tcp/ip header revisited....
client				server
send syn w/ seq num = x
				send syn+ack (both in flags) with seq num=y and ack = x+1
send ack w/ ack num = y+1

flow control - receiver controls how fast sender pumps tcp packets into connection
congestion control - network throttles sender because the network is at capacity
no min BW guarantees

UDP...fun
page 382
we'll be using tcpdump (windump) and wireshark
they use pcap

internet header length (min val is 5, mult by 4 to get bytes)
going over wireshark....
api!
socket - a "door" between app process and end to end xport protocol
socket handout has c code for socket usage