[ipxe-devel] A problem of DHCP in iPXE (thread id 7603)

[Christian Nilsson]

Hej Jonas,

A few things sticks out,
* guessing half of the packets have a vlan tag, others do not.
* multiple clients (or client mac addresses) in the dump, does the client
have multiple interfaces or is it actually different clients? (can you
provide any other info about the network setup?)
* Do you have logs from the dhcp server, and what kind of dhcp server is it?

All these are Transaction ID 0xc0565e2e
packet 751 is Discover from 05:7a:8d Which gets an offer in 753 for
172.21.10.12
packet 756 is Discover from 05:58:13 Which gets an offer in 758 for
172.21.10.13
packet 761 is Request from 05:7a:8d for 172.21.10.13 Which gets a NAK in
763 (wrong ip<->mac mapping)
packet 766 is Request from 05:58:13 for 172.21.10.13 Which gets a ACK in 768

If this is an iPXE issue it must be due to multiple nics?
My other guess is that a switch has a dhcp relay activated or that there is
some kind of dhcp forwarding going on that sends dhcp packets with a
different source mac?

Regards
Christian


On Mon, Sep 26, 2016 at 5:17 PM, <jonas.granath at soltec.se> wrote:

> Hi,
>
> http://forum.ipxe.org/showthread.php?tid=7603
>
> Now I think I have managed to capture this.
> Filter on bootp.option.dhcp == 6 and you will find the DHCP NAK. I am no
> export on debugging ethernet traffic but as far as I can see the IP address
> in the DHCP offer sent to that mac address does not match the later
> requested IP.
>
> Any help would be greatly appreciated.
>
> /Jonas
>
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>
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