[mpls] Re: Poll: IOAM and PSD

[Rakesh Gandhi <[e-mail]>]

Hi Greg,

Sorry for top posting, I am replying to the following comment:

Regarding:
GIM>> Could you please point me where the use of Timestamp in RFC 9326
IOAM-DEX is required or even discussed as optional?

<RG>

As IOAM DEX option-type is extensible using the Extension-Flags defined in
RFC 9326, there are new drafts proposed in the IPPM WG to take advantage of
it, i.e. to add additional metadata and telemetry information in
direct-export option.



https://datatracker.ietf.org/doc/html/rfc9326

    0                   1                   2                   3

    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |        Namespace-ID           |     Flags     |*Extension-Flags*|

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |               IOAM-Trace-Type                 |   Reserved    |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                         Flow ID (Optional)                    |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   |                     Sequence Number  (Optional)               |

   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



   1. *Adding Measurement period number information for alternate marking:*


   -
   https://datatracker.ietf.org/doc/draft-he-ippm-integrating-am-into-ioam/



        0                   1                   2                   3

        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       |        Namespace-ID           |     Flags     |*Extension-Flags*|

       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       |               IOAM-Trace-Type                 |D|L| Reserved  |

       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       |                         Flow ID (Optional)                    |

       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

       |                     Sequence Number  (Optional)               |

       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

*       |             Measurement Period Number  (Optional)             |*

       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



               Figure 1: The Extended DEX Option-Type Format



   - IANA has created the "IOAM DEX Extension-Flags" registry. This
   registry includes 8 flag bits. Bit 0 (the most significant bit) and bit 1
   in the registry are allocated by [RFC9326]. IANA is requested to allocate
   bit 2 as Measurement Period Number in the registry and described in Section
   5.



*(2): Adding timestamp information:*

   -
   https://www.ietf.org/archive/id/draft-ahuang-ippm-dex-timestamp-ext-00.txt



     0                   1                   2                   3

     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |        Namespace-ID           |     Flags     |*Extension-Flags*|

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |               IOAM-Trace-Type                 |   Reserved    |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                         Flow ID (Optional)                    |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

     |                     Sequence Number  (Optional)               |

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

*     |                   Timestamp Seconds  (Optional)               |*

*     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+*

*     |                  Timestamp Fraction  (Optional)               |*

     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+



       Figure 1: IOAM DEX Option-Type Format including the timestamps





Thanks,

Rakesh




On Mon, Aug 5, 2024 at 6:43 PM Greg Mirsky <[e-mail]> wrote:

> Hi Rakesh,
> I have a number of questions based on you responses and would greatly
> appreciate your helping me to better understand. I'll top-post below and
> tag my questions with GIM>>:
>
>    - Based on my understanding, two IOAM option-types, namely,
>    Pre-allocated Trace (value 0) and Direct-Export (value 4) are popular.
>
> GIM>> What is the measure of "popular"? HW implementations?
>
>    - Data fields such as 32-bit Sequence Number or 32-bit Timestamp in
>    In-Stack LSE can lead to undesired ECMP behavior on nodes that use labels
>    for ECMP hashing
>
> *GIM>> Could you please point me where the use of Timestamp in RFC 9326
> IOAM-DEX is required or even discussed as optional?*
>
> Regards,
> Greg
>
> On Mon, Aug 5, 2024 at 3:32 PM Rakesh Gandhi <[e-mail]>
> wrote:
>
>> Hi Tony,
>>
>>
>>
>> Although not directly related to the question in the poll but since PSD
>> is mentioned in the title of this email for poll, like to highlight the
>> certain advantages of adding IOAM data fields in Post-Stack Network Action
>> for both post-card based and passport-based methods.
>>
>>
>>
>>    1. IOAM E2E/POT/TRACE/DEX option-types contain various data fields as
>>    defined in RFC 9197 and RFC 9326
>>    <https://datatracker.ietf.org/doc/html/rfc9326>.
>>    2. Data fields such as 32-bit Sequence Number or 32-bit Timestamp in
>>    In-Stack LSE can lead to undesired ECMP behavior on nodes that use labels
>>    for ECMP hashing
>>       - Data fields in Post-Stack are not included in ECMP hashing
>>    3. 32-bit data fields do not fit into 30-bit data in In-Stack LSE,
>>    limited to 11-bit as variable or mutable data
>>    - RFC standard IOAM format data fields fit well into 32-bit
>>       Post-Stack Network Action Data
>>       4. IOAM option types support extensibility to optionally add many
>>    data fields
>>       - Node can easily skip In-Stack network action and process the
>>       next one even when Data in Post-Stack is outside RLD
>>    5. IOAM-DEX data fields can be seen as metadata in the received
>>    packets that data plane exports
>>       - Metadata could easily be in Post-Stack
>>
>>
>> P.S. The IOAM network action and offset for the data fields for both IOAM
>> methods would be in-stack. The above points are for the data fields.
>>
>>
>> Thanks,
>>
>> Rakesh
>>
>>
>>
>> On Tue, Jul 30, 2024 at 11:27 AM Tony Li <[e-mail]> wrote:
>>
>>> [WG chair hat: on]
>>>
>>>
>>>
>>> Hi all,
>>>
>>>
>>>
>>> We’ve had many discussions about IOAM and PSD over the last few years.
>>> We need to reach consensus on the problems that need to be addressed in
>>> these areas. Therefore, we would like to hear from everyone, especially
>>> independent operators:
>>>
>>>
>>>
>>>    1.
>>>
>>>    There are many flavors of IOAM.  Which ones would you like to
>>>    deploy/implement with MNA?
>>>    2.
>>>
>>>    Do you have other applications of MNA that have not been proposed
>>>    yet?
>>>
>>>
>>>
>>>  This poll will close in two weeks, at 9am PDT, Aug 13.
>>>
>>>
>>>
>>> Regards,
>>>
>>> MPLS chairs
>>>
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>