为什么我的WCF频道失败了?

我有一台计算机,它运行一个程序,在另外4台计算机上管理多达48个单独的进程。我已将WCF服务(每个进程一个)设置为:

    public void StartService(Uri uri, string identifier)
    {
        unitMetaData = identifier;
        var binding = new WSDualHttpBinding(WSDualHttpSecurityMode.None);
        binding.ReliableSession.InactivityTimeout = TimeSpan.FromDays(20);
        var reader = binding.ReaderQuotas as XmlDictionaryReaderQuotas;
        reader.MaxStringContentLength = WCFContentSize; // 16777216
        service = new ServiceHost(this, uri);
        service.Faulted += TestService_Faulted;
        service.AddServiceEndpoint(
            typeof(IController),
            binding,
            identifier);
        service.Open();
    }

以下是远程进程的代码:

    public void Connect()
    {
        // External binding used to change the WCF XML text content size
        var binding = new WSDualHttpBinding(WSDualHttpSecurityMode.None);
        binding.ReliableSession.InactivityTimeout = TimeSpan.FromDays(20);
        var reader = binding.ReaderQuotas as XmlDictionaryReaderQuotas;
        reader.MaxStringContentLength = WCFContentSize; // 16777216
        DuplexChannelFactory<IController> factory = new DuplexChannelFactory<IController>(new InstanceContext(this), binding);
        controllerChannel = factory.CreateChannel(new EndpointAddress(controllerAddress, new DnsEndpointIdentity(controllerAddress.DnsSafeHost), new System.ServiceModel.Channels.AddressHeaderCollection()));
        ((IClientChannel)controllerChannel).OperationTimeout = TimeSpan.FromSeconds(ChannelOperationTimeoutInSeconds); // 300
        controllerChannel.RequestTestData();
    }

An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is:
System.ServiceModel.CommunicationObjectFaultedException: The communication object, System.ServiceModel.Channels.ServerReliableDuplexSessionChannel, cannot be used for communication because it is in the Faulted state.

Server stack trace: 
   at System.ServiceModel.Channels.TransmissionStrategy.WaitQueueAdder.Wait(TimeSpan timeout)
   at System.ServiceModel.Channels.TransmissionStrategy.InternalAdd(Message message, Boolean isLast, TimeSpan timeout, Object state, MessageAttemptInfo& attemptInfo)
   at System.ServiceModel.Channels.ReliableOutputConnection.InternalAddMessage(Message message, TimeSpan timeout, Object state, Boolean isLast)
   at System.ServiceModel.Channels.ReliableDuplexSessionChannel.OnSend(Message message, TimeSpan timeout)
   at System.ServiceModel.Channels.DuplexChannel.Send(Message message, TimeSpan timeout)
   at System.ServiceModel.Dispatcher.DuplexChannelBinder.Request(Message message, TimeSpan timeout)
   at System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
   at System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
   at System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)

Exception rethrown at [0]: 
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
   at SEL.MfgTestDev.ESS.ServiceContracts.ITestProcessClient.Ping()
   at SEL.MfgTestDev.ESS.Testing.Service.TestService.Ping() in C:\Projects\Mfg_TestDev_ESS_Rev3\branches\MSU-5-18-2010\ESS.Testing.Service\TestService.cs:line 349

怎么回事?为什么它突然变成了故障状态。有什么方法可以让我知道连接出现故障的原因吗?