  Hella et al. (PODC 2012, Distributed Computing 2015) identified seven
different models of distributed computing - one of which is the port-numbering
model - and provided a complete classification of their computational power
relative to each other. However, one of their simulation results involves an
additive overhead of $2\Delta-2$ communication rounds, and it was not clear, if
this is actually optimal. In this paper we give a positive answer: there is a
matching linear-in-$\Delta$ lower bound. This closes the final gap in our
understanding of the models, with respect to the number of communication
rounds.
