Certainly, let's delve into the details of multiplexing, demultiplexing, and the role of ports in the transport layer:

Multiplexing and Demultiplexing:

• Multiplexing in the transport layer refers to the capability of sending multiple data streams from different applications over a single network connection.
• Demultiplexing is the process of correctly delivering incoming data packets to their respective applications on the receiving end.

Ports and Socket Addresses:

• Ports are 16-bit numbers used to differentiate between different services or applications on a networked computer.
• They allow multiple services to run on a single device without interference.
• When combined with an IP address, a port forms a socket address or socket number.
• Socket addresses help direct data to the correct service on a device. For example, "10.1.1.100:80" refers to the IP address 10.1.1.100 and port 80.

Server and Client Concept:

• In the client-server model, servers are programs or services waiting to fulfill client requests.
• Clients request data or services from servers by sending messages.
• Different services (e.g., web, email, file transfer) run on specific ports to listen for incoming client requests.

Examples of Port Usage:

• HTTP, the protocol for web traffic, traditionally runs on port 80. So, "10.1.1.100:80" directs traffic to a web server.
• FTP, used for file transfers, listens on port 21. "10.1.1.100:21" points to an FTP server.

Port Range:

• Ports are numbered from 0 to 65535.