Question

Nagle algorithm

Suppose a transmitter application wants to send the letters "abcdefghi", one letter per second. The transmitter uses a TCP connection with an RTT of 4.3 seconds. Assuming the use of Nagle's algorithm, show, using a table, the time of sending and the contents of each packet sent.

Answer 1

Nagle's Algorithm:-

1. Sender will send first byte immedeatly produced by the application.
2. Then sender will buffer all the remaining produced bytes untill last sended packet gets acknowledged, That is sender will wait for 1 RTT for every packet transmission after 1st packet.

Data produced by the Application:- 'abcdefghi'

Data production rate:- 1 character/second

We will consider timer starts from 0 for reference. And I'll assume all delays are '0'.

Table:-

Packet number	Data	Transmission time (t)
0	"a"	1
1	"bcde"	5.3
2	"fghi"	9.6

Packet number '0' will containf only 1st produced letter which is "a" and will transmit at "t" = 1 second.

After this, sender will wait for 4.3 seconds for recieving acknowledgement of 1st packet during this packet sender's application will produce 4 more letters "bcde". So after acknowledgement of 1st packet at "t" = 5.3 second, sender will send these 4 letters in packet '1'.

After this, sender will again wait for 4.3 seconds for recieving acknowledgement of 2nd packet during this time, sender's application will produce 4 more letters "fghi". So after acknowledgement of 2nd packet at "t" = 9.6 second, sender will send these 4 letters in packet '2'.