Hello all, I my opinion one of the main problems that has held up progress in the NSI working group has been our failure to agree on a clear set of NSI requirements for network modelling. I think we have agreed that these should be a minimal set of extensions to the existing NML model, so this should not be a very large set of requirements. What has happen is that many alternative proposals for network models have been suggested, without first clearly identifying and agreeing a set of requirements. I think this has been back-to-front, first we should identify the requirements, and then a group of modelling experts should come up with a proposal for NML extensions. So with this new approach in mind, I would like to kick of a discussion on what the essential requirements NSI has for network modelling. These should only include requirements that go beyond the functions that are already supported in the current NML definition. I suggest the following 10 requirements as a starter: Requirement 1: The model should be able to describe a grouping of network resources that are owned and controlled by a single provider or NSA. (I will call this a NETWORK for the moment) Requirement 2: The model should be able to describe a grouping of NETWORKs. (e.g. a federation of providers with shared policy) Requirement 3: The model should be able to describe resources (ports/points) in a NETWORK that are available for connecting to other NETWORKs. (I will call this a network connection point NCP for the moment) Requirement 4: These NPs should be able to be performed at the end of a link that is internal to the domain as well as to ports on a device. (in my opinion the NCP on a link requirement needs a use-case) Requirement 5: The model should be able to describe an arbitrary number of layers of logical ports within a NCP. Requirement 6: The model should be able to describe connectivity between NETWORKs. (I will call this inter network connection (INCs) for the moment) Requirement 7: The model should be able to describe groups of INCs. Requirement 8: The resources that make up INCs should have ownership by a clearly identifiable provider. (i.e. resources without NSA ownership are not allowed). (note: Does this also include the patch cord between providers?) Requirement 9: The model should allow policy to be assigned to INCs, even where the INC is wholly or partly made up of passive resources. Requirement 10: The model should be able to fully describe a circuit (i.e. NSI service) that transits the topology. Any thoughts on these and other requirements would be helpful. Guy -----Original Message----- From: Freek Dijkstra [mailto:Freek.Dijkstra@sara.nl] Sent: 22 February 2010 13:52 To: NSI WG Cc: Guy Roberts; Jeroen van der Ham; John Vollbrecht Subject: Re: [Nsi-wg] NML topology Can I summarize this discussion as follows? Requirement: It should be possible to assign a policy to an (interdomain) link. Of course, I can think of a solution (e.g. make that link part of a topology, like John's second picture, assign the topology to a networkdomain, and assign a policy to that networkdomain). However, this seems out of scope. I think the best way forward is to describe this and other requirements and forward them to the NML and ask the NML folks to come up with a solution for the requirement. I also wholeheartedly invite all NSI group members to become a "NML folk" too by joining the NML list! Regards, Freek