Preparing for tomorrow’s Computer Networking(A Top-Down Approach) exam 1

Tomorrow morning will be my exam for Computer Networking(A Top-Down Approach).

I coded lots of applications related with netwroking, whatever for small embedded server or large-scale high concurrency server, whatever TCP based or UDP based, including but not limited to ICMP, HTTP, FTP, SMTP, RTSP, RTP, SIP protocols.

I was so sure about this course once, but after attended this course then I found out that this is really different than what I thought, especially when I got the exercise materials. Because what I did is only the TOP rather than TOP-DOWN, although I don’t think I gonna get into the DOWN level in the furture(This is at least I’m thinking now). And what I’m familiar with is network programming, theoretical stuffs? Oops, no!

So I have to do more for passing this course.

There will be 5 big problems I need to get deep into, and here are the list, just for memo:

1. 距离适量(DV)路由选择算法(P144)

网络拓扑与边的当前代价如下图所示,节点E与A、B、D相邻。经过实测节点E到A、B、D的代价分别为1、8、2,节点E从A、B、D分别接收到的距离矢量如右下图所示,使用距离矢量(DV)算法,计算出节点E更新之后的路由表(表的结构是: 目标节点、下一跳、代价估计),并给出计算过程。

 image002    来自目标 A B D
A 0 6 3
B 6 0 3
C 5 1 2
D 3 3 0
E 1 8 2

2. 信道利用率(channel utilization)计算(P242)


1.如果采用停止等待协议(stop and wait protocol),信道的利用率是多少?

如果采用管道协议(pipeline protocol ),为了能够时信道的利用率达到100%,发送窗口的尺寸最少应该是多少?

3. CRC计算,包括源端编码和目标端解码

4. CDMA原理及其计算

5. 安全电子邮件的过程(报文摘要、源端、目标端过程)

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