[mythtv-users] Questions on PXE booting a frontend

[Francesco Peeters]

Gareth Glaccum wrote:
> >from Jelta
> I am surprised that this works. How do you prevent the router from
> assigning
> an IP before your backend does? Or has it just been the luck of the draw,
> and you have been lucky a lot?
> ---
>
> I have the same setup. There is no reliance on luck.
> The PXE client in a machine, CANNOT accept a response from a dhcp
> server which does not specify a valid filename to download (part of
> the specs for PXE).
> If you watch the PXE client, you might see:
>
> Gaining IP information from DHCP: ...-.-...
>
> The . symbols are from each packet/timeout which is not responded to.
> The - symbols are for each response received, which is invalid (i.e.
> no filename).
> If you set up your diskless machine correctly, once it has the kernel
> and initrd, it doesn't matter which DHCP server responds, so long as
> the networking information allows the system to mount a rootfs somehow
> (either NFS server, or ISCSI, or tmpfs/rsync being the more popular
> choices). So basically, you can have a dynamic lease on the router,
> with a non-dynamic lease on the backend, both on the same subnet. The
> PXE can only work with the backend, and once the network is up, the
> machine shouldn't care if it's IP address changes (and it shouldn't
> happen, as most DHCP clients perform re-requests for leases from a
> specified DHCPSERVER [in the initial packet response] and the router
> should not respond to any non-broadcast requests).
>
> Regards,
> Gareth
Correct, I have had the exact same setup at home: a Linux server that
only responds to two specific mac addresses' DHCP requests and a
firewall with a generic DHCP.

I used it for something different than Myth, but it still worked like a
charm!  ;)

BRgds,
-- 
Francesco