Hi Alexey, On Wed, Jan 18, 2017 at 2:14 PM, Alexey Melnikov <[email protected]> wrote: > Alexey Melnikov has entered the following ballot position for > draft-ietf-trill-directory-assist-mechanisms-11: Discuss > > When responding, please keep the subject line intact and reply to all > email addresses included in the To and CC lines. (Feel free to cut this > introductory paragraph, however.) > > ---------------------------------------------------------------------- > DISCUSS: > ---------------------------------------------------------------------- > > In Section 3.1 there is a Version field. What are the condition(s) for > bumping this version number? What backward compatibility guaranties are > expected (if any)? How would version negotiation be done?
Well, I could say that the answers to all of your questions are about the same for this Version field as they are for the RBridge Channel Header version field [RFC7178], the TRILL Header version field [RFC6325], and many other version fields in IETF protocols but you probably wouldn't consider that a very good answer. I suppose if text was being added along this lines, it should say that the version number must be incremented for a specification that does not just specify new field values where that is allowed in version zero but cannot be correctly parsed beyond the version nibble. Since the protocol is a request/response protocol, the responder should indicate the highest version number they understand but the response must be valid in the version number specified in the request including the possibility of indicating a valid error saying that the version is not implemented. Thus all implementations of version X would need to be able to at least send such an error for all versions from 0 through X-1. Then you would add an explicit suberror code in Section 3.6.3 for unimplemented version. For a version zero implementation, that would be returned for any higher version. However, I don't expect an incremented version number to be needed anytime soon. Was it your intent with this DISCUSS to get something like the above added to the draft? Thanks, Donald =============================== Donald E. Eastlake 3rd +1-508-333-2270 (cell) 155 Beaver Street, Milford, MA 01757 USA [email protected] _______________________________________________ trill mailing list [email protected] https://www.ietf.org/mailman/listinfo/trill
