超星 - chapter 1 written exercise update - 查题吧

简答题

3. Suppose a 1 Gbps link has exponential packet interarrival time and service time. We like to apply the queuing theory and Little’s result to calculate mean latency and occupancy.a. If the mean arrival rate is 500 Mbps, what are the mean latency, queuing time, and occupancy?b. If the link bandwidth and mean arrival rate are increased by an order of magnitude to 10 Gbps and 5 Gbps, respectively, what are the mean latency, queuing time, and occupancy?3．假设有一条1Gbps的链路，具有指数级的数据包到达间隔时间和服务时间。我们想运用排队论和Little结论来计算平均等待时间和平均占用时间。a.如果平均到达速率是500 Mbps，则平均延迟，排队时间，占用时间各是多少？b.如果链路带宽和平均到达速率分别增加幅度为10Gbps和5Gbps，则平均延迟，排队时间，和占用时间分别是多少？

简答题

4. If 30% of packets have a size of 64 bytes, 50% of packet has a size of 1500 bytes, and the rest have a size uniformly distributed between 64 and 1500 bytes, what is the maximum number of aggregated packets per second (pps) at a router with 12 links each of 10 Gbps?4．如果30％数据包的大小为64字节，50％分组的大小1500字节，其余的大小均匀分布在64和1500字节之间，则在一台拥有12条10Gbps链路的路由器上每秒汇聚数据包的最大数量（PPS）是多少？

简答题

5. Suppose there are 3,000,000 new phone call arrivals per minute to the switched telephone system worldwide, with each call lasting for 5 minutes on average, and there are 6 hops (i.e. 6 links and 6 nodes) on average between the callers and callees. How many memory entries are occupied on average to support the switched connectivity worldwide?5．假设每分钟有300万个新的电话呼叫到达全球范围的电话交换系统，平均每次通话长达5分钟，并且每个呼叫用户和被叫用户之间平均有6跳（即6条链路和6个节点）。那么为了支持全球交换连接平均需要占用多少内存表项？

简答题

6. In a clustering of 4,294,967,296 nodes, if we still want to keep the three-level hierarchy like the one in Figure 1.1，but like to have the same number of group members, groups, and supergroups at the group, supergroup, and “super-supergroup” levels, respectively, what is that number approximately?6．在一个拥有4,294,967,296个节点的集群中，如果仍然要保持像图1.1中所示的三个层次，但仍希望有相同数量的组成员和组，组上的超群组，超组，以及“超超组”层，那么近似的数量是多少？

简答题

7. If, due to the shortage of IP addresses, we halve the size at the group and the supergroup levels in Figure 1.1, with at most 128 group members for a group and 128 groups for a supergroup, how many supergroups can we allow?7．如果由于IP地址短缺，我们将图1.1中的组和超组一分为二，每组最多有128个成员每个超组最多有128个组，则最多允许多少这样的超组？

简答题

8. Compare the differences in the requirements and principles for data communications and tele(voice)communications. Name the three most important differences and explain.8．比较数据通信和电信（语音）通信的要求和原则之间的差异。对最重要的三个差异进行命名并加以解释。

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