Technical data

172 Agilent Connectivity Guide
7TCP/IP Network Basics
• Hypertext Transfer Protocol (HTTP)
Ports This figure shows the TCP/IP protocol stack. In the stack, TCP
and UDP each have access to 65,536 ports at the Application Layer. As
a packet moves up the stack, IP directs the packet to either a TCP port or
to a UDP port. Since all applications are listening at their respective
ports, when the packet arrives at the appropriate port, it can be
processed correctly.
Sockets For TCP/IP protocol, when a packet is delivered to a specific
IP address, it is passed up to TCP or UDP and then to the appropriate
host. This process forms a funnel through the TCP/IP stack, called a
socket. A socket is uniquely defined by the IP address, the end-to-end
protocol (TCP or UDP), and the port number.
NOTE
The Application Layer is not where an Internet browser, spreadsheet,
etc. interact. Applications running at the Application Layer interact with
the browser, spreadsheet, etc. applications.
Figure 60 TCP/IP Protocol Stack
Application Layer
Transport Layer
Internet Layer
IP
TCP
UDP
TCP/IP Stack
1
Ports
2 . . . 65,536
1 2 . . . 65,536
TCP Ports
UDP Ports