calculateBroadcastTreeInClusters();
for(Cluster c: clusters) {
// c.id is the smallest node that's in the cluster
BroadcastTree tree = clusterBroadcastTrees.get(c.id);
//log.info("Broadcast Tree {}", tree);
Set<NodePortTuple> nptSet = new HashSet<NodePortTuple>();
Map<Long, Link> links = tree.getLinks();
if (links == null) continue;
for(long nodeId: links.keySet()) {
Link l = links.get(nodeId);
if (l == null) continue;
NodePortTuple npt1 = new NodePortTuple(l.getSrc(), l.getSrcPort());