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

[Gyan Mishra <[e-mail]>]

Hi Acee

Do you know if the dynamic flooding algorithm discussed during interim ietf
by Sarah and Toni is the same as the one implemented by Cisco on Nexus
platform or is Cisco’s Dynamic flooding a proprietary implementation?

Cisco’s flooding algorithm does seem almost identical to dynamic flooding.

Cisco Dynamic flooding - Nexus 9k

https://www.cisco.com/c/en/us/products/collateral/switches/nexus-9000-series-switches/white-paper-c11-743015.html


Dynamic Flooding - Arista - Sarah & Toni

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

Flood reduction- H Chen - WG adoption pending

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


I know we are trying to adopt an flooding algorithm
and from my reading up on all proposed algorithms, the dynamic flooding
seems to be geared towards Data Center  partial mesh high x ECMP leaf spine
architecture, where redundant flooding is problematic using either
centralized area leader or distributed flooding using same dynamic
algorithm,  versus the call for adoption flood reduction algorithm seems to
geared towards full mesh but from what I can tell would not be the
preferred for clos multi tier DC leaf spine topology with high x ECMP paths.

Why would we not want to adopt the best algorithm that is best for both
full mesh and non full mesh leaf spine topology algorithm that works for
all physical topologies and adopt that draft.

Unless a one size fits all won’t work I would like to understand why one
best solution draft we come up with for an FT algorithm for all possible
physical topologies cannot be picked for WG adoption.

Why would we want to adopt multiple flooding algorithms?

Gyan

On Sat, May 23, 2020 at 4:43 PM Gyan Mishra <[e-mail]> wrote:

>
>
> On Fri, May 22, 2020 at 9:02 PM <[e-mail]> wrote:
>
>>
>> Hi Gyan,
>>
>> I think with clos spine leaf the mesh is much more intensive and
>> problematic with ECMP then a circular topology nodal mesh that results in
>> duplicate redundant flooding that slows down convergence.  With spine leaf
>> it’s like an X horizontal width axis and then depth is spine to leaf
>> links.  With spine leaf as you grow sideways and the spine expand the
>> redundant ECMP grows and redundant flooding grows exponentially and is much
>> worse then circular nodal mesh.
>>
>>
>> One very nice thing about dynamic flooding is that it computes a flooding
>> topology at the node level.  If the adjacency between A and B is on the
>> flooding topology, then any single link between them may be used for
>> flooding.  If you have 128 way parallel links, this is an immediate 128x
>> improvement in flooding overhead.  What’s more, A and B do not need to
>> agree on which link they are using and can use different links, resulting
>> in an asymmetric situation, without any loss of correctness or performance.
>>
>
>    Gyan>. Agreed.  The dynamic flooding really helps with X way ECMP
> prevalent in high density data center clos multi tier leaf spine parial
> mesh topologies that scale massive bandwidth breadth wise horizontally for
> E-W flows.
>
>>
>> Regards,
>> Tony
>>
>> --
>
> <http://www.verizon.com/>
>
> *Gyan Mishra*
>
> *Network Solutions A**rchitect *
>
>
>
> *M 301 502-134713101 Columbia Pike *Silver Spring, MD
>
> --

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

*Gyan Mishra*

*Network Solutions A**rchitect *



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