hi, On Tue, Dec 8, 2015 at 6:52 PM, Soichi Shigeta <shigeta.soi...@jp.fujitsu.com> wrote: > > Hi, > > We find a problem that neutron ovs-agent deletes taas flows. > > o) Problem description: > > Background: > At Liberty, a bug fix to drop only old flows was merged > to Neutron. > When ovs-agent is restarted, the cleanup logic drops flow > entries unless they are stamped by agent_uuid (recorded as > a cookie). > > bug: #1383674 > "Restarting neutron openvswitch agent causes network > hiccup by throwing away all flows" > https://bugs.launchpad.net/neutron/+bug/1383674 > > commit: 73673beacd75a2d9f51f15b284f1b458d32e992e (patch) > > https://git.openstack.org/cgit/openstack/neutron/commit/?id=73673beacd75a2d9f51f15b284f1b458d32e992e > > > Problem: > Cleanup will be done only once, but it seems not to work > until port configuration is changed. > > Therefore, taas flows will be deleted as follows: > 1. Start a new compute node or restart an existing compute node. > 2. Start taas agent on the compute node. > --> taas agent creates flows > (these flows are not stamped by using ovs-agent's uuid) > 3. Deploy a vm on the compute node. > --> 1. neutron changes port configuration > 2. subsequently, the cleanup logic is invoked > 3. ovs-agent drops taas flows > > Specifically, following taas flows in br_tun are dropped: > ----- > table=35, priority=2,reg0=0x0 actions=resubmit(,36) > table=35, priority=1,reg0=0x1 actions=resubmit(,36) > table=35, priority=1,reg0=0x2 actions=resubmit(,37) > ----- > > log in q-agt.log > ----- > > neutron.plugins.ml2.drivers.openvswitch.agent.openflow.ovs_ofctl.ofswitch > req-e5739280-7116-4802-b5ba-d6964b4c5557 Deleting flow > cookie=0x0, duration=434.59s, table=35, n_packets=0, n_bytes=0, > idle_age=434, priority=2,reg0=0x0 actions=resubmit(,36) > > neutron.plugins.ml2.drivers.openvswitch.agent.openflow.ovs_ofctl.ofswitch > req-e5739280-7116-4802-b5ba-d6964b4c5557 Deleting flow > cookie=0x0, duration=434.587s, table=35, n_packets=0, n_bytes=0, > idle_age=434, priority=1,reg0=0x1 actions=resubmit(,36) > > neutron.plugins.ml2.drivers.openvswitch.agent.openflow.ovs_ofctl.ofswitch > req-e5739280-7116-4802-b5ba-d6964b4c5557 Deleting flow > cookie=0x0, duration=434.583s, table=35, n_packets=0, n_bytes=0, > idle_age=434, priority=1,reg0=0x2 actions=resubmit(,37) > ----- > > > o) Impact for TaaS: > > Because flows in br_tun are dropped by the cleanup logic, mirrored > packets will not send to a monitoring vm running on another host. > > Note: Mirrored packets are sent in case of both source vm and > monitoring vm are running on the same host. (not affected by > flows in br_tun) > > > o) How to reproduce: > > 1. Start a new compute node or restart an existing compute node. > (Actually, restarting ovs-agent is enough.) > 2. Start (or restart) taas agent on the compute node. > 3. Deploy a vm on the compute node. > --> The cleanup logic drops taas flows.
i've heard qos folks had to deal with the same issues. > > > o) Workaround: > > After a vm is deployed on a (re)started compute node, restart taas > agent before creating a tap-service or tap-flow. > That is, create taas flows after cleanup has been done. > > Note that cleanup will be done only once during an ovs-agent is > running. > > > 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. > > > --- > Soichi Shigeta > > > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: openstack-dev-requ...@lists.openstack.org?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
