[syslinux] pxelinux tries to load ldlinux.c32 from DHCP server, instead of next-server

Spike White spikewhitetx at gmail.com
Mon Sep 14 14:02:17 PDT 2015


I think you're right.  I'm looking at the various DHCP configurations that
were tested and work.  Versus the ones that don't work.

We're using a textual presentation of an IP address in DHCP option 66.  Not
a FQDN,

We are passing DNS1 and DNS2 server via DHCP option 6.  So -- PXE BIOS
cannot do DNS lookups?

Spike

On Mon, Sep 14, 2015 at 11:55 AM, Spike White <spikewhitetx at gmail.com>
wrote:

> >On Sat, Sep 12, 2015 at 6:37 PM, Gene Cumm <gene.cumm at gmail.com> wrote:
> >>
> >...
> >
> >> Something like this would be preferable except it's not quite so
> >> simple.  We'd need to not store BOOTP siaddr before parsing.  Store a
> >> pointer to the string during parsing if serverip is unset.  After all
> >> parsing, if the pointer is set, attempt to resolve then set serverip.
> >> Last, if serverip is not set, copy siaddr to serverip.
> >
> >Perhaps a more important question is if ANY PXE implementation uses
> >DHCP option 66 over BOOTP field siaddr.
> >
> >--
> >-Gene
>
> Gene,
>
> Using DHCP option 66 is more maintainable than BOOTP field siaddr in a
> large enterprise PXE deployment scheme.
>
> In DHCP option 66,  you can use either a FQDN or a (textual representation
> of) an IP address.
>
> Using FQDNs is what simplifies migration (& thus, what enterprise sysadmins
> would prefer).  Here's why.  Regardless of which way I go, I have to put
> in a DNS change request.
>
> I'll have to put in the DNS change request anyway, because I'm pointing my
> FQDN to a new IP address.  Even if I decomm the old server and stand up a
> new
> server with a new FQDN, still the old name will be a DNS PTR record
> pointing to the new name. Because the user community knows the old name.
>
> Using FQDNs, when I migrate my TFTP server to a new IP address, now I
> have to put in just one DNS request.
>
> If I use BOOT field siaddr (or textual representation of IP address in DHCP
> option 66), I have to put in two change requests that have to occur
> simultaneously.
>
> One change request to DHCP server maintainer, to change DHCP options.  One
> request to DNS team.  To change A record to new IP address, or to convert
> old FQDN to a PTR record pointing to new server name.
>
> So yes, many PXE implementations prefer DHCP option 66 -- when it works.
>
> Spike
>
>


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