盘算机网络:自顶向下 第一章 课后习题参考答案(官方文档中文解析)

清酒暖风

媒介

关于常识面的把握不克不及仅仅是晓得，可以减以使用才气纯熟把握，计较机收集：自顶背下那本书中为读者供给了契合的习题去协助我们操练。接下去我将战各人一同解读民圆谜底文档（英文），并给出我所了解的中文翻译(英语好的读者倡议间接寓目民圆英语文档，部门标题问题笔者才能有限没法解问)。
Chapter 1 Problems

Problem 1

英文：

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 namepurposeHELO Let server know that there is a card in the ATM machine and ATM card transmits user ID to ServerPASSWD User enters PIN, which is sent to serverBALANCEUser requests balanceWITHDRAWL User asks to withdraw moneyBYEuser all doneMessages from Server to ATM machine (display)

Msg namepurposePASSWDAsk user for PIN (password)OKlast requested operation (PASSWD, WITHDRAWL)ERRlast requested operation (PASSWD, WITHDRAWL) in ERRORAMOUNT sent in response to BALANCE requestBYEuser done, display welcome screen at ATMCorrect operation:

[table][tr]clientserver[/tr][tr][td]HELO (userid)[/td][td]--------------> (check if valid userid)[/td][/tr][tr][td][/td][td] (check password)[/td][/tr][tr][td][/td][td][/td][td][/td][/tr][tr][td][/td][td] check if enough $ to cover withdrawl[/td][/tr][tr][td][/td][td][/td][td][/td][/tr][tr][td][/td][td] (check if valid userid)[/td][/tr][tr][td][/td][td] (check password)[/td][/tr][tr][td]BALANCE -------------->[/td][td][/td][/tr][tr][td][/td][td][/td][td][/td][/tr][tr][td][/td][td] (查抄是用户可合理)[/td][/tr][tr][td]（请输进密码）[/td][td] (查抄密码)[/td][/tr][tr][td]密码准确[/td][td][/td][td]（恳求存款）[/td][/tr][tr][td]（输进存款金额）[/td][td] （查抄余额能否充足）[/td][/tr][tr][td]（账户余额充足）[/td][td][/td][td]（效劳结束）[/td][/tr][tr][td]（效劳结束）[/td][td] (查抄是用户可合理)[/td][/tr][tr][td]请输进密码[/td][td] (查抄密码)[/td][/tr][tr][td]密码准确[/td][td][/td][td]（恳求存款）[/td][/tr][tr][td]（输进存款金额）[/td][td] （查抄余额能否充足）[/td][/tr][tr][td][/td][td]（无款项收入）[/td][/tr][tr][td]BYE -------------->[/td][td]效劳结束[/td][/tr][tr][td]效劳结束[/td][td]