[snip] >>> Picking up the topic of trunc on patch port. >>> >>> Instead of banning trunc output to a patch port, any down side of >>> translating that >>> to trunc, clone(<patch port translation>)? After all, native tunneling >>> looks a lot like patch port conceptually. >> >> How does clone() interact with trunc() in the datapath? >> >> As I understand, before clone() existed in datapath (at least linux >> side), the trunc() would only apply to the next output(). >> Conceptually, if trunc(),clone(...) applies the truncation for the >> duration of the clone() then that sounds fine. > > That's the proposal on the table. Conceptually, we just treat clone > as another output. > > I'm a little concerned >> that a really small truncate value should actually affect parsing of >> packet headers for subsequent tables/lookups though. > > Isn't this the inherent problem with trunc? trunc causes a packet > to become a partial packet, that may cause subsequent actions > to fail. > > All of this is a >> lot simpler if it's tied directly to the output, but now that we're >> looking at handling the translation over another bridge without >> re-extracting the packet it gets more complex. > > What is the additional complexity over handling patch ports > over that of native tunneling?
Before the tunneling: Avoid recirculation on datapath (commit f1dac51), handling truncate and native tunneling is simple. The native tunneling applies the tunnel metadata and output to the tunnel port, and truncation applies at before the outputting tunnel port. And because we will recirculate and re-parse, the flow key and stats are also correct after re-parsing and matching on the truncated packet. IMO, handling truncate and patch port is way more complex. It means translation over another bridge without re-parsing, and the packet could match to do anything including native tunneling. If the only use case of truncate is to sample/mirror, then what if we allow trunc and patch port, and applies actual packet truncation before sending to the patch port? Like Joe mentioned, another bridge might match fields truncated, or actions might fail, but its inherent issue of truncate and users should know about it. Regards, William _______________________________________________ dev mailing list d...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-dev
