PXE boot fails with timeout across some vlan switches

  • 3717186
  • 06-Feb-2008
  • 27-Apr-2012

Environment

Novell ZENworks 10 Configuration Management

Situation

Workstation devices on separate segment from ProxyDHCP server timeout during PXE boot. Workstations on the same segment as the ProxyDHCP server work correctly.
SomeVLAN switches will not forward the DHCP response from the ZCM 10 ProxyDHCP server. The workstation times out and boots into the OS.
PXE only works on the local subnet of the Proxy DHCP server.
Packet trace shows incorrect port being used to communicate with DHCP forwarder.

Resolution

This is fixed in version 10.0.3 - see KB 3486285 "Updates to ZENworks 10 Configuration Management" which can be found at https://www.novell.com/support

Additional Information

An incorrect port is being used to communicate with DHCP forwarder.
The DHCP request from the workstations is forwarded to the ProxyDHCP server. The server sends a response back to the switch but the switch doesn't forward the response.

According to RFC 1542, when a BootP Relay Agent is used, the server should respond with a unicast to the IP address of the Relay Agent. The UDP destination port should be set to BootpS (67).

The ProxyDHCP server is using port 68 (BootpC).

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