Thanks for the response, i saw the other thread in the morning. Will use that 
thread, if i have further questions.
-Paddu


 
From: Pasquale Porreca <pasquale.porr...@dektech.com.au>
Reply-To: "OpenStack Development Mailing List (not for usage questions)" 
<openstack-dev@lists.openstack.org>
Date: Wednesday, December 17, 2014 12:37 AM
To: "openstack-dev@lists.openstack.org" <openstack-dev@lists.openstack.org>
Subject: Re: [openstack-dev] [Neutron][Nova][DHCP] Use case of enable_dhcp 
option when creating a network

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 

 
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Pasquale Porreca

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