Computer Networks: A Systems Approach 5e - Exercises (1.22)

Ссылка на решение в MathCAD

Suppose that a certain communications protocol involves a per-packet overhead of 50 bytes for headers and framing.We send 1 million bytes of data using this protocol; however, one data byte is corrupted and the entire packet containing it is thus lost. Give the total number of overhead+loss bytes for packet data sizes of 1000, 10,000, and 20,000 bytes. Which size is optimal?


Оптимальный вариант - размер пакета10000 B

Computer Networks: A Systems Approach 5e - Exercises (1.4)

Ссылка на решение в MathCAD

Задачка аналогичная 1.3, но с другими условиями

Calculate the total time required to transfer a 1.5-MB file in the following cases, assuming an RTT of 80ms, a packet size of 1 KB data, and an initial 2×RTT of “handshaking” before data is sent:
(a) The bandwidth is 10 Mbps, and data packets can be sent continuously.
(b) The bandwidth is 10 Mbps, but after we finish sending each data packet we must wait one RTT before sending the next.
(c) The link allows infinitely fast transmit, but limits bandwidth such that only 20 packets can be sent per RTT.
(d) Zero transmit time as in (c), but during the first RTT we can send one packet, during the second RTT we can send two packets, during the third we can send four (23−1), etc. (A justification for such an exponential increase will be given in Chapter 6.)

Computer Networks: A Systems Approach 5e - Exercises (1.3)

Ссылка на решение в MathCAD

Calculate the total time required to transfer a 1000-KB file in the following cases, assuming an RTT of 50 ms, a packet size of 1 KB data, and an initial 2×RTT of “handshaking” before data is sent:
(a) The bandwidth is 1.5 Mbps, and data packets can be sent continuously.
(b) The bandwidth is 1.5 Mbps, but after we finish sending each data packet we must wait one RTT before sending the next.
(c) The bandwidth is “infinite,” meaning that we take transmit time to be zero, and up to 20 packets can be sent per RTT.
(d) The bandwidth is infinite, and during the first RTT we can send one packet (21−1), during the second RTT we can send two packets (22−1), during the third we can send four (23−1), and so on. (A justification for such an exponential increase will be given in Chapter 6.)

Вариант (а) - представлено решение для двух BW








Вариант (b) - представлено решение для двух BW

Вариант (c, d)

Итак, подведем краткий итог:
1. Получил сертификат курса "Computer Networks" ценой неимоверный усилий и лишений: 06.01.2014 - 18.04.2014

2. Понял что информация по Компьютерным сетям в разы объемнее того, что дается на CCNA, поэтому сижу читаю книги по Сетям и решаю задачи (раздел блога Computer Networks и Computer Networks - Exercises)