Delayed ACK 和 nagle算法

Nagle算法作用为延迟发送，其意为，不足MSS的数据直到收到确认再发送

Nagle’s Algorithm：(RFC 896)

 if there is new data to send
      if the window size >= MSS and available data is >= MSS
        send complete MSS segment now
      else
        if there is unconfirmed data still in the pipe
          enqueue data in the buffer until an acknowledge is received
        else
          send data immediately
        end if
      end if
    end if

    
延迟确认为减少通道中包的数目，如果应答方有数据传输，或有两个ACK需要发送，则发送数据包，否则等待，直到timer超时

Delayed ACK: (RFC1122)

    while(timer<ack_delayed_timer)
    {
        if(there_is_a_segment_from_source())
            segment_received++; 
        
        if(segment_received==1 && is_possible_piggy_back())
        {
            piggy_back(sequence_number_of_the_last_segment+1); # ACK within the data
            segment_received=0;
            timer=0;
            break;
        }

        # if 2 consecutive segments are received, we send a pure ACK
        if(segment_received==2)
        {
            send_pure_ack(sequence_number_of_the_last_segment+1);
            segment_received=0;
            timer=0;
            break;
        }
    }