Modeling interfaces in SysML

[mse]

While the technique for modeling interfaces via ports and interface blocks, along with nested ports, and decomposing ports is clear to me, I am not sure on the best practice for separating physical and logical aspects. Here is what I mean:

Suppose you model two blocks, each with a port representing an Ethernet connection. Now we all know it's for Ethernet traffic. However, depending on who you ask, you might get get a model of a port which shows the pins of the RJ45 connector. Another might just show a port typed by an interface block representing Ethernet packets that can flow in and out of the port. Different abstractions from people with different concerns.

I have seen in the literature the allocation of a connection to another connection, but it seems like this is double work. Perhaps it is necessary however, I am not sure. Does anyone have advice on how to separate concerns here?

One possible solution that came to mind, is that if someone models it with pins and all, then the item flows could be the packets themselves.

[PDC]

For me it partly depends on the requirements for your model. i.e. do your stakeholders need you to be able to present the logical view and the physical layers separately? In that case, it is normally going to be easier to model both Ports separately and, as you suggest, draw the traceability between them - e.g. using 'Allocate'. However, if your stakeholders are less bothered about that (or don't understand the question) then maybe you can [cut some corners and] somehow model both layers using a single Port. My personal preference is to keep the functional, logical and physical views separate in the model - so I would have a logical Port and a physical Port in your scenario.

I also sometimes find that 'nested' Ports are useful in this context.

You mention the 'literature' - maybe you have already read this paper but I think it's a good discussion on a related subject: https://www.omgsysml.org/A_modeling_pattern_for_layered_system_interfaces-INCOSE%20IS15_paper-sarrel-shames.pdf