title: Akka not automatically join seed nodes
body: <p>I define an akka cluster with play app.</p>
  
  <p>application.conf</p>
  
  <pre><code>akka {
    actor {
      provider = "akka.cluster.ClusterActorRefProvider"
    }
    remote {
      log-remote-lifecycle-events = off
      netty.tcp {
        hostname = "192.168.1.100"
        port = 2552
      }
    }
    cluster {
      seed-nodes = [
        "akka.tcp://application@192.168.1.100:2552",
        "akka.tcp://application@192.168.1.101:2552",
        "akka.tcp://application@192.168.1.102:2552"]
        auto-down-unreachable-after = 10s
    }
  }
  </code></pre>
  
  <p>Then I define a cluster listener</p>
  
  <pre><code>class ClusterListener extends Actor with ActorLogging {
    def receive = {
      case state: CurrentClusterState =&gt;
        log.info("Current members: {}", state.members.mkString(", "))
      case MemberUp(member) =&gt;
        log.info("Member is Up: {}", member.address)
      case UnreachableMember(member) =&gt;
        log.info("Member detected as unreachable: {}", member)
      case MemberRemoved(member, previousStatus) =&gt;
        log.info("Member is Removed: {} after {}",
          member.address, previousStatus)
      case _: ClusterDomainEvent =&gt; // ignore
    }
  }
  </code></pre>
  
  <p>And start my app like this</p>
  
  <pre><code>val clusterListener = Akka.system.actorOf(Props[ClusterListener], "cluster-listener")
    Cluster(Akka.system).subscribe(clusterListener, classOf[ClusterDomainEvent])
  </code></pre>
  
  <p>I firstly start the app on 192.168.1.100, it joins.</p>
  
  <blockquote>
    <p>Then I start the same app on <code>192.16.1.101</code> and <code>192.16.1.102</code>. </p>
  </blockquote>
  
  <p>But the first seed node never receive a join event!</p>
  
  <blockquote>
    <p>What should I do, to let the other nodes join this cluster ?</p>
  </blockquote>