How to Troubleshoot Self-Electing PXE Services

LANDesk Targeted Multicast Service

The LANDesk Targeted Multicast Service (TMCSVC.exe) is responsible for all PXE Elections.  When a device is elected, the TMC Service running on that device will install both PXE services and will keep all PXE files up to date including boot.wim and netboot files.  It will check for updated files on the core according to the set polling frequency (15 minute default).  TMCSVC.exe uses multicast packets to poll it's subnet.  These packets do not need to leave the subnet so it is usually not necessary to allow multicast traffic on your routers, but any local firewalls, endpoint security or similar products must allow multicast.

PXE Rep Scoring

When determining which device will be elected as the PXE rep, a scoring process takes place.  This is an automatic process that happens in the background.  However, you can influence the score of individual machines by modifying this registry key:

HKLM|SOFTWARE|Wow6432Node|LANDesk|ManagementSuite|WinClient|CSEP

The keys are not there by default so create any missing keys.

Set the PXE_SVC_SCORE dword to a numerical value.  Configuring this reg key will set the starting point used to calculate the score of the device for the PXE Rep election.

The higher you set this value the more likely the device will be elected as the PXE Rep.  A value of 25 is usually sufficient, and 100 will essentially lock that machine in as the PXE Rep.

When is this useful?

PXE Service is giving "Subnet Error"

Reference PXE Service is giving "Subnet Error"

PXE Service is "Crippled"

If the CSEP registry key specified above also contains a "PXE_SVC_CripReason" string, this indicates the PXE Service has determined that it is 'crippled' and is informing CSEP that it cannot act as the PXE Rep.  Common causes for this crippled state would be failure to download the boot.wim or netboot files.

To solve this issue, troubleshoot the failure indicated in the dword.

Multiple NICs or WiFi-only Devices

A device with more than one NIC or a device with only WiFi will not be elected as PXE Rep, even if it scores higher than other devices.

Other Common Issues

• Device is elected, but PXE services will not run?
  • Make sure the Certificate for this device is approved.  Devices without an approved cert may still be elected, but the services will be prevented from running.
    • Pre-SU2 there is no warning or logging about this condition so it is vital to check Client Access on the core and approve certs:
      
    • After SU2 is applied, you will see a message indicating the elected device does not have an approved certificate in Self-Electing PXE Services.  Devices in this condition will be allowed to function as a PXE Rep for one hour.  After the hour expires, a new PXE rep will be elected.

Relevant Log Files

Tmcsvc.log

• C:\ProgramData\LANDesk\Log\tmcsvc.log
• The Targeted Multicast Service on the client handles all elections
• When a device is elected for the first time TMCSVC installs the LANDesk PXE Service and LANDesk PXE MTFTP Service
  
  These services will remain installed, but inactive, if the PXE election changes
• TMCSVC is responsible for starting and stopping the services whenever elections take place

Note: Restarting the LANDesk Targeted Multicast Service on the PXE rep will cause the rep to go through the election process.

SelfElectController.log

• C:\ProgramData\LANDesk\Log\SelfElectController.log
• This log contains more information on elected devices

PXEsvc.log

• C:\ProgramData\LANDesk\Log\pxesvc.log
• Enumerates the PXE Service install process, Boot.wim and Mac NBI download process and communication with the core server

Note: Restarting the LANDesk PXE Service on the PXE rep will cause the rep to attempt to download the boot wim and NBI files.

Pxemtftp.log

• This is not used during the election process but enumerates the file transfer of the boot.wim and NBI files to clients as they perform a network boot.