in src/main/java/org/apache/cassandra/distributed/shared/NetworkTopology.java [105:120]
public static NetworkTopology build(String ipPrefix, int broadcastPort, Map<Integer, DcAndRack> nodeIdTopology)
{
final NetworkTopology topology = new NetworkTopology();
for (int nodeId = 1; nodeId <= nodeIdTopology.size(); nodeId++)
{
String broadcastAddress = ipPrefix + nodeId;
DcAndRack dcAndRack = nodeIdTopology.get(nodeId);
if (dcAndRack == null)
throw new IllegalStateException("nodeId " + nodeId + "not found in instanceMap");
topology.put(addressAndPort(broadcastAddress, broadcastPort), dcAndRack);
}
return topology;
}