'invalid subnet mask' configuring IMM in UEFI - IBM System x3200 M3, x3250 M3


RETAIN tip: H21649


When users are configuring IMM subnet mask via Unified Extensible Firmware Interface (UEFI) F1 setup menu, the message 'invalid subnet mask' appears after entering the last octet of the subnet mask if it is greater than 99.

For example, the issue can be observed when performing the following steps:

  1. Enter F1 Setup Menu
  2. Select System settings
  3. Select Integrated Management Module
  4. Select Network Configuration
  5. Select Subnet mask press enter
  6. Enter a subnet mask where the last octet is greater than 99. For example:

Affected configurations

The system may be any of the following IBM servers:

  • System x3200 M3, type 7327, any model
  • System x3200 M3, type 7328, any model
  • System x3250 M3, type 4251, any model
  • System x3250 M3, type 4252, any model
  • System x3250 M3, type 4261, any model

This tip is not software specific.

This tip is not option specific.

The system has the symptom described above.

The following system BIOS/uEFI level(s) are affected:

  • ibm_fw_uefi_gye158a-1.16 and any previous version(s)


The fix has been included in the fourth quarter 2013 Unified Extensible Firmware Interface (UEFI) firmware release.

The file is available by selecting the appropriate Product Group, type of System, Product name, Product machine type, and Operating system on IBM Support's Fix Central web page, at the following URL:


Users can work around the issue by applying the following setup methods:

In IBM Integrated Management Module (IMM) web interface, follow the following steps to change the subnet mask value:

  1. Log on IMM web interface
  2. Click the 'Continue' bottom
  3. Select 'Network Interfaces' in IMM Control section
  4. Update the subnet mask value, for example:
  5. Click the 'Save' bottom in the bottom right corner of the web page
  6. Select 'Restart IMM' in IMM Control section
  7. Click 'Restart' bottom

In the Advanced Settings Utility(ASU), follow the following steps to change the subnet mask value:

  1. Download ASU via IBM Support Fix Central web page, at the following URL:



  2. Open a command (CMD) program.
  3. Direct to the folder 'ASU'
  4. Execute command: 'asu64.exe'
  5. Execute command: 'asu64.exe set IMM.HostIPSubnet1 "SubnetMaskValue" --host IMMHostIP'

      (where: SubnetMaskValue = subnet mask value that users would like to set, for example:; IMMHostIP = IMM host IP address of each system, for example:
  6. Execute command: 'au64.exe show IMM.HostIPSubnet1 --host IMMHostIP' to confirm if the subnet mask value has been saved correctly.
  7. Execute command: 'asu64.exe rebootimm --IMMHostIP'

Applicable countries and regions


Document id:  MIGR-5093548
Last modified:  2014-02-06
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