TCP flow control:
https://www.bilibili.com/video/BV19E411D78Q?p=66
Flow control: Let the sender to slow down , let the recipient had time to receive.
Using the TCP sliding window mechanism to achieve flow control.
During communication, the receiving side according to their receive buffer size , dynamically adjust the transmission window size of the transmitter, i.e. the receiving window rwnd (recipient setting acknowledgment packet segment window field to the rwnd notification to the sender), the sender the transmission window for the minimum reception window and the congestion window cwnd is rwnd.
Host B hands three times:
1, said window inflicted, 300; 2, said window inflicted 100; 3, said window inflicted 0
In order to avoid the blind to wait :
For each TCP connection has a - a continuous timer, as long as the other party TCP connection to receive notice of zero window, the timer will start continued.
If the duration of the timer is set to expire, it will send a zero-window probe segment . The window will now be given upon receipt of the detection value of the receiver segment.
If the window is still 0, then the sender would reset the timer duration.
TCP congestion control:
https://www.bilibili.com/video/BV19E411D78Q?p=67
Congestion conditions occur:
> the total available resources for the resource requirements of
the network has many resources while exhibiting insufficient supply network >> >> network throughput performance will deteriorate with increasing input load decreases
congestion control:
to prevent excessive data injection to the network. Overall
Congestion Control & Flow Control:
Congestion control four algorithms: [PubMed does not examine the details]
slow start
congestion avoidance
fast retransmission
and fast recovery
Assumed:
1. Data transmission in one direction and the other direction by transmitting an acknowledgment
2. The receiver always has a sufficiently large buffer space, and thus the transmission window size depends on the congestion degree of
the send window = Min {receiving window rwnd , the congestion window CWnd }
receive window: the receiver receiving side in accordance with the capacity to accept the cache setting value, and informs the sender reflected.
Congestion window: the sender window value according to the degree of network congestion own estimates provided reflect the current network capacity.
