else {
transport = new DefaultTcpTransportMapping((TcpAddress)listenAddress);
}
snmp = new Snmp(dispatcher, transport);
snmp.getMessageDispatcher().addMessageProcessingModel(new MPv1());
snmp.getMessageDispatcher().addMessageProcessingModel(new MPv2c());
snmp.getMessageDispatcher().addMessageProcessingModel(new MPv3());
USM usm = new USM(SecurityProtocols.getInstance(),
new OctetString(MPv3.createLocalEngineID()), 0);
SecurityModels.getInstance().addSecurityModel(usm);
snmp.listen();