The following options control the appearance of various features in Time Sequence Graphs 5.1.
An ack is plotted with a RED diamond head if the ack is ambiguous due to the fact that the segment being acknowledged was retransmitted. This is illustrated in Figure 7.1.
Notice that the ack packet that causes the green line to go up towards the right-hand end of the graph has a RED diamond nailed on it. As can be seen in the graph, the segment that is being acknowledged by the ack packet had been retransmitted.
An ack packet is plotted with a BLUE diamond head if the ack is ambiguous due to the fact that one of the segments being cumulatively acknowledged by it was retransmitted. This is illustrated in Figure 7.2.
If you look closely at towards the right end of the Figure, you may notice that the green line has a blue diamond head on the top. This is due to the fact that a segment being cumulatively acknowledged by this ack had been retransmitted.