Subject: [Detnet-dp-dt] an attempt on math for global pools of labels

From: Loa Andersson <[email-masked]>
Date: Wed, 22 Feb 2017 18:59:33 +0800

Folks,

Figures are not scientific, just off the top of my head.

Assume that we have 400 edge nodes and the receiving and sending
capability of each node is 2400 G and the average DetNet flow is 1G,
and the traffic matrix is close to even.

This means that each node will need 2400 Labels to manage as a pool for
the d-pw labels if we go with the idea to make them unique for the
entire domain. 400 * 2400 = 960 000 which brings us close to exhausting 
the label space.

I real life I don't think that the average speed is as high as 1G, if it
were "only" 500 M, the label space would be exhausted.

/Loa
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Loa Andersson                        email: [email-masked]
Senior MPLS Expert                          [email-masked]
Huawei Technologies (consultant)     phone: +46 739 81 21 64

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From: Carlos Jesús Bernardos Cano <[email-masked]>
Date: Wed, 22 Feb 2017 12:41:36 +0100

Hi Loa,

I agree it is worth doing this kind of rough estimate. I guess we need
also some insights from use cases to do a better estimate. 

> entire domain. 400 * 2400 = 960 000 which brings us close to

So you assume that all edge nodes are saturated, right? Is this a
reasonable assumption? I have some doubts, but this is just a personal
feeling.

And, what do we assume of the inner topology/nodes capacities? because
unless the topology is really meshed, that number of flows would
generate an aggregated throughput (especially considering that some
nodes will be doing replication of packets) in some nodes that is
probably higher than what the links can support, no?

Thanks,

Carlos

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From: Loa Andersson <[email-masked]>
Date: Wed, 22 Feb 2017 19:46:35 +0800

Yes,  it is true that it is rough, but normally I want a scaling factor
of at least 10 (or more).

/Loa

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From: Carlos Jesús Bernardos Cano <[email-masked]>
Date: Wed, 22 Feb 2017 12:54:28 +0100

Hi Loa,

> of at least 10 (or more).

Sure, fully agree. But you can also assume that all edge network nodes
will not be operating in saturation mode all the time, no?

Carlos
 
> > > This means that each node will need 2400 Labels to manage as a
> > > pool
> > > for
> > > I real life I don't think that the average speed is as high as
> > > 1G, if
> > > it

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From: Loa Andersson <[email-masked]>
Date: Wed, 22 Feb 2017 20:00:28 +0800

Carlos,

The distribution of the poll will be relatively static, even if one node
is operating in saturation, the limited availability of labels will
cause problem for that node.

/Loa

On 2017-02-22 19:54, Carlos Jesús Bernardos Cano wrote:
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