Jerry Sobieski wrote:
Exactly. I view a topology as [initially] an abstract domain that comprises a comprehensive but finite switching function between points at its boundary. We can map those points to co-registered points in another topology that expresses some other aspects - perhaps geolocation, or internal connectivity, or policy-based capabilities, or a combination thereof. A perfect example would be a simple abstract topology announced publicly that mapsTo a much more detailed internal physical topology that the local network wishes to manage itself. The NSA is the agent that speaks to other NSAs inter-domain (at whatever domain level we are at) and translates as necessary to local agents that do the dirty work internally.
It is important IMO that NML be recursive and abstract in this manner as well as able to capture physical hdw engineering trappings. It looks like it is very close to being able to do this.
NML is partly capable of defining recursive topologies. * It does not dictate till what level a topology should be abstracted, and is designed to make this irrelevant (I recommend to give figure 7 of ITU-T G.800 a good stare: "Example of recursive partitioning") * NML does not yet define how to tie topologies of different abstraction together, other than that all ports at the edge of a the more abstract topology will also be ports at the edge of the less abstract topology, and should (in my view) get the same identifier. A 'mapTo' relation may be a possibility. We played with the concept of virtualisation during OGF 23 in Barcelona (see https://forge.ogf.org/sf/go/doc15482), which does this for nodes (both partitioning a physical node into smaller logical nodes as well as grouping nodes into something that we now call a "topology"). The discussion was resolved by making all concepts: both node and topology abstract. Thinking about it, if nodes in NML are also abstract, perhaps both concepts (topology and node) are the same, only on different levels of abstraction. I like to hear from nml-wg participants: - if they think that NML should be capable of defining a topology at different layers of abstraction - how these different descriptions should be tied together. Should we define a relation between them? For the NSI participants I'm interested in hearing if you think that only NML should define different levels of abstraction, or if you also expect NSNetwork to have different levels of abstraction, and if an NSA have different levels of abstraction. (I presume both have, given that NSA supports a tree-like request structure, where a top-NSA can delegate requests for path provisioning to other NSA). Regards, Freek