  Link failures and cable miswirings are not uncommon in building data center
networks, which prevents the existing automatic address configuration methods
from functioning correctly. However, accurately detecting such malfunctions is
not an easy task because there could be no observable node degree changes.
Fixing or correcting such malfunctions is even harder as almost no work can
provide accurate fixation suggestions now.
  To solve the problems, we design and implement A3, an automatic
topology-aware malfunction detection and fixation system. A3 innovatively
formulates the problem of finding minimal fixation to the problem of computing
minimum graph difference (NP-hard) and solves it in O(k^6) and O(k^3) for any
less than k/2 and k/4 undirected link malfunctions for FatTree, respectively.
Our evaluation demonstrates that for less than k/2 undirected link
malfunctions, A3 is 100% accurate for malfunction detection and provides the
minimum fixation result. For greater or equal to k/2 undirected link
malfunctions, A3 still has accuracy of about 100% and provides the near optimal
fixation result.
