Question

Assume that a station X wants to send 15 packets of data to station Y using TCP Tahoe. Assuming that:

1) The size of each packet sent is 1000 Bytes (ignore all the headers from layers below).

2) Station X chooses 43 as an initial sequence number.

3) Station Y chooses 2 as an initial sequence number.

4) The data of the first packet is included in the final packet of the handshake process.

5) The sender window size is 5 packets.

6) The receiver window size is 4 packets.

7) Only the 4th packet containing data sent is lost, and the sender receives three duplicate

acknowledgments before the timeout.

8) The value of ssthresh (the threshold between slow start and congestion avoidance) is

8 packets.

9) Out of order packets are dropped.

Show the entire connection using a time diagram. Show the sequence number for each packet and acknowledgement in this communication. Identify the phases of the communication (i.e., handshake process, slow start, congestion avoidance, fast recovery, and termination of the connection).

Answer 1

=> TCP is basically a full duplex flow control mechanism in which it first establish the connection between end to end then data transfer start after data transfer , connection will be terminated.

Stepl: Data Given is Sended' x' Sequence Number =43 Sender 'y' sequence Number 2 Size of Packet 1000 Bytes Sender windan size = 5packets Receiver window size=4packets. Step2 : Connection Estabishment 1000B JUDIT seq=43, SYN=L Mss = $000 B wiscwindow)=5ccoB 10 Req backet -1OOOB-3 ③ Reply Packet Seq=2, SYN = 1 Mss = 1000B, Ws - 4000B 219 seq=44, ack=3 ACKEL BACK Packet -> mos is included in option field Cmax seg size) > TCP is FULL Duplex - Window size Capacity of Host SYN" kacket will eatup t seq number Ack=1 take 'os Seq No, - Data Byte takes t seg NO

seq=44 3 duplicates Step Data Transfer TO Der seq=3044 seq=1044 seq=2044 seg 2044 Lost seq=4044 seg 5844 489-76044 Ack-ouy Ack-2044 ACK 3044 ACK=3044 Ack=3044 ACK=17044

1 2 4-3 Duplicate 345 6 7 8 New Threshold ACK Threshold Slow Start CExponential) Linear Growth C'Congestion Avoidance) Threshold 4 -Congestion Avoidance: slow start limss