FW: DHCPREQUEST Problem

Simon Hobson dhcp1 at thehobsons.co.uk
Mon Apr 16 09:11:12 UTC 2007


DESEtech - Germán P. Santillán wrote:
>I have a ISC-DHCP Server v3.0.5 running on FreeBSD 6.2-p3 RELEASE, the
>logical network map is:
>
>DHCP-Server <---> Layer-2 Switch <---> Layer-2 Switch <---> Layer-2 Switch
><---> DHCP-Client.
>
>My DHCP-Client sends a DHCPDISCOVER message and my DHCP-Server answers it
>with a DHCPOFFER, that includes a IP Address of the Pool, but the
>DHCP-Client do not send a DHCPREQUEST message, but other DHCPDISCOVER
>message.
>
>What's wrong?

Have you looked in the list archives ?



Hard to say, but there are two common reasons :

1) The offer did not reach the client. I assume 
you've checked that if you manually configure the 
client then the network works correctly ?

2) The offer is in some way unacceptable to the client.

This is harder to determine as they generally 
don't give you any clue. I once had a printer 
which would not accept an address by DHCP - even 
when I fixed the fact that it didn't request it's 
subnet mask ! I found out a couple of years later 
while looking for something else that it would 
only accept a lease that was longer than 2 years !

First step is to look at the discover packets and 
see what options the client is requesting - then 
see if your server can provide them all. The 
client probably will not need all the options, 
but there may well be some that it requires - for 
example if the client is a bootloader then it 
can't go very far if you don't give it enough 
information to download the image to be booted !

Other than that, try giving us some useful 
information to work with. What is the client ? - 
some clients have known foibles. What is your 
dhcp server config ?


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