Q. In transport layer, Multiplexing is done at

Explanation by: Mr. Dubey

 at the sender’s side, there are multiple processes which may want to send packets. but there is only one transport layer protocol like tcp or udp working at a time. so the transport layer protocol gets the messages from these processes and separates them with different port numbers. this process is called multiplexing and it is done before sending packets to the receivers side.