Consider a $\text{TCP}$ flow sending three segments, namely $1,2,$ and $3.$ Due to congestion, the $\text{TCP}$ flow experiences exactly two losses. Only segments can be lost; acknowledgments are not lost.
Segments $1$ and $3$ are lost in their first transmission. $\text{TCP}$ detects packet loss either through timeout or three duplicate $\text{ACKs}.$ Let the initial congestion window size be $1,$ and the receiver sends an acknowledgment for each packet upon successful receipt.
The transmission time of a segment is negligible, and the round-trip time is $\text{RTT}.$ The re-transmission timeout $(\text{RTO})$ is twice the $\text{RTT},$ i.e., $\text{RTO} = 2 \ast \text{RTT}.$
How much time $\text{(in RTT)}$ will it take for the $\text{TCP}$ sender to receive acknowledgments for all packets successfully?
- $\text{3 RTTs}$
- $\text{5 RTTs}$
- $\text{6 RTTs}$
- $\text{8 RTTs}$
