Eelco Chaudron <[email protected]> writes: > On 25 Mar 2024, at 13:37, Ilya Maximets wrote: > >> On 3/25/24 13:22, Aaron Conole wrote: >>> Eelco Chaudron <[email protected]> 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.
Okay, I'll confirm about up/down, but it seems like it shouldn't matter and we should be setting the outgoing type. >> Unless I misunderstood which ports we're talking about here. >> >> Best regards, Ilya Maximets. _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
