Re: [nvo3] Working Group Last Call and IPR Poll for draft-ietf-nvo3-geneve-08.txt

Greg,

The 'O' bit does not override or interact with the Protocol Type
field, so there is no issue with precedence. It is possible to
implement OAM on Geneve using options, in which case the payload could
be a stub of a packet to ensure consistent behavior between OAM and
data packets as has been done with other protocols. In this situation,
the Protocol Type would still indicate the type of the stub packet as
usual. It is also possible to implement OAM using the payload of the
packet as you describe and the Protocol Type would indicate that using
an EtherType assigned for this purpose.

In either case, the meaning of the 'O' bit is the same and it only
affects the behavior of endpoint devices processing OAM. Most devices
are oblivious to this and will simply use the Protocol Type field to
process the payload as usual. The appropriate behavior for 'O' bit
flagged packets is described in the draft:

      Endpoints MUST NOT forward the payload and
      transit devices MUST NOT attempt to interpret or process it.
      Since these are infrequent control messages, it is RECOMMENDED
      that endpoints direct these packets to a high priority control
      queue (for example, to direct the packet to a general purpose CPU
      from a forwarding ASIC or to separate out control traffic on a
      NIC).  Transit devices MUST NOT alter forwarding behavior on the
      basis of this bit, such as ECMP link selection.

The 'O' bit does not otherwise change the interpretation of the packet.

Jesse

On Mon, Oct 15, 2018 at 6:01 PM Greg Mirsky <gregimirsky@gmail.com> wrote:
>
> Dear All,
> I am concerned that the current definition of O-bit contradicts the definition of the Protocol Type field. Consider that O-bit defined as:
>    O (1 bit):  OAM packet.  This packet contains a control message
>       instead of a data payload.
> My interpretation, please correct me if it is wrong, is that the O-bit indicates that a message that immediately follows the Geneve header is
> OAM command or data. But that is what the Protocol Type field is for:
>    Protocol Type (16 bits):  The type of the protocol data unit
>       appearing after the Geneve header.
> What is the precedence processing O-bit and the Protocol Type values? Should the specification explain how to interpret the value of the Protocol type field when O-bit is set? If the value of the Protocol Type field is equivalent to None, i.e., no message following the Geneve header, can O-bit be set to indicate that one of TLVs includes OAM? If that is the valid case, then the current definition of O-bit is not complete as it does not mention OAM in TLV case.
>
> And I have to point to an overall lack of discussion of OAM in the specification.
>
> Regards,
> Greg
>
> On Tue, Oct 9, 2018 at 2:08 AM Bocci, Matthew (Nokia - GB) <matthew.bocci@nokia.com> wrote:
>>
>> This email begins a two-week working group last call for draft-ietf-nvo3-geneve-08.txt.
>>
>> Please review the draft and post any comments to the NVO3 working group list. If you have read the latest version of the draft but have no comments and believe it is ready for publication as a standards track RFC, please also indicate so to the WG email list.
>>
>>
>>
>> We are also polling for knowledge of any undisclosed IPR that applies to this document, to ensure that IPR has been disclosed in compliance with IETF IPR rules (see RFCs 3979, 4879, 3669 and 5378 for more details).
>>
>> If you are listed as an Author or a Contributor of this document, please respond to this email and indicate whether or not you are aware of any relevant undisclosed IPR. The Document won't progress without answers from all the Authors and Contributors.
>>
>> Currently there are two IPR disclosures against this document.
>>
>> If you are not listed as an Author or a Contributor, then please explicitly respond only if you are aware of any IPR that has not yet been disclosed in conformance with IETF rules.
>>
>>
>>
>> This poll will run until Friday 26th October.
>>
>>
>>
>> Regards
>>
>>
>>
>> Matthew and Sam
>>
>> _______________________________________________
>> nvo3 mailing list
>> nvo3@ietf.org
>> https://www.ietf.org/mailman/listinfo/nvo3