[Nml-wg] More UML....

[Jeroen van der Ham]

Aaron Brown wrote:
>> A _Port_ is related to zero or one _Node_, and also has a relation 
>> with zero, one or two  (uni-directional) _Links_.
> Where does an unconnected port exist?

When we define an inter-domain link we typically define a connection to 
an unconnected port and point to the other domain for more information 
about that interface.

But I guess this is also a remnant of us preferring to use a relation 
between interfaces, instead of a link object in between. So I guess we 
could also require that an interface is connected to a node.

What does the rest think?


>> * A _Port_ MAY have a _source_ relation with up to two _Unidirectional 
>> Links_.
>> * A _Port_ MAY have a _sink_ relation with up to two _Unidirectional 
>> Links_.
> Does this mean that a port might be a sink for two unidirectional links? 
> If so, under what circumstances could it occur that a port could be a 
> sink for more than one link, but not more than two?

A Port typically has two uni-directional links to another device, and 
two uni-directional crossconnects (crossconnects are also links). So 
then it has two source relations and two sink relations.

Freek also brought up an example where a SONET switch with an Ethernet 
interface. If you just look at the Ethernet Layer, this would appear as 
a Port with links ("actual link links") to two devices.

Jeroen.