Question

An engineer decides to set the initial congestion window size to 100 segments. Is this a good idea?An engineer decides to set the initial congestion window size to 100 segments. Is this a good idea?

Answer 1

yes, it is good idea.

Sender window = minimum ( Congestion window, Receiver window)

• If RW > CW, then sender window = CW and congestion control policy will be used. It indicates that receiver can accept more data but intermediate routers cannot.
• If RW < CW, then sender window = RW and flow control policy will be used. So no need to set any threshold here.

GIven, CW = 100 MSS and let take RW = 16 MSS

so, sender window = 16 MSS. No congestion here. We can either use stop-n-wait or selective repeat flow control policy.

Using stop and wait (we send 1 MSS in 1 RTT) = 16*1 ms = 16 ms

Using selective repeat (entire window is sent during one RTT) = 1 ms.

It is not a slow start process, in slow start process congestion increases as process goes on..so, this is good idea.

In this, we dont need to set any threshold value which we can get by the formula, initial threshold value = current congestion window size / 2.

so this is good idea.