[第四章呼叫处理过程.ppt

图7 号码分析结果类型举例 图8 多级表格结构的应用 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 4.3.4 电话网的路由选择 一、路由的含义 路由是在两个交换局之间建立一个呼叫连接或传送消息的途径。它可以由一个电路群组成，也可以由多个电路群经交换局串接而成。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 二、路由选择方案 在等级制通信网中，任何两台交换机之间都可能存在多条路由。因此，必须有一种经济合理的路由选择方案。 选择路由时应充分利用高效直达路由，尽量减少转接次数和尽量少占长途电路。路由选择顺序和原则如下： (1) 先选高效直达路由。当高效直达路由忙时，选迂 回路由，选择顺序是“由远至近” 。 (2) 最后选择最终路由。最终路由可以是实际的最终 路由（低呼损电路），也可以是基干路由。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. 路由选择举例 例 两个地区之间的长途网络结构如下图所示， 假定交换中心A呼叫交换中心B ，试按 “由远至近” 选择顺序依次给出全部路由。 解：根据路由选择顺序和原则，首选直达路由，当直达路由忙时，再选迂回路由，最后选基干路由。 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. * 1.3.3 电话网路由选择方法 等级制选路与无级选路 等级制选路：路由选择是在从源节点到宿节点的一组路由中依次按顺序进行 无级选路：对于从源节点到宿节点的一组路由，路由选择过程中无先后顺序，可以互相溢出且无先后顺序 固定路由与动态路由 固定路由：交换机的路由表一旦生成后相对固定，其改变须人工参与 动态路由：交换机的路由表可以根据时间、状态或事件动态改变 Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd. Evalua