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Troubleshooting › PXE-32: TFTP Open Time-out

PXE-32: TFTP Open Time-out

Symptom:

OS installation fails immediately after completing the DHCP or PXE phase with an error message "PXE-32: TFTP open time-out" at the target computer. This problem occurs if the network did not support the packet size requested by the PXE firmware on the target or the MTU size is reduced due to tunneling. IP packets exceeding the MTU size of the network are transmitted in several fragments. Fragmentation is handled by the network layer and typically transparent to the application. Some PXE firmware implementations and also the TFTP client used in DOS boot images do not support fragmentation. Therefore, the effective packet size must be restricted by the boot server in those cases.

Windows PE based boot images can handle fragmentation and as a rule are not affected by a reduction of the MTU size.

Solution:

Restrict the effective TFTP blocksize used by the boot server using the configuration policy.

Note: From Release 12.5, the OSIM target program, sdmpcimg, used by Windows PE boot images requests specific TFTP packets, which are not affected by the configuration parameter TFTP blocksize limit. The parameter TFTP specific blocksize limit can be used to limit the effective blocksize for specific TFTP packets. For more information, see sdmpcimg Command (32bit and 64bit Version).

To restrict the TFTP blocksize

  1. Open the configuration policy that is assigned to the boot server.
  2. Navigate to DSM, Scalability Server, OSIM, ManagedPC, Server, and change the TFTP blocksize limit to a suitable value. For example, if the firmware requests 1456 TFTP data bytes, it may be sufficient to set the TFTP blocksize limit to 1350.

    Note: DOS boot images and CA ITCM r11.x or r12 Windows PE boot images do not support a TFTP blocksize < 1024.

Deployment of Red Hat Enterprise Linux 5 Update 5 OS Fails

Symptom:

In OS Installation Management, when I deploy Red Hat Enterprise Linux 5 Update 5 with an Image created using CDs media, OS installation fails with the following error:
Red Hat Installation tree in that directory does not match your boot media.

Solution:

Do the following:

OSIM Samba Shares not Enabled during Boot Server Installation

Symptom:

Sometimes OSIM Samba shares are not enabled on Linux Operating system even the option "Disable use of windows network shares" is deselected during the installation.

Solution:

Use the following commands to enable Samba shares after the boot server installation:

Unattended Installation of SLES 11SP01 with DHCP

Symptom:

When I configure an unattended install of SLES 11SP01 to use DHCP address allocation without an explicitly stated domain name entry in the autoinst.xml file, then the installer discards any supplied host name and selects a randomly generated hostname, similar to linux-6dyj.

Solution:

To allow for a fixed hostname with the DHCP assigned address, modify the OS image-specific autoinst.xml file to include a default domain in the networking/dns section, as follows:

<networking>
  <dns>
    <dhcp_hostname config:type="boolean" >false</dhcp_hostname>
    <dhcp_resolv config:type="boolean" >true</dhcp_resolv>
    <hostname>$HostName$</hostname>
    <domain>forward.inc.local</domain>
  </dns>
</networking>

You can find the autoinst.xml file at the following location:
DSM_Install_Folder\server\SDBS\var\managedpc\images\IMAGE_NAME\IMAGE_NAME\suse

Change the Configuration to Suit the Microsoft NSF Server

OSIM requires that the boot server hosting XenServer installation files must be exported through NFS services. Based on the OS version, change the configuration to suit the NSF server when the boot server is running on the Microsoft Windows Server.