congestion

Question

On a TCP connection, current congestion window size is Congestion Window = 4 KB. The window size advertised by the receiver is Advertise Window = 6 KB. The last byte sent by the sender is Last Byte Sent = 10240 and the last byte acknowledged by the receiver is LastByteAcked = 8192. What is the current window size at the sender ?

Answer 1

Outstanding bytes = (LastByteSent - LastByteAcked) = 10240 - 8192 = 2048 Bytes = 2KB.

Current window size = Min( Congestion Window Size, Advertised Window) = 4KB.

Now in this 4 KB window we need to have those outstanding bytes ,i.e, 2KB. So for new data remaining 2KB is used.

So answer should be 4KB.