Please Select a valid configuration is thrown is because the Cisco UCS C series server only has one port at the back that is available for the NIC mode: Dedicated.

As shown in the screenshot above, if you want to use the onboard NIC port for CIMC, you will need to set the settings with CIMC as follows:

NIC mode: Dedicated

NIC redundancy: None

Once you’ve completed the changes, hit F10 and you will now see a message indicating the changes will appear after 45 seconds.