Talk:Session multiplexing

Session multiplexing is an activity in which a single computer, with a single IP address, is able to have multiple sessions occur simultaneously. A session is created when a source machine needs to send data to a destination machine. Most often, this involves a reply, but a reply is not mandatory. The session is created and controlled within the IP network application, which contains the functionality of OSI Layers 5 through 7.

A best-effort session is very simple. The session parameters are sent to UDP. A best-effort session sends data to the indicated IP address using the port numbers provided. Each transmission is a separate event, and no memory or association between transmissions is retained.

When using the reliable TCP service, a connection must first be established between the sender and the receiver before any data can be transmitted. TCP opens a connection and negotiates connection parameters with the destination. During data flow, TCP maintains reliable delivery of the data and, when complete, closes the connection.

For example, you enter a URL for Yahoo into the address line in the Internet Explorer window, and the Yahoo site corresponding to the URL appears. With the Yahoo site open, you can open the browser again in another window and type in another URL (for example, Google). You can open another browser window and type the URL for Cisco.com and it will open.

Three sites are open using only one IP connection, because the session layer is sorting the separate requests based on the port number.