Re: Opinion on WG drafts for Multi-region/layer networks

[Kohei Shiomoto <shiomoto.kohei@lab.ntt.co.jp>]

Hi Huub

Thank you for your support and comments.
Please see in line.

Huub van Helvoort wrote:

> Hello JL,
> 
> You explained:
> 
>>> two questions: 1. since MLN is a special case of MRN, can we
>>> collapse this whole topic to MRN? is there a compelling reason for
>>> keeping these 2 notation?
>>
>>
>> Actually a MLN is not a special case of MRN. Rather a MRN is a
>> special case of MLN. A network comprised of VC4 and VC4-64c capable
>> node is a MLN but not a MRN. "Layer" refers to a data plane switching
>> layer (e.g. VC4, VC4-64c...). While "region" refers to a switching
>> capablity (PSC, TDM...). The term MLN is used to discuss mechanisms
>> that apply equally to layers and regions (VNT...) while the term MRN
>> is used to discuss multi-regions specific mechanisms (e.g. Adaptation
>> capability).
> 
> 
> I am still confused by the definition of MRN.
> Suppose I have a TDM MRN, I can distinguish in this TDM MRN e.g.
> VC-12 layer switching, VC-4 layer switching, MS-n layer switching,
> so according to the above all MLN.
> Why is an MRN then a special case of MLN.

As JL explained, a MRN is a special case of MLN.  As far as the same
interface switching capability is used, the MLN is not called the MRN
[RFC4206]. The same switching type is used in control plane as long as
it is in the same region. The switching type TDM is used in control
plane of the TDM multi-layer network consisting of VC-12 and VC-4 for
instance.

A region uniquely identifies a particular data plane technology (PSC,
L2SC, TDM, LSC, and FSC) while a layer describes a data plane switching
granularity level. A region (e.g. TDM) can be sub-divided into smaller
granularity based on the bandwidth that defines the "data plane
switching layers" (e.g. from VC-11 to VC4-256c in TDM). In other words,
more than one data plane layer can be associated to the same region
(e.g. both VC4 and VC12 are associated to TDM).

> 
> With the next generation nodes: Multi Service Platforms within
> the same node there can also be ethernet switching on top of
> the above mentioned TDM MRN and optical switching (DWDM) below
> this TDM MRN....
> 
> IMO the definition of MRN will be very difficult (impossible).
> 
> I would propose to use only the MLN definition, with this layering
> and partitioning a network can be described completely.

Thank you for your comments. Again a MRN is a special case of MLN. The
term MLN could replace the term MRN in our documents where appropriate.
We should see whether appropriate wording is used in the next revision
to resolve confusion.

> 
> Cheers, Huub.
> 

Thanks,
Kohei