What metadata is propagating?
On Thu, Apr 05, 2018 at 08:14:51PM +0200, Alan Kayahan wrote: > I introduced a new 32bit field in flow.h to match on. A push_header action > appends a header, which contains TLVs, to the packet and sets this field > for the first time. An increment action sets this field to a value that > resides in the first TLV, if increment action is called again, the field is > set to the value in the second TLV and so on. > > I have a chain of br0-br1-br2 connected via patch ports. In br0 flow rule > calls push_header and out to br1. In br1, the flow rule matches on the port > connected to br0, plus match on the 32bit field.The action for this rule is > increment, then out to br2. Just like br1, br2 matches on the port from br1 > plus the match on the 32bit field for the value in the TLV. > > Everything works well until br2. But the match on the field for the value > in the TLV doesn't work. If I remove the match on the field at br2 and just > use in_port and redirect the traffic to packet hex printer, I do see that > the value in the TLV has been set correctly at the offset of this 32bit > field. > > The increment action depends on the iteration of TLVs in the header at each > packet, therefore is at datapath and can not update the flow context. So if > the flow metadata is propagating (which seems to be the only explanation), > the new field is set to the old value, which is the culprit. Perhaps a > better approach is to create an own context just like nat, iterate the TLVs > and populate the context with all available values when push_header is > first called, then redesign the increment action so that it just pops the > next value from the context and emits the data-plane action. Eliminates > TLVs iteration per packet at the dataplane. > > But just to save the day, do you have a trick to stop this propagation? Or > do you think the problem might be something else? > > Thanks! > > 2018-04-05 19:41 GMT+02:00 Ben Pfaff <b...@ovn.org>: > > > On Thu, Apr 05, 2018 at 07:31:35PM +0200, Alan Kayahan wrote: > > > OVS patch ports allow the propagation of the metadata (e.g. flow context) > > > across the connected switches. > > > > > > Is there an option to disable the metadata propagation feature? I need > > this > > > for my research to benchmark certain behavior. Or patch ports become > > > nothing but veth pairs when this feature is disabled? > > > > Patch ports zero out most metadata. What additional metadata do you > > want them to clear? > > _______________________________________________ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss