计算机网络自顶向下方法第四版英文版答案资源-CSDN文库

4星 · 超过85%的资源需积分: 35 195 浏览量 2010-04-05 19:31:53 上传评论收藏 2.07MB DOC 举报

《计算机网络自顶向下方法》第四版英文版答案包含了该书的复习问题和习题解答，版本日期为2007年10月29日。这本书是Jim Kurose和Keith Ross合著的《计算机网络：自顶向下方法，以互联网为中心》第四版的配套解决方案，仅供教师使用，不应复制或分发给他人，也不应将其发布在公共网站上。作者保留所有版权。第一章复习问题解答： 1. "主机"和"端系统"这两个词在本书中可以互换使用。端系统包括个人电脑、工作站、Web服务器、邮件服务器、互联网连接的PDA、WebTV等。 2. 这个例子说明了网络通信中的协议和约定的重要性。Alice邀请Bob来参加晚宴的过程类似于网络通信中的交互过程。他们需要通过多次交流确定一个双方都方便的时间，这反映了网络通信中的握手协议和时间同步。 3. 网络程序通常由运行在不同主机上的两个程序组成，它们相互通信。发起通信的程序是客户端，它通常向服务器程序请求并接收服务。 4. 通信方式的不同分类： - 拨号调制解调器通过电话线：适用于家庭用户； - DSL通过电话线：同样适用于家庭用户。这些基本概念在计算机网络中至关重要，它们构成了网络通信的基础。主机和端系统的定义理解有助于我们理解网络中的各个参与者。客户端和服务端的角色定义则揭示了网络服务的请求与提供机制。拨号调制解调器和DSL是早期家庭用户接入互联网的常见方式，展示了技术发展的历程。此外，书中还可能涉及更多章节，如网络层次结构、OSI模型、TCP/IP协议栈、数据传输、错误检测与纠正、网络路由、拥塞控制、网络安全等。每一章都会深入探讨这些领域的原理、协议和技术，帮助读者全面了解计算机网络的工作原理。例如，OSI模型将网络通信分为七层，每层负责不同的功能；TCP/IP协议栈则简化为四层，包括应用层、传输层、网络层和链路层，对应OSI模型的高层部分。在学习过程中，通过解决复习问题和习题，学生能够巩固理论知识，提高分析和解决问题的能力。而这些答案提供了参考，有助于教师评估学生的学习进度和理解程度，同时也可以帮助学生自我检查，确保对每个主题有深入的理解。

资源推荐

资源详情

资源评论

Computer Networking: A Top-Down Approach

Featuring the Internet, 4

Edition

Solutions to Review Questions and Problems

Version Date: October 29, 2007

This document contains the solutions to review questions and problems for the 4th

edition of Computer Networking: A Top-Down Approach Featuring the Internet by Jim

Kurose and Keith Ross. These solutions are being made available to instructors ONLY.

Please do NOT copy or distribute this document to others (even other instructors). Please

do not post any solutions on a publicly-available Web site. We’ll be happy to provide a

copy (up-to-date) of this solution manual ourselves to anyone who asks.

Chapter 1 Review Questions

1. There is no difference. Throughout this text, the words “host” and “end system” are

used interchangeably. End systems include PCs, workstations, Web servers, mail

servers, Internet-connected PDAs, WebTVs, etc.

2. Suppose Alice, an ambassador of country A wants to invite Bob, an ambassador of

country B, over for dinner. Alice doesn’t simply just call Bob on the phone and say,

“come to our dinner table now”. Instead, she calls Bob and suggests a date and time.

Bob may respond by saying he’s not available that particular date, but he is available

another date. Alice and Bob continue to send “messages” back and forth until they

agree on a date and time. Bob then shows up at the embassy on the agreed date,

hopefully not more than 15 minutes before or after the agreed time. Diplomatic

protocols also allow for either Alice or Bob to politely cancel the engagement if they

have reasonable excuses.

3. A networking program usually has two programs, each running on a different host,

communicating with each other. The program that initiates the communication is the

client. Typically, the client program requests and receives services from the server

program.

4. 1. Dial-up modem over telephone line: residential; 2. DSL over telephone line:

residential or small office; 3. Cable to HFC: residential; 4. 100 Mbps switched

Etherent: company; 5. Wireless LAN: mobile; 6. Cellular mobile access (for example,

WAP): mobile

5. HFC bandwidth is shared among the users. On the downstream channel, all packets

emanate from a single source, namely, the head end. Thus, there are no collisions in

the downstream channel.

6. Current possibilities include: dial-up; DSL; cable modem; fiber-to-the-home.

7. Ethernet LANs have transmission rates of 10 Mbps, 100 Mbps, 1 Gbps and 10 Gbps.

For an X Mbps Ethernet (where X = 10, 100, 1,000 or 10,000), a user can

continuously transmit at the rate X Mbps if that user is the only person sending data.

If there are more than one active user, then each user cannot continuously transmit at

X Mbps.

8. Ethernet most commonly runs over twisted-pair copper wire and “thin” coaxial cable.

It also can run over fibers optic links and thick coaxial cable.

9. Dial up modems: up to 56 Kbps, bandwidth is dedicated; ISDN: up to 128 kbps,

bandwidth is dedicated; ADSL: downstream channel is .5-8 Mbps, upstream channel

is up to 1 Mbps, bandwidth is dedicated; HFC, downstream channel is 10-30 Mbps

and upstream channel is usually less than a few Mbps, bandwidth is shared.

10. There are two most popular wireless Internet access technologies today:

a) Wireless LAN

In a wireless LAN, wireless users transmit/receive packets to/from a base station

(wireless access point) within a radius of few tens of meters. The base station is

typically connected to the wired Internet and thus serves to connect wireless users

to the wired network.

b) Wide-area wireless access network

In these systems, packets are transmitted over the same wireless infrastructure

used for cellular telephony, with the base station thus being managed by a

telecommunications provider. This provides wireless access to users within a

radius of tens of kilometers of the base station.

11. A circuit-switched network can guarantee a certain amount of end-to-end bandwidth

for the duration of a call. Most packet-switched networks today (including the

Internet) cannot make any end-to-end guarantees for bandwidth.

12. In a packet switched network, the packets from different sources flowing on a link do

not follow any fixed, pre-defined pattern. In TDM circuit switching, each host gets

the same slot in a revolving TDM frame.

13. At time t

the sending host begins to transmit. At time t

= L/R

, the sending host

completes transmission and the entire packet is received at the router (no propagation

delay). Because the router has the entire packet at time t1, it can begin to transmit the

packet to the receiving host at time t

. At time t

= t

+ L/R

, the router completes

transmission and the entire packet is received at the receiving host (again, no

propagation delay). Thus, the end-to-end delay is L/R

+ L/R

14. A tier-1 ISP connects to all other tier-1 ISPs; a tier-2 ISP connects to only a few of

the tier-1 ISPs. Also, a tier-2 ISP is a customer of one or more tier-1.

15. a) 2 users can be supported because each user requires half of the link bandwidth.

b) Since each user requires 1Mbps when transmitting, if two or fewer users transmit

simultaneously, a maximum of 2Mbps will be required. Since the available

bandwidth of the shared link is 2Mbps, there will be no queuing delay before the

link. Whereas, if three users transmit simultaneously, the bandwidth required

will be 3Mbps which is more than the available bandwidth of the shared link. In

this case, there will be queuing delay before the link.

c) Probability that a given user is transmitting = 0.2

d) Probability that all three users are transmitting simultaneously =

= (0.2)

= 0.008. Since the queue grows when all the users are transmitting, the

fraction of time during which the queue grows (which is equal to the probability

that all three users are transmitting simultaneously) is 0.008.

16. The delay components are processing delays, transmission delays, propagation

delays, and queuing delays. All of these delays are fixed, except for the queuing

delays, which are variable.

17. Java Applet

18. 10msec; d/s; no; no

19. a) 500 kbps

b) 64 seconds

c) 100kbps; 320 seconds

20. End system A breaks the large file into chunks. To each chunk, it adds header

generating multiple packets from the file. The header in each packet includes the

address of the destination: end system B. The packet switch uses the destination

address to determine the outgoing link. Asking which road to take is analogous to a

packet asking which outgoing link it should be forwarded on, given the packet’s

address.

21. Java Applet

22. Five generic tasks are error control, flow control, segmentation and reassembly,

multiplexing, and connection setup. Yes, these tasks can be duplicated at different

layers. For example, error control is often provided at more than one layer.

23. The five layers in the Internet protocol stack are – from top to bottom – the

application layer, the transport layer, the network layer, the link layer, and the

physical layer. The principal responsibilities are outlined in Section 1.5.1.

24. Application-layer message: data which an application wants to send and passed onto

the transport layer; transport-layer segment: generated by the transport layer and

encapsulates application-layer message with transport layer header; network-layer

datagram: encapsulates transport-layer segment with a network-layer header; link-

layer frame: encapsulates network-layer datagram with a link-layer header.

25. Routers process layers 1 through 3. (This is a little bit of a white lie, as modern

routers sometimes act as firewalls or caching components, and process layer four as

well.) Link layer switches process layers 1 through 2. Hosts process all five layers.

26. a) Virus

Requires some form of human interaction to spread. Classic example: E-mail

viruses.

b)Worms

No user replication needed. Worm in infected host scans IP addresses and port

numbers, looking for vulnerable processes to infect.

c) Trojan horse

Hidden, devious part of some otherwise useful software.

27. Creation of a botnet requires an attacker to find vulnerability in some application or

system (e.g. exploiting the buffer overflow vulnerability that might exist in an

application). After finding the vulnerability, the attacker needs to scan for hosts that

are vulnerable. The target is basically to compromise a series of systems by

exploiting that particular vulnerability. Any system that is part of the botnet can

automatically scan its environment and propagate by exploiting the vulnerability. An

important property of such botnets is that the originator of the botnet can remotely

control and issue commands to all the nodes in the botnet. Hence, it becomes

possible for the attacker to issue a command to all the nodes, that target a single

node (for example, all nodes in the botnet might be commanded by the attacker to

send a TCP SYN message to the target, which might result in a TCP SYN flood

attack at the target).

28. Trudy can pretend to be Bob to Alice (and vice-versa) and partially or completely

modify the message(s) being sent from Bob to Alice. For example, she can easily

change the phrase “Alice, I owe you $1000” to “Alice, I owe you $10,000”.

Furthermore, Trudy can even drop the packets that are being sent by Bob to Alice

(and vise-versa), even if the packets from Bob to Alice are encrypted.

Chapter 1 Problems:

Problem 1.

There is no single right answer to this question. Many protocols would do the trick.

Here's a simple answer below:

Messages from ATM machine to Server

Msg name purpose

-------- -------

HELO <userid> Let server know that there is a card in the

ATM machine

ATM card transmits user ID to Server

PASSWD <passwd> User enters PIN, which is sent to server

BALANCE User requests balance

WITHDRAWL <amount> User asks to withdraw money

BYE user all done

剩余63页未读，继续阅读

评论收藏

内容反馈

rrryyyhhhddd

2013-10-19

可以用来参考，确实是中文版的答案
chaizhanhui

2013-05-12

这是中文书的答案，和英文的有些出入。不过可以拿来参考一下。

freepuw

粉丝: 0
资源: 1

计算机网络自顶向下方法 第四版 英文版答案

计算机网络自顶向下方法第四版答案(英文版)

计算机网络自顶向下方法第四版英文版答案

计算机网络(自顶向下方法)第四版答案英文版

计算机网络自顶向下方法第四版答案

计算机网络自顶向下方法第四版答案（英文版）

《计算机网络自顶向下（第七版）》课后题最全答案-含题目

计算机网络自顶向下方法_课后习题答案（英文第四版）

计算机网络 自顶向下 习题答案 中文+英文版

计算机网络自顶向下方法第五版英文

计算机网络自顶向下方法第四版中英文答案

计算机网络自顶向下方法第四版原书英文答案

计算机网络自顶向下方法答案(英文第六版)

计算机网络：自顶向下方法 英文答案 第四版

计算机网络自顶向下方法第四版答案(英文)

计算机网络自顶向下第六版第四版综合答案.zip

计算机网络-自顶向下方法(第五版)英文版课后题详解

计算机网络自顶向下方法(英文版)第四版答案

计算机网络自顶向下方法第四版答案,英文的

计算机网络(自顶向下方法)第四版答案(英文版)

计算机网络 自顶向下 英文版 第四版 课后题答案

计算机网络自顶向下第三版中文答案/第四版英文答案

北邮大三上2022年《算法设计与分析》期末试题-A卷

计算机毕业设计答辩PPT模板（11套）.zip

2019city.zip

1000套计算机毕业设计带源码

【浏览器插件】Zotero Connector.zip

最新资源

计算机网络自顶向下方法第四版英文版答案

计算机网络自顶向下习题答案中文+英文版

计算机网络：自顶向下方法英文答案第四版

计算机网络自顶向下英文版第四版课后题答案