【作者】 江山；

【导师】 张为群；

【作者基本信息】 西南师范大学 ， 计算机应用技术， 2004， 硕士

【摘要】 主动网络(Active Networks)的概念是DARPA(Defense Advanced Research Projects Agency)研究协会于1995年，针对当时网络发展过程中遇到的几个问题(即，把新的技术和标准引入现有网络中的困难：由于几个网络协议层的冗余操作而使网络性能下降；在已存在的结构模块中加入新服务的困难)提出的。 主动网络是相对于现有的网络比较而言的。现有的网络由于不对报文进行处理或计算，因此可以称之为被动网络(Passive Networks)。虽然在现有的网络中路由器和交换机也可以改变报文的报头，但它们对真正的用户数据却不做任何处理，原封不动地转发用户数据是它们的宗旨。即使对报头的改变和相关路由处理也是独立于用户处理和产生这些报文的应用程序的。相比之下，在主动网络中的路由器和交换机则可以对网络报文进行用户自定义计算。 可编程主动网络语言(PLAN)采用集成思想来实现主动网络的特点。PLAN程序被集成到每一个数据包，然后发送到网络，每一个消息或包都要求包含一个程序段，说明是否可能嵌入数据。当这些包到达主动结点时，主动结点将解释这些程序，然后将程序的嵌入数据发出。 当前的PLAN网络以SLRP(SLRP-Service Level Routing Protocol)路由协议作为默认路由服务，该协议是基于跃点(hops)计数的一个动态路由协议。面对现实网络系统中各种复杂的链路形态，仅仅基于跃点计数的路由算法是低效和片面的。 因此，在本文中提出了一个基于PLAN网络的现有架构，以开销(cost)代替跃点(hops)计数计算网络路径长度，实现最短路径优先(Shortest Path First，SPF)路由规则的主动网络模型。该模型充分利用主动网络的可编程特性，在不修改低层网络协议的情况下，以服务的方式动态加载路由协议，并通过PLAN主动包加以调用，来实现最短路径优先的路由规则。 整个模型由Java和Pi zza程序语言编写，并由PLAN语言进行安装和服务的调用，最后通过Ping和Traceroute这两个常用的网络实用程序进行实例化分析和测试。更多还原

【Abstract】 Because of contraposing to serials of problems in the development of network (viz., the difficulty of importing new technologies and standards into current network, the decline of network performance because of redundancy operations by few net protocol layers, the difficulty of joinning new services in existing structure modules), the concept of AN(Active Networks) is presented by DARPA(Defense Advanced Research Projects Agency) in 1995.AN is compared to current network. Current network be named as Passive Networks because they don’t compute or disposal message. Although the routers and the switchs can change the header of message in current network, they do nothing about the actual user data, and their tenet is transmiting user data without change. Even if changing the header of message and other route operation is independent of user disposal and applications which made these message. Compare to this, the routers and the switchs in AN can compute network message according to users’ demands.PLAN(Programming Language for Active Network) implement the characters of AN via idea of integration. Program is integrated in each data packet, then be send to network. Every message or packet have a piece of program code, which explain whether it can embed data or not. Active node will explain these program, and send out data in program when the packet arrived.Current PLAN network use SLRP (SLRP-Service Level Routing Protocol) route protocol as its default route service. This protocol is a dynamic route protocol based on hops counting. Its arithmetic just based on hops counting is low efficiency and unilateralism when the network have complex link state.We presented an AN model in this article. It based on the current structure of PLAN network, which use cost to instead of the hops to compute network path length and realize the route rule of Shortest Path First (SPF). This model make full use of the programmable feature of AN, dynamicly install the route protocol as a service without reworking bottom protocol of network, and implement the route rule of the SPF by PLAN active packet.The model is written by Java and Pizza program language. It was installed and debugged by PLAN language, and analyzed and tested by Ping and Traceroute program which are common network utilities.更多还原