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.
http://lists.openstack.org/pipermail/openstack-dev/2014-December/053069.html 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 > OpenStackfirstname.lastname@example.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
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