本文探讨了第七层开放系统互连应用层的服务并将其与第三、四层交换服务进行了比较。了解了高层交换到底是什么东西以后，你在做下一个网络升级的预算时就可以驾轻就熟了。 诸如 Ｃｉｓｃｏ、Ｅｎｔｅｒａｓｙｓ（将并入 Ｃａｂｌｅｔｒｏｎ麾下），Ａｖａｙａ（Ｌｕｃｅｎｔ负 This article explores the service at the seventh floor of the open system interconnect application layer and compares it with the third and fourth floor exchange services. After you understand what high-level exchange is in the end, you can be familiar with the budget for the next network upgrade. Such as Cisco, Enterasys (will be incorporated under Cabletron), Avaya (Lucent negative