+Client computer: IP address: 192.168.0.117, TCP port number: 49401 +Destination computer: attach.mai.vip.gq1.yahoo.com IP address 67.195.13.132: TCP port number: 80 Figure1: IP address and TCP port numbers of the client computer and destination computer +The sequence number is 0x0050c6d0(5293776 in decimal, relative value of 0). The segment is identified as a SYN segment because the SYN flag set is 1 (or in the flag byte ( 0x02 = b00000010)is set). Figure2: Sequence number of the TCP SYN segment + The sequence number is 0x31a389b7 (832801207 in decimal, relative value =0). The ACK number is 0xc6e0edaa (3336629674 in decimal, relative value =1). The server determined this number by adding 1 to the sequence number sent in the previous segment by the client. This segment is identified as a SYNACK segment because both the SYN and ACK flags in the flag byte (0x12 = b00010010) is set. +the sequence number of the TCP segment containing the HTTP POST command is: 0xc6e0edaa Figure3: Sequence number and Acknowledgement number of the SYNACK segment +The HTTP POST segment is considered as the first segment. Segments are No. 4, 5, 6 in this trace respectively. The ACKs of segments are No.8, 9, 14 in this trace. (Figure 1) The sequence number, sending time and the received time of ACKs are tabulated in the following table. Sequence number Sent time ACK received time RTT (second) Segment 1 1 0.322606 0.685634 0.363028 Segment 2 815 0.322860 0.698228 0.375368 Segment 3 1295 0.323210 1.338814 1.015604 EstimatedRTT = 0.875 * EstimatedRTT + 0.125 * SampleRTT EstimatedRTT after the receipt of the ACK of segment 1: EstimatedRTT = RTT for Segment 1 = 0.363028 second EstimatedRTT after the receipt of the ACK of segment 2: EstimatedRTT = 0.875 * 0.363028 + 0.125 * 0.375368 = 0.326407 EstimatedRTT after the receipt of the ACK of segment 3: EstimatedRTT = 0.875 * 0.326407 + 0.125 * 1.015604 = 0.41256 + Length of the first TCP segment (containing the HTTP POST): bytes +Length of each of other TCP segment: bytes (MSS) +The minimum amount of buffer space (receiver window) advertised at yahoomail.com for the entire trace is 65535 bytes, which shows in the first acknowledgement from the server. This receiver window grows steadily until a maximum receiver buffer size of 62780 bytes. The sender is never throttled due to lacking of receiver buffer space by inspecting this trace. Minimum receive window advertised at destination computer . address: 192.168.0.117, TCP port number: 49401 +Destination computer: attach.mai.vip.gq1.yahoo.com IP address 67.195.13.132: TCP port number: 80 Figure1: IP address and TCP port numbers of the. 0.326407 + 0.125 * 1.015604 = 0.41256 + Length of the first TCP segment (containing the HTTP POST): bytes +Length of each of other TCP segment: bytes (MSS) +The minimum amount of buffer space. both the SYN and ACK flags in the flag byte (0x12 = b00010010) is set. +the sequence number of the TCP segment containing the HTTP POST command is: 0xc6e0edaa Figure3: Sequence number and Acknowledgement