[ovs-discuss] OVS-bridges Troubleshooting

aeris aeris at ytechteam.com
Thu Nov 14 09:58:13 UTC 2019

We aren't using DPDK now, ports seems to be patch ports as of some 
output of ovs-*ctl commands

About flow table what I can show ? To be more exact - which out of 300 
flows you're interested in (as output of ovs-vsctl dump-flows)?

If it is about something about "problematic" VM then -
packets:46, bytes:3404, used:0.573s, flags:PR., 

packets:46, bytes:3404, used:0.570s, flags:PR., 

Also I've tried to use "ovs-appctl ofproto/trace <bridge-name>" and none 
of my bridges accepted as an argument(Previously listed them via 
"ovs-appctl ofproto/list")

stderr told me : "ovs-appctl: ovs-vswitchd: server returned an error"

On 11/13/2019 3:29 PM, Flavio Leitner wrote:
> On Wed, 13 Nov 2019 14:02:33 +0200
> aeris <aeris at ytechteam.com> wrote:
>> Hello,
>> I'm new here, so sorry if i missed something or writing to wrong
>> maillist
>> A bit of foreword -
>> We had an installation of ovs in our cloud environment and faced
>> networking issue with vms at random time, but mostly 3-7 minutes
>> after reboot(it just stops answering on every request(typical ICMP)
>> during time from a few seconds to a few minutes)
>> Our internal network for such kind of requests looks like this -
>> Physical-switch-->linux
>> bond-->ovs-bridge1-->ovs-bridge2-->ovs-bridge3-->VM
>> With ovs-tcpdump i found that there is two-sided communication on
>> link to VM and between ovs-bridge1 and linux-bond, but only one-sided
>> communication(only icmp-replies/requests depending on from which side
>> ping was issued) on link between ovs-bridge2 and ovs-bridge3 and no
>> packet on any other interface.
>> So, actually, my main question is - what instruments do u use when
>> troubleshooting such issues, which I in turn can use in my
>> implementation. And did you faced similar problems in your
>> environments?
> I see you're using ovs-tcpdump, but you haven't told us if you're using
> DPDK or not. Also, how are the bridges connected to each other? veth?
> patch ports? and last, what do you have in the flow table?
> One thing that you might find useful is ofproto/trace:
> https://developers.redhat.com/blog/2016/10/12/tracing-packets-inside-open-vswitch/
> fbl

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