Open Stack

Hi quantum developers,

With the current implementation of Qunatum DHCP,
subnet-delete fails just after subnet-create.

Just after a subnet is created dhcp-agent detects the creation of the subnet
and create a port for the subnet. When I try to delete the subnet, the port
created by dhcp-agent is still using the IP address of the subnet, so
subnet-delete will fail.

To address the above, one possible solution is:
when subnet-delete, quantum plugin notifies dhcp-agent to stop the dhcp
server and delete the related quantum port when subnet-delete.
Now the plugin can delete the subnet successfully.

I prefer it since the behaviors of subnet-create and subnet-delete are
symmetric and this scheme can be applied to other system agents (iptables
manager?).


In addition, i think we need a way to distinguish ports for system (such as
dhcp-agnet) from ports used by instances. For example, when subnet-delete
we first check whether ip addresses are used by instances and request
dhcp-agent to remove the port if no instances are connected.

# I have not filed a bug or a BP since I don't know the current status and
# direction of dhcp-agent with RPC and it might have been considered.

Thanks,
-- 
Akihiro MOTOKI <motoki at da.jp.nec.com>
Cloud System Research Laboratories, NEC Corporation