#!ipxe

goto start

# Warning: Spaghetti code #

:ipxeUpgrade
chain http://myserver/ipxe/superipxe.pxe || goto failed

:start
vcreate --tag 100 && echo VLAN 100 interface online ||
iseq ${builtin/errno} 0x2e022001 && goto ipxeUpgrade ||
goto end

:failed
echo Something failed.  Oh well.
reboot

:end
# And here... whatever you do normally!