Hi, if we want to have granular description I prefer second approach. The only concern I would have is that it needs more elements to use and thus is more complicated (but I think it's not a problem as the information based on the schema will be shared and parsed automatically by applications). regards, Roman Freek Dijkstra wrote:
Hi all,
Yet another single layer use case (sorry to procrastinate on the multi layer use case, I want to make sure that single layer is tackled before diving in the hard stuff).
Let's start with a single bidirectional link (= 2 unidirectional links) between two nodes:
----------> Node A Node B <----------
Each Node here has two (unidirectional!) interfaces: Node A hasPort a_out and a_in Node B hasPort b_out and b_in
The relations here are: Node A hasPort a_out Node A hasPort a_in Node B hasPort b_out Node B hasPort b_in a_out source Link A-B b_in sink Link A-B b_out source Link B-A a_in sink Link B-A
So far, so good.
Since we want to model Ethernet, I think we should be able to model broadcast networks. Imagine an old-fashioned LAN:
Node A Node B | | --+-----+-------------+---+-- | | Node C Node D
Again, each Node here has two (unidirectional!) interfaces: Node A hasPort a_out and a_in Node B hasPort b_out and b_in Node C hasPort c_out and c_in Node D hasPort d_out and d_in
Of course each *_out is the egress port, with each *_in is the ingress port.
Now how do I describe this LAN? (A) As a single link, or (B) as multiple links?
Let's first try (A) as a single link:
Node A hasPort a_out Node A hasPort a_in Node B hasPort b_out Node B hasPort b_in Node C hasPort c_out Node C hasPort c_in Node D hasPort d_out Node D hasPort d_in a_out source MyFirstLAN b_out source MyFirstLAN c_out source MyFirstLAN d_out source MyFirstLAN a_in sink MyFirstLAN b_in sink MyFirstLAN c_in sink MyFirstLAN d_in sink MyFirstLAN
But is this correct? Semantically, this would imply that if a_out is sending data, it is also received by a_in.
Let's also try to describe this (B) as multiple links:
Node A hasPort a_out Node A hasPort a_in Node B hasPort b_out Node B hasPort b_in Node C hasPort c_out Node C hasPort c_in Node D hasPort d_out Node D hasPort d_in a_out source LAN_A b_in sink LAN_A c_in sink LAN_A d_in sink LAN_A b_out source LAN_B a_in sink LAN_B c_in sink LAN_B d_in sink LAN_B c_out source LAN_C a_in sink LAN_C b_in sink LAN_C d_in sink LAN_C d_out source LAN_D a_in sink LAN_D b_in sink LAN_D c_in sink LAN_D MyFirstLAN elements {LAN_A, LAN_B, LAN_C, LAN_D}
This later description is closer to the concept of Unidirectional Link as is currently in the schema. The schema further allows grouping to a (Bidirectional) Link. That's what I added on the last line.
What are your preferences?
I see problems with both concepts.
Regards, Freek _______________________________________________ nml-wg mailing list nml-wg@ogf.org http://www.ogf.org/mailman/listinfo/nml-wg