[Nsi-wg] [Nml-wg] Conversation about ITU concepts with Ciena folks

[Victor Reijs]

Hello Jeroen,

It is important to mention that the SF does NOT determine the path to be 
tested by the Stitching Framework. It assumes a pathfinder process to 
finds a set of paths at layer 0; the SF will determine for each 
individual path if it can be supported by the specific range of 
interface settings of each peering domain.

Freek's work is at multiple levels/processes and covers more than the SF 
(it includes the path finding process as defined in AutoBAHN: at layer 0 
being connectivity at the lowest (physical) layer. So this '0' is not a 
misspelling; aka it is not layer 1.

Have next week a demo of the SF with Freek, so we can also cover this issue.

All the best,


Victor

Jeroen van der Ham wrote:
> Hello,
> 
> I agree that George's multi-layer pathfinding seems very similar to the
>  AutoBAHN approach.
> 
> Freek in his thesis argues that this approach can work, but does not
> have a way to handle incompatibilities. Freek uses an example where
> there are two ways to map Ethernet onto SONET, and the source and
> destination use different mappings.
> A path through the network will have to do a remapping along the way,
> otherwise it can't work.
> 
> I do not see how a collapsed topology can ever solve such a problem.
> Perhaps it can, but it will have to specifically supported by the
> stitching framework.
> 
> Jeroen.
> 
> Guy Roberts wrote:
>> Hi John,
>>
>> I note a couple of interesting (and to me) new points from the
>> documents provided by George Newsome.  As I see it, there are broadly
>> two ways of approaching pathfinding in multi-domain, multi-layer
>> networks:
>>
>> Approach 1:  AutoBAHN like - the layers are collapsed into a single
>> abstracted layer and pathfinding is done on this layer.  We then
>> perform stitching on a set of possible paths.
>>
>> Approach 2:  path finding is done on a complete multi-layer graph
>> with full knowledge of layer adaptations.  A much more limited (if
>> any) stitching function is then required.  I think this is more like
>> the method proposed by Freek in his thesis.
>>
>> The multi-layer pathfinding proposal included in the documents from
>> George Newsome is interesting, and in my view is close to the method
>> used by AutoBAHN, namely the topology is fattened into a single layer
>> which assumes the presence of adaptation in each node.  Pathfinding
>> is the done on this flattened topology.  The problem not addressed by
>> George Newsome is the issues covered in Victor Reijs's stitching
>> work.
>>
>> The other document of note is the transitional link document.  I
>> think we need to be careful about adopting this concept since as far
>> as I can see it has been created by ITU-T for a very specific
>> purpose.  They use it for transit between sub-layers as opposed to
>> adaptation between layers.  In their example a transitional link is
>> used for all-optical conversion of wavelengths, where wavelengths are
>> not real layers as there is no termination and adaptation function 
>> when converting between wavelengths.
>>
>> Guy
>>
>>
>> -----Original Message----- From: John Vollbrecht
>> [mailto:jrv at internet2.edu] Sent: 02 September 2009 21:53 To: NSI WG 
>> Cc: Network Markup Language Working Group; Rajender Razdan; Lyndon
>> Ong; George Newsome; Jeff Verrant; Daniel Getachew Subject: [Nsi-wg]
>> Conversation about ITU concepts with Ciena folks
>>
>>
>> Jeroen van der Ham, Guy Roberts and myself had a conversation with
>> Lyndon Ong, George Newsome and Rajender Razdan of Ciena about ITU
>> networking recommendations.  This was extremely helpful, and I thank
>> the Ciena folks very much for their time and help.
>>
>> The following notes are put together by Jeroen and myself - please
>> feel free to add or correct or question.
>>
>> We spend the first part of the meeting going over slides (see
>> attachnment below) describing NSI concepts in G.800 terms.  It is
>> worth noting that George described the evolution of the
>> recommendations as G.805 describing connection oriented networks, G.
>>  809 attempting to extent that to connectionless networks, and then
>> G. 800 which combines both.  He also commented that the way that
>> G.800 came to be is that "G.805 was observed to be insufficient for
>> describing packet-switched networks (especially ethernet).  Updating
>> a standard is hard, hence a new standard."   So using G.800 concepts
>> is what is done in the slides and in discussions we have had earlier
>> on the mailing list.
>>
>> G.8080 unfortunately still uses G.805 terminology, and adds some more
>>  - but is in the process of being updated/reviewed.  G.8080 is also
>> called ASON.
>>
>> _______________________________________________ nml-wg mailing list 
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>>
>>
> 
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Victor Reijs, Network Development Manager
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