Re: [Rtg-ooam-dt] [nvo3] O-bit vs. OAM as Next Protocol (Re: Consensus call on encap proposals)

[Tom Herbert <[e-mail]>]

On Sun, Aug 7, 2016 at 7:02 PM, Greg Mirsky <[e-mail]> wrote:
> Dear Authors of the VxLAN-GPE, GUE, and GENEVE,
> all protocols under consideration use a bit flag rather than explicit
> protocol type to indicate that payload is a test packet, i.e. active OAM.
> I'm trying to understand the rationale of such decision. Does use of the bit
> flag rather than protocol type produce more efficient implementation, is
> more HW friendly? In GUE, the the field to indicate type of the payload even
> tagged Proto/ctype as its interpretation depends upon value of the C bit.

The C-bit in GUE distinguishes data messages from control
messages.Data messages are considered to be the payload of
encapsulation, whereas control messages are about the encapsulation
itself. OAM might be one type of control message in GUE, however there
could be others. For instance if we wanted some sort of negotiation
between two endpoints to exchange capabilities or supported features
this would fit well into a control message.

> But wouldn't it be simpler if all proposals used protocol type to identify
> OAM payload? And if the protocol type is OAM, then after the protocol header
> have OOAM Header, e.g. as proposed in . Then

Each of the three protocols has a protocol next header field, however
the field is defined differently among them. The next header in GUE is
an IP protocol number, in Geneve it is an Ethertype, and VXLAN-GPE
uses a new number space. In GUE we could probably use ICMP protocol
for OAM by defining the appropriate types (that might have the
advantage of allow OAM to be generic instead of restricted to only
encapsulation). Presumably, VXLAN-GPE could define some value in the
number space for for OAM. For Geneve maybe there is an appropriate
Ethertype?

> NVO3 protocols would be able to have common Active OAM (Fault Management and
> Performance Measurement) that can be used in BIER and SFC. And the bit, the
> bit I'd propose to redefine to be used for passive performance measurement
> as described in draft-ietf-bier-pmmm-oam. (Allocating two bits-long field
> would enable more accurate measurements using the Alternate Marking method).
> And these steps will enable us to develop common Active OAM and use passive
> performance measurement regardless, almost, of the data plane protocol used
> in NVO layer.

The problem I see with trying to constrain the solution to only one or
two bits of information is that this substantially limits the
functionality. With an extensible protocol we should be able more
information to get more accurate measurement. For instance, I might
want to measure the latency of individual packets to get feedback on
path selection, correlate performance to packet loss, etc. Has the OAM
DT considered the requirements and solutions for passive performance
measurement?

Thanks,
Tom

>
> Regards, Greg
>
> On Fri, Jul 29, 2016 at 8:13 AM, Alia Atlas <[e-mail]> wrote:
>>
>> I'd like to have people focus on the key point of this thread.
>>
>> Are there serious technical objections (and specifically what are they) to
>> moving forward with VXLAN-GPE as the standards-track protocol?
>>
>> Are there serious technical objections (and specifically what are they) to
>> moving forward with GENEVE as the standards-track protocol?
>>
>> Are there serious technical objections (and specifically what are they) to
>> moving forward with GUE as the standards-track protocol?
>>
>> We need to capture any relevant objections.  So far, there's been some
>> discussion on extensibility - with Tom Herbert providing concrete concerns.
>>
>> I have concluded that almost all the authors would prefer to have no
>> standards track solution if they can't guarantee that theirs is that
>> standard.
>>
>> I do hear concerns about whether a decision will be too late.   I think
>> that a decision can only be helpful.   It goes back to when is the best time
>> to plant a tree - with the answer of 20 years ago or now.
>>
>> Regards,
>> Alia
>>
>>
>> On Fri, Jul 29, 2016 at 4:34 AM, Naoki Matsuhira
>> <[e-mail]> wrote:
>>>
>>>
>>>
>>> On 2016/07/21 23:56, Bocci, Matthew (Nokia - GB) wrote:
>>>>
>>>> WG
>>>>
>>>> There was a discussion in the NVO3 WG meeting in Berlin following strong
>>>> advice from our Area Director that we need to come to a consensus on
>>>> converging on a common encapsulation. Two sets of questions were asked:
>>>> (1) Should the WG move forward with one standards track encap?
>>>> (2) For a given encap, do you have significant technical objections?
>>>
>>>
>>> I want to inform to this mailing list that I proposed ME6E-FP and ME6E-PR
>>> at the yokohama meeting. I also have proposal M46E-FP and M46E-PR (past
>>> called SA46T).
>>>
>>> These encapsulation technologies are based on address mapping. ME6E use
>>> IPv6 address which mapping MAC address, and M46E use IPv6 address which
>>> mapping IPv4 address.
>>>
>>> I understand too many encapsulation technologies, however these my
>>> proposal are simple, and may contribute to the Internet.
>>>
>>> I believe address mapping approach is unique, so I want to propose again.
>>>
>>> sorry not the answer to the question.
>>>
>>> Naoki Matsuhira
>>>
>>>
>>> _______________________________________________
>>> nvo3 mailing list
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>>> https://www.ietf.org/mailman/listinfo/nvo3
>>
>>
>>
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