[ns] TCP ???

[Arijit Ganguly <arijitg@tct.hut.fi>]

Hello seniors

Please let me know which one of the following two strategies is
implemented in ns2 TCPReno.

A TCP receiver(TCPSink), this accepts a packet only when its
sequence number is equal to the one which it is expecting, discarding
all other packets. (go back n). This way all packets sent following a
loss will trigger duplicate acks.

Or the TCPSink agent, has some buffering to accept packets which fall
within in receiving window(may be not the same as what it is expecting).
This way a gap in the sequence number can filled up later, without having
to retransmit all packets again.

I would also like to know which one of the strategies is implemented in
TCP/IP stack of modern operating systems.

Please reply
Arijit