On 25 Mar 2024, at 13:37, Ilya Maximets wrote:
> On 3/25/24 13:22, Aaron Conole wrote: >> Eelco Chaudron <echau...@redhat.com> writes: >> >>> On 22 Mar 2024, at 20:06, Aaron Conole wrote: >>> >>>> Open vSwitch is originally intended to switch at layer 2, only dealing with >>>> Ethernet frames. With the introduction of l3 tunnels support, it crossed >>>> into the realm of needing to care a bit about some routing details when >>>> making forwarding decisions. If an oversized packet would need to be >>>> fragmented during this forwarding decision, there is a chance for pmtu >>>> to get involved and generate a routing exception. This is gated by the >>>> skbuff->pkt_type field. >>>> >>>> When a flow is already loaded into the openvswitch module this field is >>>> set up and transitioned properly as a packet moves from one port to >>>> another. In the case that a packet execute is invoked after a flow is >>>> newly installed this field is not properly initialized. This causes the >>>> pmtud mechanism to omit sending the required exception messages across >>>> the tunnel boundary and a second attempt needs to be made to make sure >>>> that the routing exception is properly setup. To fix this, we set the >>>> outgoing packet's pkt_type to PACKET_OUTGOING, since it can only get >>>> to the openvswitch module via a port device or packet command. >>> >>> Is this not a problem when the packet comes from the bridge port in the >>> kernel? >> >> It very well may be an issue there as well, but the recommendation is to >> operate with the bridge port down as far as I know, so I don't know if >> this issue has been observed happening from the bridge port. > > FWIW, bridge ports are typically used as an entry point for tunneled > traffic so it can egress from a physical port attached to OVS. It means > they are pretty much always UP in most common setups like OpenStack or > ovn-kubernetes and handle a decent amount of traffic. They are also used > to direct some other types of traffic to the host kernel. +1 here, I’m talking about the same port. I think we only advise having this down for userspace bridges, but not in the case the bridge is the tunnel endpoint. > Unless I misunderstood which ports we're talking about here. > > Best regards, Ilya Maximets. _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
