PXE boot loading of boot.wim over MTFTP is slow or not progressing on machines booting with older or legacy network adapters

Products

• Ghost Solution Suite

Issue/Introduction

When using PXE and Ghost Solution Suite, it is noticed that older machines take much longer to download the boot.wim or never completely finish. In one tested scenario, the boot.wim took hours to completely load.

When testing on newer machines/hardware, the boot.wim loads very quickly, usually within seconds.

Environment

Ghost Solution Suite 3.3 RU11 and 3.3.12

Cause

Starting with Ghost Solution Suite 3.3 RU11, MTFTP performance has been improved, and as result, the speed it takes a PXE boot has been improved. The default MTU packet size has also increased in PXE configurations.

MTFTP performance may be configured by changing the Packet Size in the PXE Configuration. By default, the Packet Size is 16kb, but can be set to a value as high as 64k.

Machines using older/legacy network adapters may not support the new default 16kb packet size, causing a major performance hit or issues downloading the boot.wim.

Resolution

MTU/Packet size should be configured to allow older machines to load the boot.wim, but not set too low to cause a performance issue with newer machines/nic adapters.

Start by lowering the default MTU of 16kb to 1024 and test the older machines again. If the boot.wim loads much faster, you can continue increasing this value (x2) to find the optimal packet size for all machines.