This has been a good discussion. The issues brought up so far are (and my take based on responses as well as my own opinion) : 1. In Topology representation, is there a need to differentiate a GOLE from a Network/Domain? - the consensus seems to be a "No". It seems that topologically there is no difference between a GOLE and a Domain 2. I need to include a particular domain? How do I specify that to the path computing engine in NSI? - The inclusion of domains can be done via the same concept as an ERO. You can ask for a partial ERO that puts those particular path constraints on the path computation decision. You could specify that you want to use a particular GOLE using a partial ERO. NSI should support asking for paths with EROs specified (which version up for discussion) 3. There may be different policies associated with a particular network (domain, link, open-exchange, etc). How and where does that have bearing on the whole path computation process? - In the tree/chain model, each network domain being transitioned has the need to do their own intra-domain path computation. In order to do that, it has to apply the policies of the domain. The Service Plane architecture allows many different points in the reservation process to apply local policies. The first is when a user sends a service request to a NSA Provider Agent. The agent can apply policies based on egress/ingress ports requested through that domain and accept/ reject the connection. Similarly the PCE model allows for a series of decisions to take place based on constraints till a workable alternative is clear. Distributing policies of links/connections between domains is inherently a very complex process and should be avoided. I would rather we focus on network capabilities instead. Inder On Jun 28, 2010, at 5:56 AM, Freek Dijkstra wrote:
Gigi Karmous-Edwards asked:
So, how is this modeled? Victor suggests having the link between two GOLEs as a single domain?
This is a good approach IMHO. It allows one to add a policy to a link. And as Erik-Jan eloquently pointed out, a link can have a policy.
I think the key question that started this debate was: Are GOLEs significantly different from Domains such that we need to model them differently?
Bearing the KISS principle in mind: If they can be modeled the same way for path finding, then I would do so. That would make the architecture more simple, and thus more powerful.
I have not yet seen a compelling reason to model them differently. Such reason might still be there (I can imagine that it would speed up things knowing beforehand that a GOLE has no internal bottlenecks or is policy free.), however, I have not seem a simulation to prove that.
Regards, Freek
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