[ovs-discuss] Router not allowing traffic in reverse

John Carew johnwcarew at gmail.com
Fri Mar 1 00:34:17 UTC 2019

I think there is some misunderstanding, I don't think OVS is working incorrectly or has a problem. I believe it is working exactly how it is configured. I believe OpenStack is just configuring OVS, and it has put in a flow rule or something that is allowing outbound for a network/subnet but not inbound. I'm asking how to figure out where in OVS it is stopping at.

> On Feb 28, 2019, at 5:51 PM, Ben Pfaff <blp at ovn.org> wrote:
> Do you have a reason to believe that it's a problem in OVS, rather than
> a problem in what OpenStack is telling OVS to do?
> On Thu, Feb 28, 2019 at 04:48:44PM -0600, John Carew wrote:
>> I agree, but I want to diagnose what is causing it in ovs first before I go to them.
>> John
>>>> On Feb 28, 2019, at 4:33 PM, Ben Pfaff <blp at ovn.org> wrote:
>>>> On Wed, Feb 27, 2019 at 09:26:16PM -0600, John Carew wrote:
>>>> I have setup OpenStack with OVS. I have a single Hyper-V server running the
>>>> controller and three CentOS instances(10.0.0.x) on a private subnet. I
>>>> created a router in OpenStack with SNAT disabled, as I only want it to route
>>>> traffic between the private subnet(10.0.0.x) and the external
>>>> subnet(172.16.1.x)/internet. All of the instances can ping each other along
>>>> with the external network(172.16.1.x). From the external network, I can ping
>>>> the interface of the ovs router on the external network. I can not though
>>>> ping inside the private network. A trace route stops at the IP of the OVS
>>>> router. With wireshark, I do not see anything coming from the external pc’s
>>>> IP. If I trace route it, I see packets making all the way to the OVS router
>>>> and then stop. Since I can ping one way, and not the other; I believe there
>>>> is something in the router/OVS that is stopping the packets to route into
>>>> the private subnet. What do I need to look at? (I have disabled all
>>>> firewalls on all OSes involved.)
>>> An OpenStack mailing list might be a better place to track this down.
>>> OpenStack programs and configures OVS; OVS by itself doesn't have much
>>> to do with what's going on.

More information about the discuss mailing list