Question 44

Since the slow-start threshold is $10000 > 2000$ and no loss occurs, TCP remains in slow start throughout, doubling its congestion window every $\text{RTT} = 1\text{ ms}$:

• At $t = 0\text{ ms}$ ($\text{cwnd} = 1$): sends segment $1$.
• At $t = 1\text{ ms}$ ($\text{cwnd} = 2$): sends segments $2$ to $3$.
• At $t = 2\text{ ms}$ ($\text{cwnd} = 4$): sends segments $4$ to $7$.
• In general, in the round starting at $t = k\text{ ms}$ ($\text{cwnd} = 2^k$), the sender transmits segments $2^k$ through $2^{k+1} - 1$.

For $k = 10$ ($t = 10\text{ ms}$), the sender transmits segments $2^{10} = 1024$ through $2^{11} - 1 = 2047$. Since $1024 \le 2000 \le 2047$, segment $2000$ is transmitted during the interval $10 \le t < 11$.