Computer networking a top down approach 6th edition solutions năm 2024

Solution Manual for ComputerNetworking: A Top-Down Approach, 6/E6th Edition

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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 Let server know that there is a card in the ATM machine ATM card transmits user ID to Server PASSWD User enters PIN, which is sent to server BALANCE User requests balance WITHDRAWL User asks to withdraw money BYE user all done

Messages from Server to ATM machine (display)

Msg name purpose -- - PASSWD Ask user for PIN (password) OK last requested operation (PASSWD, WITHDRAWL) OK ERR last requested operation (PASSWD, WITHDRAWL) in ERROR AMOUNT sent in response to BALANCE request BYE user done, display welcome screen at ATM

Correct operation:

client server HELO (userid) --> (check if valid userid) <- PASSWD PASSWD --> (check password) <- OK (password is OK) BALANCE -->

<- AMOUNT WITHDRAWL --> check if enough $ to cover withdrawl <- OK ATM dispenses $ BYE --> <- BYE

In situation when there's not enough money:

HELO (userid) --> (check if valid userid) <- PASSWD PASSWD --> (check password) <- OK (password is OK) BALANCE --> <- AMOUNT WITHDRAWL --> check if enough $ to cover withdrawl <- ERR (not enough funds) error msg displayed no $ given out BYE --> <- BYE

Problem 2

At time N*(L/R) the first packet has reached the destination, the second packet is stored in the last router, the third packet is stored in the next-to-last router, etc. At time N*(L/R) + L/R, the second packet has reached the destination, the third packet is stored in the last router, etc. Continuing with this logic, we see that at time N*(L/R) + (P-1)*(L/R) = (N+P-1)*(L/R) all packets have reached the destination.

Problem 3

1. A circuit-switched network would be well suited to the application, because the application involves long sessions with predictable smooth bandwidth requirements. Since the transmission rate is known and not bursty, bandwidth can be reserved for each application session without significant waste. In addition, the