Differences

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--- settings [2013/08/23 11:43]
mcb30
+++ settings [2015/11/05 14:46]
mcb30
@@ Line 86: / Line 86: @@
     net0: 192.168.0.100/255.255.255.0
+===== Advanced topics =====
+==== PXE NBPs ====
+PXE NBPs such as Windows Deployment Service's ''wdsnbp.com'' or ''pxelinux.0'' will attempt to retrieve the contents of the various DHCP packets used by iPXE (via the ''PXENV_GET_CACHED_INFO'' API call).  For example, ''wdsnbp.com'' will examine these DHCP packets to determine which TFTP server address to use.
+There are three packets that may be requested by the PXE NBP: ''DHCPDISCOVER'', ''DHCPACK'' and ''BINL''.  iPXE will construct packets for the PXE NBP based on a combination of the actual DHCP packets and settings provided by other means (such as the ''[[:cmd:set]]'' command).
+The scoping rules for the PXE NBP packets are slightly different from the logical hierarchy of settings scopes used within iPXE:
+  * For the DHCPACK packet, any settings within the network device scope (e.g. ''netX/next-server'') will override any top-level settings (e.g. ''next-server'').
+  * For the BINL packet, any settings present in the ProxyDHCPACK (e.g. ''proxydhcp/next-server'') or in the Boot Server Reply (e.g. ''pxebs/next-server'') will override any top-level settings (e.g. ''next-server'').
+If you need to manually pass specific settings to a PXE NBP, then in most cases you should set these within the network device scope.  For example, to manually set the TFTP server address and path used by ''wdsnbp.com'', you could use:
+    set netX/next-server 192.168.1.2
+    set netX/filename boot\x86\wdsnbp.com
+    chain tftp://192.168.1.2/boot/x86/wdsnbp.com