Cisco Support Community
Community Member

Unable to get TFTP option to work for PXE devices

We are in the process of deplyiing SCCM 2012.

During the PXE boot process, the PXE device (connected to vlan21) gets an IP address from the DHCP server (vlan 21) and is then meant to pick up TFTP image from TFTP server(vlan 21). DHCP Server & TFTP server reside in the same subnet i.e.vlan 21.

For PXE devices connected to the same subnet, the process works fine where it gets an IP address from DHCP & picks up the boot file from the TFTP server and goes through the build process. However, when the PXE device is connected to another VLAN (eg vlan 27), it gets the DHCP IP from DHCP server (vlan 21) but doesn't get the boot file from TFTP server(vlan 21). IP Helper is configured on vlan 27 pointing to DHCP server & TFTP server.

IP Helper configuration has been swapped around on the vlan27 eg from DHCP/TFTP to TFTP/DHCP. However, it doesn't make a difference.

As per the wireshark logs, we can see the TFTP request from PXE device(vlan 21) reaching the TFTP server (vlan 21) from PXE device & can see TFTP server forwarding Block 0 & Block 1. PXE device acknowledges the TFTP Block 0 but then doesn't acknowledge Block 1 (no respone from PXE device to TFTP) and eventually fails to get the TFTP image.

TFTP server & DHCP server are both guests running on a virtual host.

Is anyone able to guide me on the next steps to troubleshoot the PXE device to pick up TFTP boot image from TFTP server.

Hall of Fame Super Gold

My first suggestion would be

My first suggestion would be to check the scopes on the TFTP server. If you are experiencing problems when the devices are in vlan 27 then it is obviously a different scope in TFTP than vlan 21. So can you check and verify that the scope configured for vlan 27 is exactly like the scope configured for vlan 21 (especially for the options used by PXE).


If that does not help then my second suggestion is that you post the configuration of the switch where the vlans are located.





CreatePlease to create content