[Openstack-operators] Experimenting with DHCP Agent redundancy

Alvise Dorigo alvise.dorigo at pd.infn.it
Sat Mar 22 09:40:04 UTC 2014


Hi,
it seems to work.
And it seems that when one create a new network/subnet, it is automatically added with a static bind to the existing L3 agent. Then it must be unbounded and rebounded to it and to any other L3 agent.

Can this be considerable as a normal behaviour ? or is it a bug ?

	A.

On 12 Mar 2014, at 11:32, Alvise Dorigo <alvise.dorigo at pd.infn.it> wrote:

> 
> On Mar 12, 2014, at 11:22 AM, Li Ma wrote:
> 
>> Hi,
>> 
>> The binding of network and dhcp-agent seems static. You need to run:
>> # neutron dhcp-agent-network-remove
>> and then,
>> # neutron dhcp-agent-network-add
> 
> I'm not sure to understand.
> Should I remove the net "interna" from the dhcp agents, and then re-add them to both agents ? and then try again to disable the first agent and start a VM ?
> 
> 	A.
> 
>> 
>> -- 
>> ---
>> cheers,
>> Li Ma
>> 
>> 
>> 
>> On 3/12/2014 5:42 PM, Alvise Dorigo wrote:
>>> Hi,
>>> I've installed 2 Network nodes running only neutron agents (the neutron server is located in the controller node).
>>> I see this:
>>> 
>>> # neutron agent-list
>>> +--------------------------------------+--------------------+-----------------------------+-------+----------------+
>>> | id                                   | agent_type         | host                        | alive | admin_state_up |
>>> +--------------------------------------+--------------------+-----------------------------+-------+----------------+
>>> | 215324e6-f19a-41ce-b967-40089388f9ed | Open vSwitch agent | network-02.cloud.pd.infn.it | :-)   | True           |
>>> | 55d8c998-2557-4cac-abbc-4a85d9f190a0 | DHCP agent         | network-01.cloud.pd.infn.it | :-)   | True           |
>>> | 5c03007b-6b02-4260-9f5c-7f1e951cf1b0 | Open vSwitch agent | compute.cloud.pd.infn.it    | :-)   | True           |
>>> | 97ec9951-5c7b-45e0-9de6-40d4efeccd6b | L3 agent           | network-01.cloud.pd.infn.it | :-)   | True           |
>>> | c96ab5a0-2ef4-4f44-90bb-686bbaef4f55 | DHCP agent         | network-02.cloud.pd.infn.it | :-)   | True           |
>>> | cbe4e6bc-0dda-46df-b170-93f6d324a0a5 | Open vSwitch agent | network-01.cloud.pd.infn.it | :-)   | True           |
>>> | dedc11e7-c1c5-4db3-be90-d218f210a00a | L3 agent           | network-02.cloud.pd.infn.it | :-)   | True           |
>>> +--------------------------------------+--------------------+-----------------------------+-------+----------------+
>>> 
>>> I've created 2 networks (one is external -"esterna"-, the other one is not - "interna"-):
>>> 
>>> # neutron net-list
>>> +--------------------------------------+---------+------------------------------------------------------+
>>> | id                                   | name    | subnets                                              |
>>> +--------------------------------------+---------+------------------------------------------------------+
>>> | 6cd46839-c434-42e2-9b9e-a3b2a7fae470 | esterna | 08c33f86-c34a-4fa3-8295-5f9866d9527d 192.135.16.0/24 |
>>> | e1cd28e4-83da-4dc8-bae8-f50600baeff9 | interna | 7ec2317c-40c5-4daf-9997-1242fd4f78b0 192.168.70.0/24 |
>>> +--------------------------------------+---------+------------------------------------------------------+
>>> 
>>> I've added the net "interna" to both dhcp-agents:
>>> 
>>> # neutron dhcp-agent-list-hosting-net interna
>>> +--------------------------------------+-----------------------------+----------------+-------+
>>> | id                                   | host                        | admin_state_up | alive |
>>> +--------------------------------------+-----------------------------+----------------+-------+
>>> | 55d8c998-2557-4cac-abbc-4a85d9f190a0 | network-01.cloud.pd.infn.it | True           | :-)   |
>>> | c96ab5a0-2ef4-4f44-90bb-686bbaef4f55 | network-02.cloud.pd.infn.it | True           | :-)   |
>>> +--------------------------------------+-----------------------------+----------------+-------+
>>> 
>>> VM creation goes smoothly well (I'm using the cirros 0.3.1).
>>> 
>>> Now, if I disable one of the two dhcp agents (using the command "neutron agent-update 55d8c998-2557-4cac-abbc-4a85d9f190a0 --admin_state_up=false") I'd expect that the second dhcp agent can take care of the (new) VMs asking for dhcp address... 
>>> I disabled the first (network-01) dhcp agent.
>>> If I create a new VM it will never get its IP address. So it seems to me that the second dhcp agent (running on network-02) is not actually doing its job... 
>>> If I re-enable the first dhcp agent, new VMs get their IPs.
>>> 
>>> What could I have missed in the procedure ?
>>> 
>>> thanks,
>>> 
>>> Alvise
>>> 
>>> 
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>>> OpenStack-operators at lists.openstack.org
>>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-operators
>> 
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