JUST LOOK THE BELOW EXAMPLE -->
let adv. window(receiver capacity)=16KB
mss=1KB
max window size (packet we send in one window) = 16 segment ( 16 KB / 1 KB =16 )
now reciever at the position to hold all the 16 segments even we send all at once ,but congestion control says that dont send all 16 segments once because network is not able to position to hold that.
threshold=( max packet we send in one window ) / 2 = (16 segment ) /2 =8 segment
first we send 1 packet then increase exponentially till threshold , then linearly till max which is 16segment here , and then constant
so order we send segment is - (1 2 4 8 9 10 11 12 13 14 15 16 16)
so it increases exponentially after every RTT till threshold which is called slow start phase (name is slow but process is not slow)
after threshold - congestion avoidance phase starts ( here growth is linearly)