Re: [mpls] draft-iwijnand-mpls-mldp-multi-topology - review

Gyan Mishra <hayabusagsm@gmail.com> Tue, 17 May 2022 17:09 UTC

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From: Gyan Mishra <hayabusagsm@gmail.com>
Date: Tue, 17 May 2022 13:09:24 -0400
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To: "Mankamana Mishra (mankamis)" <mankamis@cisco.com>
Cc: "draft-iwijnand-mpls-mldp-multi-topology@ietf.org" <draft-iwijnand-mpls-mldp-multi-topology@ietf.org>, mpls <mpls@ietf.org>
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Subject: Re: [mpls] draft-iwijnand-mpls-mldp-multi-topology - review
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Welcome!

Thanks you Mankamana.

Gyan
On Tue, May 17, 2022 at 11:51 AM Mankamana Mishra (mankamis) <
mankamis@cisco.com> wrote:

> Thanks Gyan for input. I would wait for WG comment and chairs input about
> keeping it single document or make it two. May we that can be discussed
> even after adoption.
>
>
>
> Mankamana
>
>
>
> *From: *mpls <mpls-bounces@ietf.org> on behalf of Gyan Mishra <
> hayabusagsm@gmail.com>
> *Date: *Sunday, May 8, 2022 at 10:52 PM
> *To: *draft-iwijnand-mpls-mldp-multi-topology@ietf.org <
> draft-iwijnand-mpls-mldp-multi-topology@ietf.org>, mpls <mpls@ietf.org>
> *Subject: *Re: [mpls] draft-iwijnand-mpls-mldp-multi-topology - review
>
>
>
> Dear authors
>
>
>
> I see the draft is in queue for WG adoption so I have provided a quick
> review prior to the adoption call.
>
>
>
> The original draft published in 2011 and the goal was to extend mLDP  P2MP
> and MP2MP FEC RFC 6388  to be IGP MTID aware OSPF MT RFC 4915 and ISIS RFC
> 5130.
>
>
>
> The replacement draft with same name posted in 2018 added support for IGP
> Flex Algo and so now the latest draft revision 4  extends mLDP RFC 6388 to
> support both IGP MTID which was the basis of the original draft as well as
> now Flex Algo added to the draft.
>
>
>
> MT IGP concept provides a common data plane with separation of control
> plane functionality, thereby giving the ability for operators to create sub
> topologies “network slices” of the topology as an  IGP abstraction layering
> at the control plane level.
>
>
>
> Flex Algo  draft was originally published in 2017 and now been submitted
> for publication.
>
>
>
> The goal of  Flex Algo was to also provide a simpler control plane based
> “network slicing” capabilities but with simplification as well as current
> applicability to only SR forwarding plane association of Algo with SR-MPLS
> prefix SIDs or SRv6 locators.
>
>
>
> One of the goals of SR-MPLS is the elimination of network state by moving
>  the LDP control plane state to an SR IGP extension.
>
>
>
> As multicast has been challenging for operators migrating to SR,
> flexibility to keep LDP around for multicast only -  mLDP had been common
> place and gives operators some time  to migrate to some of the up and
> coming SR based multicast technologies.
>
>
>
> This draft provides an extends mLDP FEC to be FAD aware as well as the
> original goal of making MTR aware.
>
>
>
> Throughout the document Flex Algo and MTR are mentioned and as the
> extension that was originally for IGP MT, is now being extended to support
> as well Flex Algo using the basis of RFC 7307 making LDP MTID aware.
>
>
>
> My thoughts are it would be easier to keep the existing document
> development in 2011 which goal was to extend mLDP to support MT and
> creating a separate draft for extending mLDP to support Flex Algo.
>
>
>
> Bundling both solutions together seems overly complicated as MT is very
> different from FAD.  Also bundling together confuses the overall solution.
>
>
>
> If you extend Flex Algo separately you don’t require any dependencies  on
> RFC 7307 as now it would be a completely new solution and can focus on FAD
> 3 tuple and getting that encoded into a new FEC P2MP and MP2MP FEC.  I
> think this drastically simplifies the solution.
>
>
>
> IGP Flex Algo only supports SR Algo today and is being extended to support
> other data planes such as now IP Flex Algo.
>
>
>
> As IGP flex Algo draft today only supports SR data plane association with
> prefix sid for SR-MPLS and SRv6 locator for SRv6, I think Flex Algo would
> first require an extension to support MPLS LDP which does not exist today.
> So that’s a major problem.
>
>
>
> So if Flex Algo today does not support MPLS LDP data plane, how can you
> extend mLDP (multipoint extension of LDP)  to support Flex Algo?
>
>
>
> I think this is an important solution and would be happy to collaborate on
> the draft to help progress.
>
>
>
> Kind Regards
>
>
>
> Gyan
>
>
>
>
>
> --
>
> <http://www.verizon.com/>
>
> *Gyan Mishra*
>
> *Network Solutions Architect *
>
> *Email gyan.s.mishra@verizon.com <gyan.s.mishra@verizon.com>*
>
> *M 301 502-1347*
>
>
>
-- 

<http://www.verizon.com/>

*Gyan Mishra*

*Network Solutions A**rchitect *

*Email gyan.s.mishra@verizon.com <gyan.s.mishra@verizon.com>*



*M 301 502-1347*