Hi Jesse, On Wed, Jul 13, 2016 at 07:35:59AM -0700, Jesse Gross wrote: > On Wed, Jul 13, 2016 at 4:04 AM, Brady Allen Johnson > <brady.allen.john...@ericsson.com> wrote: > > I wanted to mention though, currently the type 2 metadata (MD2) isnt a top > > priority for us. It looks like its already been investigated how to use some > > existing OVS TLV code to implement this, so it should be easy to add MD2 in > > the future. Can we consider first merging the core NSH functionality without > > MD2, and then submit MD2 in a subsequent patch? > > I think history tells us how this will end - similar to IPv4 options, > implementations that don't implement TLVs will become deployed and > then when there is a use for them it's no longer possible. Since I > don't want OVS to have a half implementation or contribute to this > issue, I'd like to see the whole protocol implemented before I apply > anything.
I see your point but I also see value in incrementally implementing a full solution. If anything I feel that the current patch-set is already on the large side though of course the design could be fleshed out to some extent independently of the implementation and submitted patches. With regards to TLVs my understanding is that NSH specifies that they be used to encode metadata for MD type 2. That is a bridge we will need to cross at some point and I think any insight you have would be very valuable given your experience with Geneve and encapsulation in general. However, with MD type 1, the only other MD type defined in draft-ietf-sfc-nsh-01, there are simply four mandatory 32-bit wide context headers. If my reading of Johnson's patchset is correct then these are implemented as 4 fields in the flow key which are exposed to Open Flow. This seems like a reasonable approach to me which does seem to preclude supporting MD type 2 as well. But I suppose it would also be possible to encode then by a different means that also covers type 2 metadata. _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
