A somewhat related issue on source/sink. I don't think this was ever written down. Freek Dijkstra wrote:
The question at hand is basically how to describe the following (with apologies with my poor ASCII art skills)
port A link X port B link Y port C O------------------>O------------------>O
[...]
In the NML schema it is currently defined as:
link X relation=source port A relation=sink port B link Y relation=source port B relation=sink port C
For the record, an alternative way to describe this is making the ports leading instead of the links: port A relation=egress link X port B relation=ingress link X relation=egress link Y port C relation=ingress link Y Technically I think these are equivalent: the provide a directed relation between links and ports. Which one is syntactically better depends what is more common, a one-to-many or a many-to-one relation between ports and links. For the circuits, this is often a one-to-one relation. Since we implemented cross-connects as links, VLANs are likely also described as some kind of "link", but one with multiple sources and sinks. Hence, there is a one to many relation from link to port. This means that the source and sink relation we have now is more easy to convey in XML than the alternative ingress and egress relation. I personally think the source/sink stuff is still the best alternative we have. Regards, Freek