2010年下半年 网络工程师 上午试卷(11)

　　● 网络系统设计过程中，逻辑网络设计阶段的任务是　(69)　。

　　(69)A.依据逻辑网络设计的要求，确定设备的物理分布和运行环境

　　B.分析现有网络和新网络的资源分布，掌握网络的运行状态

　　C.根据需求规范和通信规范，实施资源分配和安全规划

　　D.理解网络应该具有的功能和性能，设计出符合用户需求的网络

　　参考答案：

　　(69)D

　　● 利用SDH实现广域网互联，如果用户需要的数据传输速率较小，可以用准同步数字系列(PDH)兼容的传输方式在每个STM-1帧中封装　(70)　个E1信道。

　　(70)A.4 B.63 C.255 D.1023

　　参考答案：

　　(70)B

　　● The metric assigned to each network depends on the type of protocol.Some simple protocol, like RIP, treats each network as equals.The 　(71)　 of passing through each network is the same;it is one 　(72)　 count.So if a packet passes through 10 network to reach the destination, the total cost is 10 hop counts.Other protocols, such as OSPF, allow the administrator to assign a cost for passing through a network based on the type of service required.A 　(73)　 through a network can have different costs(metrics).For example, if maximum 　(74)　 is the desired type of service, a satellite link has a lower metric than a fiber-optic line.On the other hand, if minimum 　(75)　 is the desired type of service, a fiber-optic line has a lower metric than a satellite line.OSPF allow each router to have several routing table based on the required type of service.

　　(71)A.number B.connection C.diagram D.cost

　　(72)A.process B.hop C.route D.flow

　　(73)A.flow B.window C.route D.cost

　　(74)A.packet B.throughput C.error D.number

　　(75)A.delay B.stream C.packet D.cost

　　参考答案：

　　(71)D，(72)B，(73)C，(74)B，(75)A