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Level 7

TFTP Server Increase Block Size

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There does not seem to be an option within the GUI in order to change the block size.  Does anyone know if it is possible to do this?

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Some PXE servers have an option to set the TFTP block size - you might look there as well.

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Level 13

The latest version of the SolarWinds TFTP Server supports the blocksize option, which is client-initiated.  That is, the TFTP client requests a file transfer using a specified block size, and the server responds with either an acknowledgement of the requested block size or an error packet with a known error value indicating block size negotiation failure.  So, the TFTP server doesn't really have the option to configure the block size, since the clients request a specific block size.

Can you help me understand what you're attempting to accomplish?  Why do you want to change the block size?

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Many thanks for this information, I am using SolarWinds TFTP Server to operate a PXE service sending out a 180MB Windows PE image.  This works without problem however despite operating on a high speed LAN it is taking around 12 minutes to send the image from the TFTP server to the client, when copying the image manually between SMB shares it takes around 10 seconds.  I read that expanding the TFTP block size to a higher figure can greatly improve PXE booting with lare Windows PE images.

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The block size used by a TFTP transfer is client-initiated.  In your particular case, the PXE-booted machine is the TFTP client, requesting a file (the Windows PE image) from the SolarWinds TFTP Server.  Since the block size option is client-initated, and the PXE-booted machine is the TFTP client, you would need to look for a TFTP block size option and set it appropriately on each of your PXE-booted machines.

Hope this helps!

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Something else to keep in mind: TFTP is an inherently slow protocol.  It was not designed to quickly transfer large files.  TFTP's design goal was to be trivial to implement (TFTP = Trivial File Transfer Protocol) so that it could be implemented in devices (routers, switches, BIOS firmware) where there is little processing power or memory space available.

SMB file transfers, on the other hand, are better-suited for handling large files.  Obviously, that doesn't help in your PXE boot scenario, but I'm mentioning this to make sure that your expectations aren't too high.  You're not likely to modify the TFTP block size alone and achieve the same type of speed that you would get from a SMB file transfer.

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Many thanks for this information, as clients connecting to the PXE server have empty hard drives the only settings to change block size would be in the BIOS of the client which does not seem to have a setting for this.  The clients seem to have a BIOS setting of enable PXE boot and nothing additional.  Thank you for your info I will have to live with the 12 minutes for loading Windows PE images. 

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Some PXE servers have an option to set the TFTP block size - you might look there as well.

View solution in original post

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