[syslinux] pxelinux tftp timeout

[David Halik]

Geert Stappers wrote:
> Op 21-05-2008 om 16:36 schreef H. Peter Anvin:
>> David Halik wrote:
>>> Is there a way to change the default timeout for tftp in pxelinux? The 
>>> be more specific, we use IP in HEX to network boot and it takes a very 
>>> long time for pxelinux to timeout on GUID and MAC, before finally 
>>> getting to HEX and booting.
>> Well, you obviously can't configure it in the configuration file, since 
>> we're talking about how the configuration file is located!  You can send 
>> a DHCP option to give it the name of the configuration file, *however*, 
>> there is something wrong with your TFTP server.  Under normal 
>> circumstances, there is no need to timeout here - the TFTP server should 
>> send back an error reply, and so processing the various nonexistent 
>> filenames should take only a fraction of a second.
> 

Hmm, well that is definitely the symptom. It sits at each wrong guess 
for a couple of minutes before proceeding on and finally getting to the 
correct HEX entry, so according to what you're saying pxelinux is not 
seeing the error response from the tftp server. I'll look into that some 
more.

> FWIW: I think it is not the TFTP server.
> That server is probally missing name server information.
> The long timeout time is name resolving time out.
> 
> 

Actually, this could be the reason! I'm curious, why is dns necessary if 
  the pxeboot transactions are all IP based? DNS in our network is a 
mysterious world because we do a lot of work with private 192 IP space, 
virtual IP's, and load balanced clusters. Effectively, there are many 
instances when a machine's internal IP (the one DHCP gives pxelinux) 
does not have a fully registered hostname, only it's outside vip does, 
and this could represent a whole cluster. What I'm trying to say here is 
that we run a very large network where most servers are initially 
installed or brought up without registered domain names because tftp is 
all done from point to point across 192 by IP. This means DNS lookups 
are not helpful on much of the 192 space by design. Of course, it sounds 
like all I have to do is give the tftp server an entry in /etc/hosts to 
test and see if it fails over correctly. I'll try some of these out and 
see if it changes.


> Cheers
> Geert Stappers
> 
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-- 
================================
David Halik
System Administrator
OIT-CSS Rutgers University
dhalik at jla.rutgers.edu
================================