[Nsi-wg] NSI Topology

[John MacAuley]

Comments in line.

On 2013-12-04, at 6:55 AM, Freek Dijkstra <Freek.Dijkstra at surfsara.nl> wrote:

> I'm not clear on the purpose of this type of adaptation (one type
> encapsulated in the same type). Can you perhaps give a example?

Jerry brought this specific Ethernet example up, and I read through the standards to verify.  The Q-in-Q double label is a single instance of the more generic 2..N label stacking supported by the standards.  Jerry has the requirement to allow for an arbitrarily number of labels to be pushed and popped as the Ethernet packet transits the network.  In this specific example, the packet arrives on one port in the domain, is a label is added, and it leaves another port in the domain with the same encoding.  Somewhere else in the network the labels will be popped an equivalent number of times.

> 
> (slide 5)
> What is the purpose of having different Service Domains in a Network
> Topology? Because the STP in each services domain are of a different
> type? Or to describe geographic subdivisions withing a Network Topology?

The definition of a Service Domain is that it contains STPs that can be connected without restriction.  When STP are of different types then they must be in different service domains.  In fact, if a network does not support label swapping then each STP with the same label value will be grouped in their own Service Domain.

> 
> Note that the former is represented in NML using multiple
> SwitchingServices, and the later is represented in NML using multiple
> (sub) Topologies 'in' a larger Topology (where this 'in' is formally
> defined as a 'hasTopology' relation).

I understand the distinction.

> 
> PS: I now see that you answered this on slide 19. Thanks, John! I love
> this proposal. My head is too blurred to due lack of sleep to really
> grok every character in the example, but from a first look, it looks
> very, very good!

Thank you kind sir!
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