/**
   * Event handler called when a switch leaves the network.
   *
   * @param DPID for the switch
   */
  @Override
  public void switchRemoved(long switchId) {
    IOFSwitch sw = this.floodlightProv.getSwitch(switchId);
    log.info(String.format("Switch s%d removed", switchId));

    /** ****************************************************************** */
    /* TODO: Update routing: change routing rules for all hosts */
    // check
    for (Host host : this.getHosts()) {
      OFMatch matchCriteria = new OFMatch();

      matchCriteria.setDataLayerType(OFMatch.ETH_TYPE_IPV4);
      matchCriteria.setNetworkDestination(host.getIPv4Address());

      for (IOFSwitch currSw : this.getSwitches().values()) {
        SwitchCommands.removeRules(currSw, this.table, matchCriteria);
      }
      updateAllRouting();
    }
    /** ****************************************************************** */
  }
  private void installL3FwdRule(IOFSwitch currSw, Host host, int opPortTowardsSrc) {
    if (debug_level < 2)
      System.out.println(
          "L3 Install Rule :  sw - "
              + String.valueOf(currSw.getId())
              + " port "
              + opPortTowardsSrc);
    OFMatch matchCriteria = new OFMatch();
    matchCriteria.setDataLayerType(OFMatch.ETH_TYPE_IPV4);
    matchCriteria.setNetworkDestination(host.getIPv4Address());

    List<OFAction> actionOps = new LinkedList<OFAction>();
    OFActionOutput actOp = new OFActionOutput(opPortTowardsSrc);
    actionOps.add(0, actOp);
    OFInstructionApplyActions applyActions = new OFInstructionApplyActions(actionOps);
    List<OFInstruction> instructionList = new ArrayList<OFInstruction>();
    instructionList.add(applyActions);

    SwitchCommands.removeRules(currSw, this.table, matchCriteria);
    if (SwitchCommands.installRule(
            currSw, this.table, SwitchCommands.DEFAULT_PRIORITY, matchCriteria, instructionList)
        == false) {
      System.out.println(
          "L3 Rule not installed: sw "
              + String.valueOf(currSw.getId())
              + " port: "
              + opPortTowardsSrc
              + " table: "
              + this.table);
    } else {
      if (debug_level < 2)
        System.out.println(
            "L3 Rule installed : sw "
                + String.valueOf(currSw.getId())
                + " port: "
                + opPortTowardsSrc
                + " table: "
                + this.table);
    }
  }
  /**
   * Event handler called when a host is no longer attached to a switch.
   *
   * @param device information about the host
   */
  @Override
  public void deviceRemoved(IDevice device) {
    Host host = this.knownHosts.get(device);
    if (null == host) {
      return;
    }
    this.knownHosts.remove(host);

    log.info(String.format("Host %s is no longer attached to a switch", host.getName()));

    /** ****************************************************************** */
    /* TODO: Update routing: remove rules to route to host */

    OFMatch matchCriteria = new OFMatch();
    matchCriteria.setDataLayerType(OFMatch.ETH_TYPE_IPV4);
    matchCriteria.setNetworkDestination(host.getIPv4Address());

    for (IOFSwitch currSw : this.getSwitches().values()) {
      SwitchCommands.removeRules(currSw, this.table, matchCriteria);
    }
    /** ****************************************************************** */
  }