Thursday, December 31, 2009

exercise 1 question I

Here in frame 23 the IP address 131.247.95.216 sends a packet to the IP address 64.233.161.99 using the HTTP protocol to get the fevicon.ico in http/1.1. During this process the frame 23 got some error like checksum.
The checksum provided by the IP address 131.247.95.216 is 0xc7dd but the required checksums by the destination address is 0xe685. This type error may occur due to the TCP checksum offload. According to the SEQ and ACK analysis the acknowledgment to the segment in frame 22 with the RT to ACK was 0.040800000 seconds.
Similarly the IP address 64.233.161.99 sends the reply to the IP address 131.247.95.216 through TCP protocol or by using the Http protocol. In frame 24 the segmented TCP was reassembled PDU and in the frame 25 HTTP/1.1 200 ok (image/x-icon) shows that the address is been found and send to the IP address 131.247.95.216. But in Frame 26 the IP address 131.247.95.216 sends the packet to the address 64.233.161.99 using the TCP protocol. But the checksum used in this frame is incorrect.
The checksums used in this frame is 0xc636 it suppose to be 0x9d28. This could happen due to checksum offload. The ACK/SEQ analysis provide the following information about the ACK which is been segmented in frame 25 using the ETT to ACK the segment was 0.000100000 seconds.

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