[syslinux] RIS and PXELINUX

[Mark Dieterich]

Thanks for the reply.

> What DHCP server do you use?

We are running a stock Redhat 7.2 DHCP server (dhcp-2.0pl5-8).

> The TFTP request is a unicast, not a broadcast.  The PXE stack will 
> download from whereever it is requested.  This probably means the RIS 
> server is answering the DHCP request, or possibly the followon 
> pseudo-DHCP request to port 4011 which is part of the PXE protocol.  The 
> latter is usually unicasted, but can be multicasted if the original DHCP 
> reply contained the appropriate magic.

The RIS server does not actually run DHCP.  All of our windows clients
actually obtain their addresses from the linux DHCP server.  I have to admit,
I don't know where the magic is that let's RIS work at all!  As you suggested,
I suspect the RIS server is answering the followup request to port 4011.
I would have thought that the DHCP server option, next-server, would have
overridden this default for the linux boxes we are trying to use PXE with.

> A good question is perhaps: what do you expect to be keeping them apart? 

I'm hoping we can keep them separate through the DHCP conf file.  All of our
hosts are statically assigned in the DHCP tables and I was hoping to use
the group options to apply different parameters to the different groups of
host; perhaps this isn't possible?

>    Unlike the Solaris case there isn't a hardware difference to cue off 
> the servers.  If you have a list of hosts, for example, that is RIS vs. 
> PXELINUX, make sure that *all* DHCP servers (including RIS, if 
> applicable) respect it and don't answer requests not directed to it.  If 
> RIS is set up to answer all requests with a "PXEClient" tag, then RIS is 
> going to run on all PC machines.

Here are the pertinent pieces of the DHCP conf file (excluding all of the
static declarations):

#
# Our domain name
#
option domain-name "cs.brown.edu";

#
# Default time for a lease (in seconds).  36000 = 10 hours
#
default-lease-time 36000;

#
# Max time for lease (in seconds).  If a client requests a longer
# lease than usual, let them have it if less than 1 day.
#
max-lease-time 86400;

#
# Fully Automated Install (FAI) - debian unattended install options
#
#       option-170 is FAI_LOCATION, target is /usr/local/share/fai
#               - this is the custom portion of the install
option option-170 "server:/fai";
option option-171 "install";
option option-172 "createvt sshd";

#
# For PXELINUX clients
#
allow booting;
allow bootp;

group {
    next-server server;
    filename "pxelinux.0";

    host grendel {
        hardware ethernet 00:00:00:00:00:00;
        fixed-address client;
    }
}

group {
    ... static assignments for the non-linux PXE clients ...
}


Thanks,

Mark