Hi Giuseppe,

Thanks for your response. Perhaps my point was not clear and so let me please 
clarify.

I am seeing the IFIT signalling related drafts for BGP and PCEP (it was also 
there in LSR?) in their individual protocol working groups. While what these 
protocols are doing is only "carrying" (in case of BGP somewhat opaquely) the 
information and conveying it to the SR Policy Module (SRPM). The following may 
clarify the picture better : 
https://tools.ietf.org/html/draft-filsfils-spring-sr-policy-considerations-06#section-2

The key part of how this is handled by the SRPM, the related procedures and 
setup in the forwarding plane along with their applicability and any other 
considerations should be (IMHO) done in a Spring document. This is my 
suggestion and request to the authors - not to add all of this into an IDR 
document since that is not where you will find the right expertise to review 
these aspects.

Without that, it might seem like an uncoordinated protocol development effort 
for those of us who are not intimately aware of all the IFIT internals/details.

Rest, I will leave it up to the chairs of the WGs involved.

Thanks,
Ketan

From: Giuseppe Fioccola <giuseppe.fiocc...@huawei.com>
Sent: 16 November 2020 12:42
To: Ketan Talaulikar (ketant) <ket...@cisco.com>; Susan Hares 
<sha...@ndzh.com>; i...@ietf.org
Cc: spring@ietf.org
Subject: RE: [Idr] IPR Call and WG Adoption for 
draft-qin-idr-sr-policy-ifit-04.txt (11/1/2020 to 11/16/2020)

Hi Ketan,
Thanks a lot for your revision.
My answers inline tagged as [GF]

Regards,

Giuseppe

From: Ketan Talaulikar (ketant) [mailto:ket...@cisco.com]
Sent: Friday, November 13, 2020 12:12 PM
To: Giuseppe Fioccola 
<giuseppe.fiocc...@huawei.com<mailto:giuseppe.fiocc...@huawei.com>>; Susan 
Hares <sha...@ndzh.com<mailto:sha...@ndzh.com>>; 
i...@ietf.org<mailto:i...@ietf.org>
Cc: spring@ietf.org<mailto:spring@ietf.org>
Subject: RE: [Idr] IPR Call and WG Adoption for 
draft-qin-idr-sr-policy-ifit-04.txt (11/1/2020 to 11/16/2020)

Hi Giuseppe,

First of all, thanks for making the updates to the document to clarify the 
objective and applicability of IFIT and this draft extensions specifically to 
the SR Policy signalled by BGP. A good part of the puzzle is at least clearer 
to me now.

Sec 3 says (and I am trying to paraphrase here - so please correct me), that 
these IFIT attributes (new TLVs) are signalled via BGP along with the SR Policy 
Candidate Path to "enable IOAM and Alternate Marking" mechanisms for that SR 
Policy. This way all traffic steered over that SR Policy with have the IOAM and 
Alt Marking headers inserted on them.

[GF]: Yes, this is correct.

Is there a Spring WG document that describes the implications of actually how 
this would get applied to the SR Policy forwarding planes (SR-MPLS and SRv6) 
and what types of Steering would be possible to be used for such SR Policies 
(ref 
https://tools.ietf.org/html/draft-ietf-spring-segment-routing-policy-09#section-8).
 ? E.g. if a packet is arriving at the headend with a stack of labels and gets 
steered via BSID into such an SR Policy where "IFIT is applied", how does that 
work?

[GF]: Good point, in the next revision we can add some considerations on the 
Steering into an SR Policy. This can be useful also for the data plane drafts. 
Regarding SRv6, the relevant documents are already adopted: 
draft-ietf-ippm-ioam-ipv6-options for IOAM and draft-ietf-6man-ipv6-alt-mark 
for AltMark. These Options are defined for IPv6 and can be used with any 
Routing Header (including SRH). For SR-MPLS the relevant documents (e.g. 
draft-gandhi-spring-ioam-sr-mpls) are still individual.


Sec 6 (SR Policy operations with IFIT Attributes) says the following:

The validation of the individual fields of the IFIT
   Attributes sub-TLVs are handled by the SRPM (SR Policy Module).

However, I am still missing a document that describes how these are actually 
"handled" by the SRPM?

[GF]: draft-ietf-idr-segment-routing-te-policy also mentions some high-level 
functionality of SRPM. I think we need to include more details in 
draft-qin-idr-sr-policy-ifit in order to describe the functionalities that are 
specific for IFIT (IOAM and AltMark).

I understand that there is a similar draft in PCE WG as well, but it is also 
missing this information.

[GF]: I can address this comment in both drafts.

My concern is that we have documents for the protocol signaling mechanisms for 
IFIT but I am not able to locate a document that describes how exactly this 
information is going to get used/applied by SRPM.

[GF]: Some details about the SRPM operation for IFIT could be added in this 
draft.

Please do point/clarify if I am missing something here.

Thanks,
Ketan

From: Idr <idr-boun...@ietf.org<mailto:idr-boun...@ietf.org>> On Behalf Of 
Giuseppe Fioccola
Sent: 02 November 2020 22:28
To: Susan Hares <sha...@ndzh.com<mailto:sha...@ndzh.com>>; 
i...@ietf.org<mailto:i...@ietf.org>
Subject: Re: [Idr] IPR Call and WG Adoption for 
draft-qin-idr-sr-policy-ifit-04.txt (11/1/2020 to 11/16/2020)

Dear Susan, All,
I'm not aware of any IPR related to this draft. I also support its adoption as 
coauthor.

Best Regards,

Giuseppe


From: Idr [mailto:idr-boun...@ietf.org] On Behalf Of Susan Hares
Sent: Monday, November 2, 2020 6:57 AM
To: i...@ietf.org<mailto:i...@ietf.org>
Subject: [Idr] IPR Call and WG Adoption for draft-qin-idr-sr-policy-ifit-04.txt 
(11/1/2020 to 11/16/2020)

This begins a 2 week WG adoption call for draft-qin-idr-sr-policy-ifit-04.txt 
(11/2/2020 to 11/16/2020).

The draft can be accessed at:
https://datatracker.ietf.org/doc/draft-zhu-idr-bgp-ls-path-mtu/

The authors should provide IPR statements by 11/5/2020 so the IDR WG can 
consider the IPR status in their
decision.

This draft adds the IFIT sub-TLV to the BGP Tunnel Encaps attribute for the SR 
policy tunnel type. This sub-TLV is only valid for SR Policy tunnel types.  
Within the IFIT  sub-TLV value field, 5 sub-TLVs may be included (4 for IOAM 
and 1 for Enhanced Alternate Marking).

The IDR co-chairs thank the authors for their patience.  The WG adoption call 
for this draft has been delayed by the process of switching shepherds for BGP 
Tunnel Encaps draft.  Many BESS and IDR drafts currently refer to the BGP 
tunnel encapsulation drafts.

In your review of this draft, please differentiate between the following:

  *   Support/rejection of In-situ Flow Telemetry (IFIT) as a IP routing 
technology,
  *   Support/rejection of alternate marking as a IP routing technology,
  *   Support/rejection of adding new sub-TLVS for SR Policy tunnel type of BGP 
Tunnel Encap Attribute, and
  *   Specific issues with the descriptions of these features in the draft.

Cheers, Susan Hares



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