[openstack-dev] [neutron][taas] neutron ovs-agent deletes taas flows

Anna Kamyshnikova akamyshnikova at mirantis.com
Wed Dec 16 07:43:01 UTC 2015

Sorry, that I don't see this earlier. Yes, cookies have integer values, so
we won't be able to set string there. May be we can have a reserved integer
cookie value for a project like all "1".

I won't support idea of modifying cleanup logic not to drop 0x0 cookies.
During implementation of graceful restart it was not dropped at first, but
I get rid of it  as having a lot of flows not related to anything was not
desirable, so we should try to avoid it here, too.

On Wed, Dec 16, 2015 at 7:46 AM, Soichi Shigeta <
shigeta.soichi at jp.fujitsu.com> wrote:

>    o) An idea to fix:
>>       1. Set "taas" stamp(*) to taas flows.
>>       2. Modify the cleanup logic in ovs-agent not to delete entries
>>          stamped as "taas".
>>       * Maybe a static string.
>>         If we need to use a string which generated dynamically
>>         (e.g. uuid), API to interact with ovs-agent is required.
>   Last week I proposed to set a static string (e.g. "taas") as cookie
>   of flows created by taas agent.
>   But I found that the value of a cookie should not be a string,
>   but an integer.
>   At line 187 in
> "neutron/neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py":
>   self.agent_uuid_stamp = uuid.uuid4().int & UINT64_BITMASK
>   In case of we set an integer value to cookie, coordination
>   (reservation of range) is required to avoid conflict of cookies with
>   other neutron sub-projects.
>   As an alternative (*** short term ***) solution, my idea is:
>   Modify the clean up logic in ovs agent not to delete flows whose
>   "cookie = 0x0".
>   Because old flows created by ovs agent have an old stamp, "cookie =
>   0x0" means it was created by other than ovs agent.
>   # But, this idea has a disadvantage:
>     If there are flows which have been created by older version of ovs
>     agent, they can not be cleaned.
> ---
>  Soichi Shigeta
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Ann Kamyshnikova
Mirantis, Inc
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