Week 4, Sept 19

Finish Sliding Windows
CRC error-check code

=================
	My example:

		A----R1----R2----R3----R4----B

		In the backward B->A direction, all connections are infinitely fast.
		In the A->B direction, the A->R1 link is infinitely fast, 
		but the other four each have a bandwidth of 1 packet/second.
		This makes the R1->R2 link the "bottleneck link" 
		(it has the minimum bandwidth, and although there's a tie for

	Case 3: SWS = 6 (for Week 4)

		window > bandwidth*delay: 
			pile up at router somewhere
			delay rises (artificially)
			bandwidth is that of bottleneck link

		example: SWS=6. Then the actual RTT rises to 6.0 sec.
		Each second, there are two packets in the queue at R1.
		avg_queue + bandwidth*no-load-RTT = 2+4 = 6 = SWS
		Now, however, *actual-RTT* is 6, and to the sender
		it *appears* that SWS = bandwidth * actual-RTT.

	sliding window:
		graphs of throughput v SWS, delay v SWS
		bandwidth x delay
		
		issues on what SWS should be
		
		flow control