23 Feb
2012
23 Feb
'12
2:23 p.m.
W dniu 2012-02-22 22:50, Freek Dijkstra pisze: > 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 Yes but I would make this more general and say - just different layers. They could be abstractions or tech layers (I'm thinking that layers may be also a good solution to control publishing information by configuring somehow that only some layers can be distributed, others not; a single abstraction could be split into more layers because of some reasons; it would be up to the implementation) > - how these different descriptions should be tied together. Should we > define a relation between them? I think so. The work on examples will help to progress. Roman > 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 > _______________________________________________ > nml-wg mailing list > nml-wg@ogf.org > https://www.ogf.org/mailman/listinfo/nml-wg