On 27/08/14 15:43, Tom Herbert wrote: > On Tue, Aug 26, 2014 at 11:13 PM, Anton Ivanov > <[email protected]> wrote: >> On 26/08/14 22:42, Tom Herbert wrote: >>> On Tue, Aug 26, 2014 at 2:09 PM, Anton Ivanov >>> <[email protected]> wrote: >>>> On 26/08/14 21:47, Tom Herbert wrote: >>>>> Remote checksum offload is intended to be used to get checksum offload >>>>> of encapsulated packets to work with legacy NICs (those that don't >>>>> understand encapsulation protocols). I will be posting an >>>>> implementation to Linux shortly for GUE and/or Geneve. >>>> This one was floated on the mailing list during the IETF-89 (and >>>> immediately thereabouts) discussions around geneve, fixed/floating >>>> headers, etc a while back. >>>> >>>> We have had a working implementation for the GRE case for a while now >>>> (we have it in a limited release product based around UML in customer >>>> labs). I need to get around to contribute it upstream (in fact, I was >>>> going to work on the patchsets this week). >>>> >>> You extended GRE with fields for checksum offload? >> GRE has an optional checksum already as per RFC 2784 - nothing to extend. >> >> If it is computed at source and checked by hardware or hypervisor at >> destination you can compute the payload checksum from the GRE checksum >> and pass it to the guest. It is an excellent reference example for your >> idea because it can be implemented today using IP_HDRINCL which is not >> yet possible for the UDP encaps as there is no sane way to get to the >> header and get the csum from it for those without changing the kernel. >> If nvGRE had the checksum specified (which it presently does not) it >> could have been subjected to the same technique. >> > I don't think we're talking about same thing. I think you're referring > to an offloading technique for receive side, which yes, can be done > without protocol change pretty easily. Remote checksum offload is > meant to offload the transmit checksum computation for encapsulation, > which I believe does need some protocol assistance.
Either that or OOB control plane configuration which says for this Virtual Network Identifier and/or source compute all checksums, the frames are coming without ones. F.E. for gre key 0x012345678 compute the checksums before re-xmitting. IMHO it is not strictly necessary to stick this into the protocol. A. > > _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
