[openstack-dev] [Neutron][Nova][DHCP] Use case of enable_dhcp option when creating a network

Pasquale Porreca pasquale.porreca at dektech.com.au
Wed Dec 17 08:37:38 UTC 2014

Just yesterday I asked a similar question on ML, this is the answer I got:

In Neutron IP address management and distribution are separated concepts.
IP addresses are assigned to ports even when DHCP is disabled. That IP
address is indeed used to configure anti-spoofing rules and security groups.


On 12/17/14 09:15, Padmanabhan Krishnan wrote:
> Hello,
> I have a question regarding the enable_dhcp option when creating a
> network.
> When a VM is attached to  a network where enable_dhcp is False, I
> understand that the DHCP namespace is not created for the network and
> the VM does not get any IP address after it boots up and sends a DHCP
> Discover.
> But, I also see that the Neutron port is filled with the fixed IP
> value from the network pool even though there's no DHCP associated
> with the subnet. 
> So, for such VM's, does one need to statically configure the IP
> address with whatever Neutron has allocated from the pool?
> What exactly is the use case of the above? 
> I do understand that for providing public network access to VM's, an
> external network is generally created with enable-dhcp option set to
> False. Is it only for this purpose?
> I was thinking of a case of external/provider DHCP servers from where
> VM's can get their IP addresses and when one does not want to use L3
> agent/DVR. In such cases, one may want to disable DHCP when creating
> networks.  Isn't this a use-case?
> Appreciate any response or corrections with my above understanding.
> Thanks,
> Paddu 
> _______________________________________________
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev

Pasquale Porreca

DEK Technologies
Via dei Castelli Romani, 22
00040 Pomezia (Roma)

Mobile +39 3394823805
Skype paskporr

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20141217/4535e0cf/attachment.html>

More information about the OpenStack-dev mailing list