[syslinux] Client-identifier option in PXE search order

[Constantine Gavrilov]

>/> This allows us to bind the UUID to IP, and then pxelinux branches based
/>/> on the IP...
/>/> 
/>
> You can also tell dhcpd to generate an option 209 from the UUID, if you 
> prefer.

It is doable from dhcpd.conf, however when adding a node, one must do:
 * add uuid entry to dhcpd.conf
 * restart dhcp

It is not always desirable (or convinient) when managing multiple nodes. Also, it requires
dhcp server that supports this.

Ideally, for automatic node discovery and following management of discovered node, one would
like to do:

* have simple dhcpd.conf with default boot image of pxelinux.0
* new node boots with pxe, pxelinux.0 is booted and uses default config file
* default ramdisk, NFS (or ISCSI) root image is booted by pxelinux.0
* defalt image reports this new node to "management" (HW params, MAC addrs, UUID)
* "management" sees new node. It is now available for further assignment
* "management" assigns node to some other image. To do so, the pxe file for this node is created
(or changed if node is reassigned).

PXE file naming scheme based on MACs achieves it, except it makes NIC replacement and
working with multiple NICs of the same node tricky. Here, I would wish to use a PXE file
naming scheme based on UUID. This would reduce requirements on DHCP server and would not
require DHCP configuration changes.


	- constg.