Hello Deepak

The segment size will not change over the course of the transmission. For most transmission media, TCP segment sizes are usually (but not always!) around 1500 bytes. This lesson and its example deals only with the change in size of the window. It is the window size that grows exponentially (when using slow start). So in the example I gave, the next window size should be 14000 bytes. This means that we would have the following set of segments sent:

Segment 1: SEQa = 7001, Window Size = 14000, , segment size = 1500 Bytes

Segment 2: SEQa = 8501, Window Size = 14000, , size = 1500 Bytes

Segment 3: SEQa = 10001, Window Size = 14000, , size = 1500 Bytes

Segment 4: SEQa = 11501, Window Size = 14000, , size = 1500 Bytes

Segment 5: SEQa = 13001, Window Size = 14000, , size = 1500 Bytes

Segment 6: SEQa = 14501, Window Size = 14000, , size = 1500 Bytes

Segment 7: SEQa = 16001, Window Size = 14000, , size = 1500 Bytes

Segment 8: SEQa = 17501, Window Size = 14000, , size = 1500 Bytes

Segment 9: SEQa = 19001, Window Size = 14000, , size = 1500 Bytes

Segment 10: SEQa = 20501, Window Size = 14000, , size = 1500 Bytes

Segment 11: SEQa = 21001, Window Size = 14000, , size = 500 Bytes

So the window size doubles, the segment size remains the same (except for the last one which is 500 bytes) and now 11 segments are sent within that window. The window will double again after every successful acknowledgement of the receiver until some data is dropped. If this happens, the window size goes down to one segment again, that is 1500 bytes. It will grow exponentially again until the window is at half of what it was when the original congestion occurred. Window sizes will then grow linearly.

I hope that has been helpful!

Laz