Re: [Lsr] Flooding Topology Computation Algorithm - draft-cc-lsr-flooding-reduction-08 Working Group Adoption Call

[Gyan Mishra <[e-mail]>]

I think for both drafts it would be good to have a stick diagram at a
minimum.

I majored in EE with math  minor and both drafts are hard to follow without
a diagram with labels showing the exact topology examples.

Four main topologies - full mesh, partial mesh and leaf spine ( 2 tier) and
CLOS ( 3 tier) - real world scenario’s.

>From the interim meeting was their a slide deck visual topology shared?

That would help.

https://datatracker.ietf.org/doc/html/draft-cc-lsr-flooding-reduction-08

4.1

Step 1 - Build Cq candidate queue

For each node B on FT whose D is one (from minimum to maximum
       node ID), find a link L attached to B such that L's remote node R
       has minimum D and ID, add link L between B and R into FT and
       increase B's D and R's D by one.  Return FT.

My interpretation is the algorithm an iterative loop and starts with any
node in the candidate list so could start from edge and work left to right
or vice versa.  For loop to build FT from Cq = with each node B with
directly attached node R via link L.  Increment node B from Cq until the FT
is build for all nodes.  Instead of starting with a wide diameter FT
matching physical topology we start micro topology with D=1 and go node by
node.

4.2

1.  Finding and removing the first element with node A in Cq that is
       not on FT and one PH's D in PHs < MaxD and PH's D < PH's ConMaxD.

       If A is root R0, then add the element into FT

       otherwise  (i.e., A != R0 with one PH's D in PHs < MaxD and PH's
          D < PH's ConMaxD.  Assume that PH is the first one in PHs
          whose D < MaxD and PH's D < PH's ConMaxD), PH's D++, and add A
          with D = 1 and PHs = {PH} into FT.

       Note:  if there is no element with a node in Cq satisfying the
          conditions, then algorithm may be restarted from R0, ++MaxD,
          Cq = {(R0,D=0,PHs = { })}, FT = { };

This is similar to 4.1 with micro topology with 2 directly connected nodes

https://www.ietf.org/id/draft-chen-lsr-dynamic-flooding-algorithm-00.html

My interpretation of the algorithm from the verbiage.

So this draft starts in the middle of the topology and is geared towards
leaf spine 2 or 3 tier clos topology.

For this one we build the bi graph so that could be leaf connected to two
spines or spine connected to two leafs and iteratively build out the FT
topology 3 node arch  spine leaf spine or leaf spine leaf.

Kind regards

Gyan

On Thu, May 21, 2020 at 7:01 PM Acee Lindem (acee) <[e-mail]> wrote:

> Hi Gyan,
>
>
>
> *From: *Gyan Mishra <[e-mail]>
> *Date: *Thursday, May 21, 2020 at 4:20 PM
> *To: *Acee Lindem <[e-mail]>
> *Cc: *Huaimo Chen <[e-mail]>, "[e-mail]" <
> [e-mail]>
> *Subject: *Re: [Lsr] Flooding Topology Computation Algorithm -
> draft-cc-lsr-flooding-reduction-08 Working Group Adoption Call
>
>
>
>
>
> Yes and I have started reviewing the LSR mail archives as I am late in the
> discussion for this.
>
>
>
> If you have link to any particular dates in the archives would be helpful.
>
>
>
> No – it was more an “evolution” than an “epiphany”.
>
>
>
> That sums up all the questions I have so if all answered in the archives
> then I am all set.
>
>
>
> I support the draft moving forward as flood reduction is a much needed
> feature.
>
>
>
> I think overall both drafts will really help large data centers with any
> overlay underlay vxlan spine leaf meshed CLOS highly meshed topology that
> scales out horizontally with a large spine footprint - this is a much much
> needed feature.  This also helps eliminate complexity of the workaround of
> using BGP in the underlay which to me adds tremendous complexity.
>
>
>
> Here is the other recently presented dynamic flooding draft.
>
>
>
> https://datatracker.ietf.org/doc/draft-chen-lsr-dynamic-flooding-algorithm/
>
>
>
> You can see they both make use of the dynamic flooding infra in
> https://datatracker.ietf.org/doc/draft-ietf-lsr-dynamic-flooding/
>
>
>
> Thanks,
>
> Acee
>
>
>
>
>
>
>
>
>
> Kind regards
>
>
>
> Gyan
>
>
>
> On Thu, May 21, 2020 at 4:07 PM Acee Lindem (acee) <[e-mail]> wrote:
>
> Speaking as WG Co-chair:
>
>
>
> Hi Gyan,
>
>
>
> I guess you’ve joined this discussion late. It might be a good idea to
> review the LSR mailing list archives.
>
>
>
> *From: *Gyan Mishra <[e-mail]>
> *Date: *Thursday, May 21, 2020 at 1:51 PM
> *To: *Huaimo Chen <[e-mail]>
> *Cc: *Acee Lindem <[e-mail]>, "[e-mail]" <[e-mail]>
> *Subject: *Re: [Lsr] Flooding Topology Computation Algorithm -
> draft-cc-lsr-flooding-reduction-08 Working Group Adoption Call
>
>
>
>
>
>
>
> On Thu, May 21, 2020 at 11:01 AM Huaimo Chen <[e-mail]>
> wrote:
>
> Hi Gyan,
>
>
>
>     Thanks much for your questions.
>
>
>
>  Gyan> How does this draft compare to the WG LC draft for flood
> reduction.  Would they be two eventual standard options in the operators
> toolbox  or competing features for optimized flood reduction. Would having
> two flood reduction features standardized versus one default IGP flood
> reduction feature be confusing for operators.  Just as it was confusing to
> me.
>
> https://datatracker.ietf.org/doc/draft-ietf-lsr-dynamic-flooding/
> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-ietf-lsr-dynamic-flooding%2F&data=02%7C01%7Chuaimo.chen%40futurewei.com%7C60df274544ba4b75447f08d7fd947201%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637256686327604003&sdata=TGrkecn6m9liviazX7qqPglGqYEWu5Ekg2FRIaDpBZ8%3D&reserved=0>
>
>
>
>     [HC]: This draft plus the draft for flooding reduction can provide two
> modes of flooding reductions (i.e., centralized mode and distributed mode).
> The latter describes the two modes, but does not include any flooding
> topology computation algorithm for the distributed mode. The former
> proposes a flooding topology computation algorithm to be used in the
> distributed mode.
>
>
>
>    Gyan> It maybe a good idea for both documents to reference each other
> as to how they play together or  in some respects if any provide a
> homogeneous complete holistic solution for flooding problem being solved.
>
>
>
> It is a good idea to have this new draft reference the dynamic-flooding
> but not vice-versa. The existing dynamic flooding draft provides a
> framework for any dynamic flooding algorithm that provides a separate
> flooding topology. This algorithm is just the first to be formally proposed
> in a draft. Note that another algorithm was presented during the LSR
> virtual interim which replaced IETF 107.
>
>
>
> In my opinion it may not be a bad idea even to combine both drafts so the
> solution is complete and holistic.  This will also make the overall
> specification flow nicely.
>
>
>
> No – we’re not going to do this.
>
>
>
> Thanks,
>
> Acee
>
>
>
> I know that efforts were made by LSR to have a common IGP solution,
> however there are many inherent differences between ISIS and OSPF that from
> IGP Link state protocol perspective you can treat like apples to apples but
> really it’s apples and oranges.  Maybe it might we wise to have separate
> draft for both and have references linking together as the same algorithm
> concept and mathematically however the actual code implementation would
> vary as the LSDB link state data structures are completely different.
>
>
>
> Later = Dynamic flooding = 2 modes Centralized leader based and
> distributed
>
>
>
> https://datatracker.ietf.org/doc/draft-ietf-lsr-dynamic-flooding/
>
>
>
> This later draft per section excerpt provides both centralized and
> distributed algorithm see below
>
>
>
> *6.4 <https://datatracker.ietf.org/doc/html/draft-ietf-lsr-dynamic-flooding-05#section-6.4>.  Area Leader Responsibilities*
>
>
>
>    If the Area Leader operates in centralized mode, it MUST advertise
>
>    algorithm 0 in its Area Leader Sub-TLV.  In order for Dynamic
>
>    Flooding to be enabled it also MUST compute and advertise a flooding
>
>    topology for the area.  The Area Leader may update the flooding
>
>    topology at any time, however, it should not destabilize the network
>
>    with undue or overly frequent topology changes.  If the Area Leader
>
>    operates in centralized mode and needs to advertise a new flooding
>
>    topology, it floods the new flooding topology on both the new and old
>
>    flooding topologies.
>
>
>
>    If the Area Leader operates in distributed mode, it MUST advertise a
>
>    non-zero algorithm in its Area Leader Sub-TLV.
>
>
>
>    When the Area Leader advertises algorithm 0 in its Area Leader Sub-
>
>    TLV and does not advertise a flooding topology, Dynamic Flooding is
>
>    disabled for the area.  Note this applies whether the Area Leader
>
>    intends to operate in centralized mode or in distributed mode.
>
>
>
>    Note that once Dynamic Flooding is enabled, disabling it risks
>
>    destabilizing the network.
>
>
>
> *6.5 <https://datatracker.ietf.org/doc/html/draft-ietf-lsr-dynamic-flooding-05#section-6.5>.  Distributed Flooding Topology Calculation*
>
>
>
>    If the Area Leader advertises a non-zero algorithm in its Area Leader
>
>    Sub-TLV, all nodes in the area that support Dynamic Flooding and the
>
>    value of algorithm advertised by the Area Leader MUST compute the
>
>    flooding topology based on the Area Leader's advertised algorithm.
>
>
>
>    Nodes that do not support the value of algorithm advertised by the
>
>    Area Leader MUST continue to use standard flooding mechanism as
>
>    defined by the protocol.
>
>
>
>    Nodes that do not support the value of algorithm advertised by the
>
>    Area Leader MUST be considered as Dynamic Flooding incapable nodes by
>
>    the Area Leader.
>
>
>
>    If the value of the algorithm advertised by the Area Leader is from
>
>    the range 128-254 (private distributed algorithms), it is the responsibility of the
>
> network operator to guarantee that all nodes in the area have a common understanding of what the given algorithm value represents.
>
>
>
> Former = WG LC
>
> https://datatracker.ietf.org/doc/html/draft-cc-lsr-flooding-reduction-08
>
>
>
> Provides algorithm for distributed mode for this draft as well as the
> algorithm to be used for distributed mode later dynamic flooding draft
>
>
>
> Separate question-
>
>
>
> In light of the flooding algorithm and seeing that at the bottom of
> section 6.5 mentions flooding algorithm are the IANA codepoints reserved
> for flooding unique and non overlapping with the flex algo codepoints I
> believe 0-127.  I would think the flooding algorithm range of values is
> completely separate since a different function then flex algo values.
>
>
>
> https://datatracker.ietf.org/doc/html/draft-ietf-lsr-flex-algo-07
>
>
>
>
>
> Best Regards,
>
> Huaimo
> ------------------------------
>
> *From:* Gyan Mishra <[e-mail]>
> *Sent:* Thursday, May 21, 2020 10:36 AM
>
>
> *To:* Huaimo Chen <[e-mail]>
> *Cc:* Acee Lindem (acee) <acee=[e-mail]>; [e-mail] <
> [e-mail]>
> *Subject:* Re: [Lsr] Flooding Topology Computation Algorithm -
> draft-cc-lsr-flooding-reduction-08 Working Group Adoption Call
>
>
>
>
>
>
>
> On Wed, May 20, 2020 at 11:59 PM Huaimo Chen <[e-mail]>
> wrote:
>
> Hi Gyan,
>
>
>
>     Thanks much for your questions. My answers are inline below with [HC].
>
>
>
> Best Regards,
>
> Huaimo
> ------------------------------
>
> *From:* Gyan Mishra <[e-mail]>
> *Sent:* Wednesday, May 20, 2020 11:14 AM
> *To:* Huaimo Chen <[e-mail]>
> *Cc:* Acee Lindem (acee) <acee=[e-mail]>; [e-mail] <
> [e-mail]>
> *Subject:* Re: [Lsr] Flooding Topology Computation Algorithm -
> draft-cc-lsr-flooding-reduction-08 Working Group Adoption Call
>
>
>
> Huaimo
>
>
>
> This is a much needed feature that operators have been needing for densely
> meshed topologies that commonly exist in data centers to accommodate very
> high bandwidth E-W traffic.
>
> [HC]: Thank you very much.
>
>
>
> Below is link from Cisco which has introduced feature for dynamic flooding
> in clos high density ECMP data center topologies.
>
>
>
> Please look at the feature description and it does seem to be exactly the
> same as this draft.  Please confirm.
>
> [HC]: It seems different.
>
>
>
> There maybe other vendors due to industry demand have to get the feature
> deployed before it reaches standards vendor consensus with the IETF.
>
>
>
>
> https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/white-paper-c11-743015.html
> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.cisco.com%2Fc%2Fen%2Fus%2Fproducts%2Fcollateral%2Fswitches%2Fnexus-9000-series-switches%2Fwhite-paper-c11-743015.html&data=02%7C01%7Chuaimo.chen%40futurewei.com%7C60df274544ba4b75447f08d7fd947201%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637256686327604003&sdata=CPEu2451qkfD9440Ihj1bKPWl%2BzH%2BiuYUwuWpfzR%2B0Q%3D&reserved=0>
>
>
>
> We are testing this feature and planning to deploy but wanted to ensure
> that this is the same as the draft on the standards track.
>
> [HC]: The feature appears implemented draft "Dynamic Flooding on Dense
> Graphs", which does not include any flooding topology computation
> algorithm..
>
>
>
>     Gyan> How does this draft compare to the WG LC draft for flood
> reduction.  Would they be two eventual standard options in the operators
> toolbox  or competing features for optimized flood reduction. Would having
> two flood reduction features standardized versus one default IGP flood
> reduction feature be confusing for operators.  Just as it was confusing to
> me.
>
>
>
>
>
> https://datatracker.ietf.org/doc/draft-ietf-lsr-dynamic-flooding/
> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-ietf-lsr-dynamic-flooding%2F&data=02%7C01%7Chuaimo.chen%40futurewei.com%7C60df274544ba4b75447f08d7fd947201%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637256686327604003&sdata=TGrkecn6m9liviazX7qqPglGqYEWu5Ekg2FRIaDpBZ8%3D&reserved=0>
>
>
>
> Kind regards
>
>
>
> Gyan
>
>
>
>
>
> On Tue, May 19, 2020 at 11:52 PM Huaimo Chen <[e-mail]>
> wrote:
>
> Hi Gyan,
>
>
>
>     Thank you very much for your questions and support.
>
>
>
>     This Flooding Topology Computation algorithm can be used in the
> Dynamic Flooding on Dense Graphs to compute the flooding topologies for
> the data center clos dense meshed topologies with many ECMP paths. It can
> be used by the area leader in the centralized mode to compute the flooding
> topology.
>
>
>
> Best Regards,
>
> Huaimo
> ------------------------------
>
> *From:* Lsr <[e-mail]> on behalf of Gyan Mishra <
> [e-mail]>
> *Sent:* Tuesday, May 19, 2020 2:39 AM
> *To:* Yanhe Fan <[e-mail]>
> *Cc:* [e-mail] <[e-mail]>; Acee Lindem (acee) <acee=
> [e-mail]>
> *Subject:* Re: [Lsr] Flooding Topology Computation Algorithm -
> draft-cc-lsr-flooding-reduction-08 Working Group Adoption Call
>
>
>
>
>
> I support WG adoption and have a few questions related to the draft.
>
>
>
> Does this flooding algorithm use the dynamic flooding algorithm used in
> data center clos dense meshed topologies with many ECMP paths where the
> flood is decoupled from the physical topology.  In the dynamic flooding
> algorithm mentioned in centralized mode the flooding is computed by the
> area leader and distributed to all nodes.  In distributed mode each mode
> the area leader determines the algorithm and then each node computes the
> flooding topology based on the algorithm.
>
>
>
> This dynamic algorithm for optimized flood reduction would reduce the
> amount of redundant flooding in highly densely meshed ospf or Isis
> topologies.  So this optimization of flooding would improving overall link
> state routing protocol convergence.
>
>
>
> Gyan
>
>
>
> On Mon, May 18, 2020 at 3:37 PM Yanhe Fan <[e-mail]> wrote:
>
> Support it as a co-author.
>
>
>
> Thanks,
>
> Yanhe
>
>
>
> *From:* Lsr <[e-mail]> *On Behalf Of *Acee Lindem (acee)
> *Sent:* Friday, May 15, 2020 3:40 PM
> *To:* [e-mail]
> *Subject:* [Lsr] Flooding Topology Computation Algorithm -
> draft-cc-lsr-flooding-reduction-08 Working Group Adoption Call
>
>
>
> This begins a 3 week (due to holidays) WG adoption call for the “Flooding
> Topology Computation Algorithm” draft. Please issue your support or
> objection to this list by 11:59 PM, UTC on June 5th, 2020. Here is a URL
> for your convenience.
>
>
>
> https://datatracker.ietf.org/doc/draft-cc-lsr-flooding-reduction/
> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-cc-lsr-flooding-reduction%2F&data=02%7C01%7Chuaimo.chen%40futurewei.com%7C60df274544ba4b75447f08d7fd947201%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637256686327614000&sdata=FkKUWXneiQIUtjkGB6RITfo0vAt2qhkwDWB%2BghP7%2FLg%3D&reserved=0>
>
>
>
> Thanks,
> Acee
>
> _______________________________________________
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> *Gyan
> <https://www.google.com/maps/search/13101%0D%0A+Columbia+Pike+%0D%0A+Silver%0D%0A+Spring,+MD?entry=gmail&source=g>Mishra*
>
>
> <https://www.google.com/maps/search/13101%0D%0A+Columbia+Pike+%0D%0A+Silver%0D%0A+Spring,+MD?entry=gmail&source=g>*Network
> Solutions Architect *
>
>
>
> *M 301 502-1347 13101 Columbia Pike
> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.google.com%2Fmaps%2Fsearch%2F13101%2BColumbia%2BPike%2B%250D%250A%2BSilver%2BSpring%2C%2BMD%3Fentry%3Dgmail%26source%3Dg&data=02%7C01%7Chuaimo.chen%40futurewei.com%7C60df274544ba4b75447f08d7fd947201%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637256686327653980&sdata=TYHrbd1wDXt4p2yDXi%2Fqm3XEmjK4V7zu3caXeNJFthU%3D&reserved=0>
> *Silver Spring, MD
> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.google.com%2Fmaps%2Fsearch%2F13101%2BColumbia%2BPike%2B%250D%250A%2BSilver%2BSpring%2C%2BMD%3Fentry%3Dgmail%26source%3Dg&data=02%7C01%7Chuaimo.chen%40futurewei.com%7C60df274544ba4b75447f08d7fd947201%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637256686327663981&sdata=5b0tVVJLdEO9%2FuAksAsc0BAqy%2F%2F%2BE7EBPjRlkKvvOH4%3D&reserved=0>
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>
>
> --
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>
> *Gyan Mishra*
>
> *Network Solutions Architect *
>
>
>
> *M 301 502-1347
> <https://www.google.com/maps/search/13101%0D%0A+Columbia+Pike+%0D%0A+Silver%0D%0A+Spring,+MD?entry=gmail&source=g>13101
> Columbia Pike
> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.google.com%2Fmaps%2Fsearch%2F13101%2BColumbia%2BPike%2B%250D%250A%2BSilver%2BSpring%2C%2BMD%3Fentry%3Dgmail%26source%3Dg&data=02%7C01%7Chuaimo.chen%40futurewei.com%7C60df274544ba4b75447f08d7fd947201%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637256686327683966&sdata=2sVGWVhM3Sbk84D2ZyaCYUGfp5wDLt8U8uLpgMJuwSU%3D&reserved=0>
> *Silver Spring, MD
> <https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.google.com%2Fmaps%2Fsearch%2F13101%2BColumbia%2BPike%2B%250D%250A%2BSilver%2BSpring%2C%2BMD%3Fentry%3Dgmail%26source%3Dg&data=02%7C01%7Chuaimo.chen%40futurewei.com%7C60df274544ba4b75447f08d7fd947201%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C637256686327693961&sdata=OQccpoFntfT0LMaEVNaWmGhkqFbTKJLWu4PIlTuKFoA%3D&reserved=0>
>
>
>
> --
>
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>
> *Gyan Mishra*
>
> *Network Solutions Architect *
>
>
>
> *M 301 502-1347 13101 Columbia Pike
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
> *Silver Spring, MD
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>
>
>
> --
>
> *Error! Filename not specified.* <http://www.verizon.com/>
>
> *Gyan Mishra*
>
> *Network Solutions Architect *
>
>
>
> *M 301 502-1347 13101 Columbia Pike
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
> *Silver Spring, MD
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>
>
>
> --
>
> [image: Image removed by sender.] <http://www.verizon.com/>
>
> *Gyan Mishra*
>
> *Network Solutions Architect *
>
>
>
> *M 301 502-1347 13101 Columbia Pike
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
> *Silver Spring, MD
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>
> <https://www.google.com/maps/search/13101+Columbia+Pike+%0D%0A+Silver+Spring,+MD?entry=gmail&source=g>
>
>
>
-- 

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

*Gyan Mishra*

*Network Solutions A**rchitect *



*M 301 502-134713101 Columbia Pike *Silver Spring, MD