[Nsi-wg] NSI naming

[John Vollbrecht]

On May 12, 2009, at 9:24 AM, Martin Swany wrote:

> Hi Jeroen,
>
> I'm (re-?) adding Jason to the cc list as he's right in the middle of
> this discussion as well.
>
> I would add that I think that we are all very close on the way in
> which things are related, which gives rise to layers/levels of
> the network.  I think that the "Relation" element that we're using
> in UNIS (perfSONAR/DCN) land really makes the expressions
> there start to look like the RDF 3-tuples in a way.  While that  
> problem
> is hard, I think that we've been inching closer to having a common
> solution framework.
>

I think the relation might work for this if it is defined -- but still  
it is complicated and important to agree on.  See comment below.


> best,
> martin
>
> On May 12, 2009, at 4:13 AM, Jeroen van der Ham wrote:
>
>> Hi,
>>
>> I think Martin's analysis of your description is correct.
>> I only want to add that you seem to be contradicting yourself  
>> regarding layering, and I think it is very important that we clear  
>> that up.
>>
>> Before I begin, I want to clear something up:
>> Networks transport data by encapsulating it in different layers. I  
>> think we can all agree on that analysis, and we all know what  
>> layers are in general. Therefore I don't want to complicate this  
>> (already complex) discussion by introducing yet another term (i.e.  
>> "level").
>>
>> Then on to your analysis: in the beginning you say that NSI wants  
>> to describe links at a certain layer going over links at a lower  
>> layer. Then later on you say that NSI operates at a single layer  
>> for a particular request.
>>
>> Current networks operate at multiple layers (Ethernet, SONET,  
>> Lambda, etc.). Therefore, if the NSI wants to be able to provision  
>> services across these networks, then it will have to handle  
>> multiple layers.
>>
>> Please realise that the NML is currently describing a layer-less  
>> model. Layers are not part of the model and we are only describing  
>> the general things that are part of every layer. So NML is  
>> currently not able to describe that links at one layer run over a  
>> link at a lower layer.
>>
>> As Martin said, describing layers, and the adaptations between them  
>> is a very very hard problem. One that the NML group will be taking  
>> on soon though.
I agree this is hard.  I think levels and layers are different.   
Layers apply to protocol layers.  I may misuse the term.  Levels for  
me apply to what can be switched for a given topology.  I.e. A given  
topology allows VLANS to be created ete, by concatenating VLANS at  
each edge point.  The VLANS to be switched are carried on something  
else - SONET trunks, GOLEs, Ethernet trunks, etc.  Level in this case  
refers to VLANs on  one level and what carries them on the other.

>>
>>
>>
>> Jeroen.
>

John Vollbrecht
Senior Network Engineer, Internet2
office 734 352 4960 cell 734 395 7890