[Openstack-operators] Experimenting with DHCP Agent redundancy

Alvise Dorigo alvise.dorigo at pd.infn.it
Wed Mar 12 10:32:08 UTC 2014


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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> 
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