Hi, On Thu, May 29, 2025 at 4:50 PM engineer2024 via discuss < ovs-discuss@openvswitch.org> wrote:
> Hi, > > i have an openstack ovn setup. For sriov neutron ports, when the cms > option is set on the compute node hosting the sriov nic, as shown below > > "ovs-vsctl set Open_vSwitch . external-ids:ovn-cms-options=\" > enable-chassis-as-extport-host\"" > > the port is getting the dhcp ip. Now, my question is, from where is the > OVN responding to this external port's DHCP reqs ? I know for a normal > tap port , it goes through br-int and then the ovn-controller gives the > response. but the sriov port by passes the whole ovs and the host's kernel > network stack. But where does it go to after it exits the physical VF > interface, and how does OVN answer it ? How and where does OVN's inbuilt > dhcp service maintained ? > > DHCP will be answered wherever your external port is scheduled. I recommend reading this blogpost I wrote some time back: https://dani.foroselectronica.es/ovn-external-ports-604/ If you're seeing this behavior and you are 100% sure that the same compute node that has the SRIOV port is serving the DHCP requests to that instance then it means that the broadcast request is coming out from the SRIOV port and back in from the same switch presumably to the compute node through a different NIC and from there to br-ex (or similar?) -> br-int -> external-port. I'm not entirely sure about the return path though but you can possibly check with tcpdump :) > Next, for sriov ports, the nova metadata service is also unreachable, as, > it bypasses the ovn-meta namespace on the compute host connected to the > br-int via veth cables. So injecting user data like ssh keys is not > possible and failing... > Same... you should have the ovn-metadata-agent running where your external port is and this one will proxy the metadata request to nova and serve it back to your sriov instance wherever it is. > > Thanks > elinux > _______________________________________________ > discuss mailing list > disc...@openvswitch.org > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss >
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