On 2023-06-27 11:18, Roberto Bartzen Acosta wrote:
Hi Gary,

Em ter., 27 de jun. de 2023 às 11:47, Yatin Karel <ykarel@redhat.com> escreveu:
Hi Gary,

On top what Rodolfo said
On Tue, Jun 27, 2023 at 5:15 PM Gary Molenkamp <molenkam@uwo.ca> wrote:
Good morning,   I'm having a problem with snat routing under OVN but I'm
not sure if something is mis-configured or just my understanding of how
OVN is architected is wrong.

I've built a Zed cloud, since upgraded to Antelope, using the Neutron
Manual install method here:
https://docs.openstack.org/neutron/latest/install/ovn/manual_install.html
I'm using a multi-tenent configuration using geneve and the flat
provider network is present on each hypervisor. Each hypervisor is
connected to the physical provider network, along with the tenent
network and is tagged as an external chassis under OVN.
         br-int exists, as does br-provider
         ovs-vsctl set open .
external-ids:ovn-cms-options=enable-chassis-as-gw

Any specific reason to enable gateway on compute nodes? Generally it's recommended to use controller/network nodes as gateway. What's your env(number of controllers, network, compute nodes)?

Wouldn't it be interesting to enable-chassis-as-gw on the compute nodes, just in case you want to use DVR: If that's the case, you need to map the external bridge (ovs-vsctl set open . external-ids:ovn-bridge-mappings=...) via ansible this is created automatically, but in the manual installation I didn't see any mention of it.

Our intention was to distribute the routing on our OVN cloud to take advantage of DVR as our provider network is just a tagged vlan in our physical infrastructure.  This avoids requiring dedicated network node(s) and fewer bottlenecks.  I had not set up any ovn-bridge-mappings as it was not mentioned in the manual install.  I will look into it.


 
The problem is basically that the port of the OVN LRP may not be in the same chassis as the VM that failed (since the CR-LRP will be where the first VM of that network will be created). The suggestion is to remove the enable-chassis-as-gw from the compute nodes to allow the VM to forward traffic via tunneling/Geneve to the chassis where the LRP resides.


I forced a similar VM onto the same chassis as the working VM, and it was able to communicate out.    If we do want to keep multiple chassis' as gateways, would that be addressed with the ovn-bridge-mappings?




ovs-vsctl remove open . external-ids ovn-cms-options="enable-chassis-as-gw" ovs-vsctl remove open . external-ids ovn-bridge-mappings ip link set br-provider-name down ovs-vsctl del-br br-provider-name systemctl restart ovn-controller systemctl restart openvswitch-switch 




-- 
Gary Molenkamp			Science Technology Services
Systems Administrator		University of Western Ontario
molenkam@uwo.ca                 http://sts.sci.uwo.ca
(519) 661-2111 x86882		(519) 661-3566