Re: [Bier] Comments on draft-ietf-bier-pmmm-oam-04

[Greg Mirsky <[e-mail]>]

Hi Saneesh,
thank you for your feedback. Please kindly consider the update to the draft
reflected in the attached diff. Please let us know if the changes address
your comments.

Regards,
Greg

On Mon, Nov 26, 2018 at 4:31 PM Suneesh <[e-mail]> wrote:

> Thanks Greg for the update, please find my comments inline below.
>
> Regards,
> Suneesh
>
> On Thu, Nov 22, 2018 at 12:09 AM Greg Mirsky <[e-mail]>
> wrote:
>
>> Now with the updated address to reach Giuseppe.
>>
>> On Wed, Nov 21, 2018 at 10:37 AM Greg Mirsky <[e-mail]>
>> wrote:
>>
>>> Hi Suneesh,
>>> thank you for the feedback and the detailed questions. Please find my
>>> responses and notes in-line below tagged GIM>>.
>>>
>>> Regards,
>>> Greg
>>>
>>> On Mon, Nov 19, 2018 at 9:24 AM Suneesh <[e-mail]> wrote:
>>>
>>>> Hi Greg,
>>>>
>>>> I have following comments on PMMM draft, please share your thoughts.
>>>>
>>>> Q1. Can you please share how the draft is viewed as a hybrid model?
>>>>
>>> GIM>> RFC 7799 provided the definition of active and passive measurement
>>> methods. Hybrid methods are "in between" these two groups. Even though the
>>> Alternate marking in BIER domain may use already preallocated field, it
>>> does change the content of the header by applying the marking values in the
>>> OAM field. Thus it is neither passive, nor active method but "in between",
>>> i.e., hybrid. Would you agree?
>>>
>> Suneesh>>> Agreed
>
>>
>>>> Ref: Section-3:
>>>>
>>>> <snip>
>>>>    the marking method in BIER layer can be viewed as the example of the
>>>>    hybrid performance measurement method
>>>> </snip>
>>>>
>>>>
>>>> Q2. Can you please define what is meant by sub-flows
>>>>    a). Is the sub-flow set of flows on which marking method is applied
>>>> OR
>>>>    b). sub-flow-1 with say marking 0 and sub flow-2 with say marking 1
>>>> OR
>>>>    c). Being a hybrid model, draft proposes to duplicate the multicast
>>>> stream which is having marking and treated those as sub-flows?
>>>>
>>> GIM>> We use the term "sub-flow" as you've described in b).
>>>
>> Suneesh>>> Would be great if we can capture in the draft for more
> clarity
>
>> Ref: Section-4: Theory of Operation
>>>> <snip>
>>>>    Using the marking method a BFR creates distinct sub-flows in the
>>>>    particular multicast traffic over BIER layer
>>>> </snip>
>>>>
>>>>
>>>> Q3. Is there any recommended values for 'number of packets' or/and
>>>> 'time duration' for alternate marking method
>>>>     a). Just to know what is recommended to avoid say number of
>>>> packets/time duration = 1
>>>>
>>> GIM>> You're right, 1 or even 2 would not be useful. 3 packets? May be.
>>>
>>>>
>>>> Q4. Lets say that the nodes is like A->B->C->D->F->G->H->I, the segment
>>>> of interest is B->C->D for performance measurement
>>>>   a). Does the alternate marking values will clear from node D onwards?
>>>>   b). If not, what is recommended if we wish to measure between G->H->I
>>>>
>>> GIM>> Very good question. It is expected that the marking values be
>>> cleared at the edge of BIER domain and thus an operator may enable
>>> measurements on segment G-H-I at any time.
>>>
>> Suneesh>> Please consider adding it to the draft
>
>>
>>>> Ref: Section-4: Theory of Operation
>>>>
>>>> <snip>
>>>>   Any combination of markings, Loss and/or Delay, can be applied to a
>>>> multicast flow by
>>>>   any Bit Forwarding Router (BFR) at either ingress or egress point to
>>>>    perform node, link, segment or end-to-end measurement to detect
>>>>    performance degradation defect and localize it efficiently.
>>>> </snip>
>>>>
>>>> Q5. Can we somewhere capture that 'proto' field of BIER header should
>>>> not be "OAM request/reply", though we are using OAM bits in header.
>>>>
>>>> <snip>
>>>>    The OAM field MUST be used only
>>>>    for the performance measurement of data traffic in BIER layer.
>>>> </snip>
>>>>
>>>>
>>> GIM>> I think it would be too restrictive. One may want to measure
>>> performance of BIER OAM.
>>>
>> Suneesh >>> I understood your point. Thanks.
>
>
>> Regards,
>>>> Suneesh
>>>>
>>>