  The popular Physarum-inspired Algorithms (PAs) have the potential to solve
challenging network optimization problems. However, the existing researches on
PAs are still immature and far from being fully recognized. A major reason is
that these researches have not been well organized so far. In this paper, we
aim to address this issue. First, we introduce Physarum and its intelligence
from the biological perspective. Then, we summarize and group four types of
Physarum-inspired networking models. After that, we analyze the network
optimization problems and applications that have been challenged by PAs based
on these models. Ultimately, we discuss the existing researches on PAs and
identify two fundamental questions: 1) What are the characteristics of Physarum
networks? 2) Why can Physarum solve some network optimization problems?
Answering these two questions is essential to the future development of
Physarum-inspired network optimization.
