Problems DHCP+PXE on 1750

Matt Domsch Matt_Domsch at
Fri Aug 22 00:01:01 CDT 2003

> server, but times out with no reply and returns the the same prompt.
> There is no record of a DHCPREQUEST on the server side (at least not one
> which the DHCP server recognized)

It sounds like you've got (slow) Spanning Tree Protocol enabled on your
switch.  Consider using the Fast STP mode.

I believe that BIOS PXE DHCP request sends a broadcast message, requesting 
a broadcast response, so this makes it through the switch regardless of 
STP mode.

Pump (the DHCP client portion of anaconda, the Red Hat installer), 
requests unicast response.  If this happens before the STP has finished, 
the response is dropped.

> Now the funny thing is that if you just hit return again at this point
> and have the installation script re-query DHCP, the IP data is read from
> the server just fine and the installation continues without problem.

Right, STP has completed by the time the second pump query goes out, so 
the response can come back.

Try changing your switch settings and see if that helps.


Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions
Linux on Dell mailing lists @

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