TCP packet loss (congestion, timeout) retransmission occurs

Detailed analysis can be performed based on the SEQ sequence number and ACK sequence number of the Wireshark.

Visible, the network drops (may be network congestion, it is possible that the backbone of the "firewall" intentionally randomly dropped packets, because the server's IP in foreign countries) for the network response will have a great impact.

Retransmission after a packet loss (or timeout) is an important mechanism in the TCP protocol. This mechanism can have different strategies. Worthy of study and careful analysis.

In the I will not unfold.

Only describes the retransmission that occur in TCP applications. All this if not by grasping the package, the user is not aware of, may feel the "network slow."

UDP does not occur, even if retransmission, is the application layer to decide retransmission.

TCP packet loss (congestion, timeout) retransmission occurs