[Nsi-wg] NML topology

[Freek Dijkstra]

John Vollbrecht wrote:

> A NSI network can be describe as a NML group specifically owned by an  
> NRM - I don't think there is any problem with this.  Nodes and links  
> can have owners in NML.

Note that NML now avoids the word "network" because it is unclear
whether the operational grouping or administrative grouping is meant.
The NML terminology is as follows:

Topology: A set of Network Elements and the links connecting them.

NetworkDomain: An unordered collection of Network Elements managed under
the same shared policy umbrella.


> So - the proposal so far is to call the edge of a network a port

In NMC this is called the demarcation point.

I don't thing this concept is yet defined in either NSI or NML, but I
propose to re-use this existing name.

> This is a problem because NML  
> links don't have ports, so the proposal is to allow links to have ports.

I'm confused here. NML does indeed define ports, they are logical
interfaces. In the current definition, they are the things that "connect
a Node or a Group to the rest of the network", presumably connecting the
Node or Group to a Link.

> How this helps is that now topology for pathfinding can be described  
> between nodes over links without worrying about ownership, and  
> reservation can be done using resources without worrying about  
> topology between networks.

Could you elaborate on your specific requirement? While I think this is
correct, I was under the impression that this was already possible.



Aslo

D 3.3: The model must be able to describe resources (ports/points) in a
Network that are available for connecting to other Networks.  (this is a
Network Port)

As a last note, you refer to ports and owners in this document. I just
had a quick look at the NSI requirement document
(https://docs.google.com/Doc?docid=0AZTOJNVUoixhZGZ4cjRiemtfMzQyaGZtOG4yZ2o&hl=en)
This document has three design statements related to ports:

> D 3.3: The model must be able to describe resources (ports/points) in
> a Network that are available for connecting to other Networks.  (this
> is a Network Port)I think the *requirement* is that the model must
> indicate where topologically networks transport planes interconnect.
> We need to come to a vote/consensus on a model to adopt.  This
> requirement (and many of these) sound more like definitions than
> requirements. -Jerry Sobieski 2/26/10 10:18 AM
> 
> D 3.4: Network Ports must be able to be assigned to the end of a link
> that is internal to the domain as well as to ports on a device.  In
> my opinion a Network Port on a link requirement needs a use-case -Guy
> Roberts 2/26/10 3:17 PM  Sounds like a definition rather than a
> requirement-Jerry Sobieski 2/26/10 10:21 AM
> 
> D 3.5: The model must be able to describe an arbitrary number of
> layers of logical ports within a Network Port. Must be able to
> describe multi-layer networks.

and there is one design statement related to owner:

> D 3.8: The resources that make up Network Points must 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?) All "resources" in the NSI model *must* map
> to a single authoritative management agent (NSA). -Jerry Sobieski
> 2/26/10 10:31 AM

In line with these (inline) comments, a clear requirement would be more
beneficial for the NML instead of a definition proposal.

For example, I like the requirement on ownership, since it clearly
requires a relation between network point and owner, and defines that
each network point MUST have exactly one owner. Now all I like to know
if this "owner" defines the entity that either *decides* OR *enforces*
the policy, and if these may be different entities.

If the requirement for Port would be just as clear, I would be very happy.

Regards,
Freek