Hi Hooman,

Please see inline...

On Tue, Feb 9, 2021 at 8:36 PM Bidgoli, Hooman (Nokia - CA/Ottawa)
<[email protected]> wrote:
>
> Hi Dhruv
>
> Much appreciate your reply, Inline
>
> Thanks
> Hooman
>
>
> -----Original Message-----
> From: Dhruv Dhody <[email protected]>
> Sent: Tuesday, February 9, 2021 5:28 AM
> To: Bidgoli, Hooman (Nokia - CA/Ottawa) <[email protected]>
> Cc: [email protected]; [email protected]
> Subject: Re: draft-hsd-pce-sr-p2mp-policy wiki comments and action.
>
> Hi Hooman,
>
> Apologies! Missed replying to this email...
>
> On Fri, Jan 22, 2021 at 12:27 AM Bidgoli, Hooman (Nokia - CA/Ottawa) 
> <[email protected]> wrote:
> >
> > Dear Chairs
> >
> >
> >
> > Looking at the wiki page there was a comment on the sr-p2mp-policy draft.
> >
> >
> >
> > draft-hsd-pce-sr-p2mp-policy
> >
> > 109; More work is needed - align to PCECC, text needs to aligned to
> > the PCE WG style
> >
> >
> >
> > The authors took an action to setup a meeting and discuss the alignment 
> > with PCECC farther. The final outcome of this meeting was unanimous 
> > agreement, by all the authors/vendors on the draft, to go forward with ERO 
> > object.
> >
> >
>
> As an individual I-D, it is up to the co-authors to decide the content of the 
> I-D.
>
> The comment (and earlier discussions) was to make sure we maintain 
> consistency across all our documents that we produce. RFC 8283 describes the 
> PCECC architecture, where the PCE needs to interact with not only the 
> head-end routers (the usual stateful/stateless PCE case) but also with the 
> egress and the internal P routers. The WG has just sent the first PCECC 
> extension for MPLS label allocation along the path to the IESG. For other use 
> cases such as SR/SRv6 SID allocation as well as for the branch node in the 
> P2MP LSP and Native-IP, all are under the PCECC umbrella. So far all use 
> cases where the PCE needs to interact with other nodes beyond the ingress and 
> provide instructions to them are using PCECC architecture.
>
> So when the PCE is interacting with the head end for SR P2MP Policy, it can 
> use the usual stateful PCE extensions but when the PCE is interacting with 
> the branch nodes and leaf nodes for replication segment, we strongly feel it 
> should be described under the PCECC architecture. So you could use the ERO 
> object for encoding the full P2MP path (and SR P2MP Policy) when interacting 
> with the root node.
> But when interacting with other nodes, use the PCECC technique i.e. a new CCI 
> object type (which could be used with the ERO if needed). This would help you 
> to not reinvent things as well as maintain consistency.
> To reconfirm, the PCECC comment is related to section 3.3.3 & 4.5 only and 
> not the whole document. If you still disagree please list the technical 
> reason why so that the WG can evaluate them.
>
> HB> As I am sure you do appreciate there are many ways to skin the cat. 
> TreeSID can be connected via unicast SR path and not every node needs to be 
> programmed. In addition as explained the PCECC did not provide the with 
> flexibility to configure backup/fast reroute paths and the current methods 
> does provide that capability.
> Again as mentioned we looked at PCECC very hard and tried to implement 
> treeSID via this method but there were major short comings for backup and FRR 
> paths.
> There are multiple implementation in the field that is using the ERO object 
> for treeSID with success.
> Are the chairs suggesting that the working group is only dictating PCECC and 
> is not open to any other option but PCECC for the purpose of programming the 
> PCC and multicast?
> We have been asking for adaptation since 3 IETF ago and we keep getting 
> pushback because our implementation does not follow the PCECC, why is PCECC 
> the only choice on the table? Why isn't the working group open to other 
> options to solve the multicast requirements? Given the fact that the ERO has 
> been implemented and is in the field and in multiple providers labs being 
> tested with successful outcome, I think the WG should have a open view to 
> this implantation. Especially when multiple vendors and providers (Cisco, 
> Juniper, Nokia, Ciena, Bell Canada) to name a few have agreed to this 
> implementation.
>
>

[Dhruv]: I feel there is some misunderstanding here. The PCECC
extensions defined a new object called CCI, with different
object-types to be defined for various use-cases. There is common
handling for all such instructions and it is defined once and can be
reused across multiple use cases. I understand that you want to use
the ERO object with multi-path, and that *is* fine, you could in fact
easily define the RBNF in such a way that both CCI and ERO are
included for the new CCI object type for SR-P2MP.

Thanks!
Dhruv

> >
> > The authors feel ERO object in addition to draft-koldychev-pce-multipath-04 
> > - PCEP Extensions for Signaling Multipath Information (ietf.org) for backup 
> > paths is the easiest and the most efficient way to address the programming 
> > of a replication segment on PCC from to the PCE.
> >
> >
> >
> > The authors would like to move forward with the adaptation call please. In 
> > addition the authors are open to discuss the ERO preference in an interim 
> > open session with the chairs.
> >
> >
>
> The document has not been updated after 109, last we discussed this, we found 
> that the document needed more work because it does not follow the way the 
> PCEP extensions are usually defined. It follows a very unusual format (e.g. 
> section 5) at places. It is good to provide examples but suggest it be done 
> in a way that is more readable. Please follow the RBNF notations when 
> specifying PCEP message changes (in a backward-compatible way). Some of your 
> co-authors have vast experience in writing documents in this WG, I suggest 
> taking their help. Hopefully, a more readable version will help you get more 
> reviews.
>
> HB> sure this is cosmetics and we will follow the WG suggestion, that said 
> this should not stop the adaptation call. The sooner we have adaptation call 
> the sooner we can have input.
>
> HB> to close, as you mentioned some of the co-authors have vast experience in 
> PCE WG and the same co-authors have agreed and recommended ERO 
> implementation. As such I ask the chairs for adaptation call again ASAP. We 
> will fix the cosmetics to be inline with WG recommendations asap.
>
>
>
> Hope this helps, and again accept our apologies for missing replying to this 
> email earlier.
>
> Thanks!
> Dhruv & Julien
>
> >
> > Regards
> >
> > Hooman
> >
> >
> >
> >

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