The Chicken, the Egg, and the Destination Port of the First Segment

The Chicken, the Egg, and the Destination Port of the First Segment

To allow a computer to have lots of applications that use TCP at the same time, the people who created TCP came up with the idea of a destination port number field. However, there's a small chicken-and-egg problem, and it relates to how things get started with TCP. Imagine that Keith just started his second browserthe one I called browser2 in Figure 9-11. Keith starts clicking on something to bring up browser2, and then he fills in the URL for the web page he wants to get from a web server. Figure 9-12 shows an example of the first segment sent by Keith's PC on behalf of this new browser and the response segment from the web server.