[Openstack] Kilo Devstack - DCHP is not assigning IPs to the VMs

Neil Jerram neil at tigera.io
Mon Jun 20 08:43:09 UTC 2016


In that case I guess you are somehow missing the iptables rule that fills
in the CHECKSUM properly on DHCP replies.  Is the problem fixed if you add
the following iptables rule in the DHCP namespace on the network node?

iptables -A POSTROUTING -t mangle -p udp --dport 68 -j CHECKSUM
--checksum-fill

    Neil




On Mon, Jun 20, 2016 at 9:30 AM Ahmed Medhat <a.medhat.h at gmail.com> wrote:

> Hi Neil,
>
> Thanks for your reply.
>
> I have done tcpdump on dhcp port of the private network in Openstack and I
> saw the received dhcp request and replies. It seems tgat the replies are
> not received to the VM.
> I want to add tgat if I adjusted the ip manually inside the VM instance ,
> it works fine and I can ping the dhcp ip 11.0.0.2 in my case.
>
> I hope this info shows you where could be the problem I have.
>
> Best regards,
> Ahmed
>
>
> On Monday, June 20, 2016, Neil Jerram <neil at tigera.io> wrote:
>
>> Hi Ahmed,
>>
>> Unfortunately there are many possible reasons - and different ones
>> depending on your setup.
>>
>> I will guess, though, that you're using a default OVS setup, without
>> DVR.  In that case DHCP should be provided by Dnsmasq running on your
>> network node, and I would start by checking for that process and looking at
>> its logs (which could be in /var/log/syslog, /var/log/messages, journalctl,
>> ...) to see if there is any sign of DHCP requests being received, and then
>> whether Dnsmasq sends any DHCP responses.
>>
>> Regards,
>>      Neil
>>
>>
>> On Sat, Jun 18, 2016 at 1:34 PM Ahmed Medhat <a.medhat.h at gmail.com>
>> wrote:
>>
>>> Hi All,
>>>
>>> I have installed kilo devstack and have a problem with dhcp, it is not
>>> assigning IPs to the VMs.
>>> What are the reasons for that ?
>>>
>>> Best regards,
>>> Ahmed
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>>
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