In LANs based on the TCP/IP standard, the 2-byte port number is used to uniquely address a specific application within a computer. Only the combination of port number (socket) and processor number (IP address) uniquely identifies the sender or receiver of a message within a network.
0 | 1024 | 65535 |
“Well-known” port numbers | Dynamically allocated | |
Division of port numbers in accordance with TCP/IP
Addressing socket applications
Socket applications are addressed by means of their port numbers. The port numbers lie within the value range of 0 to 65535 and are split into three areas. The default BCAM values listed in the following table can be modified using a command (see FREEPORT# and PRIVPORT# in the commands BCMOD, DCOPT, and DCSTART). Port numbers for userown applications should be placed in the area between PRIVPORT# and FREEPORT#.
0 | PRIVPORT# | FREEPORT# | 65535 | |||
Fixed port numbers for privileged applications (services) | Fixed port numbers for nonprivileged applications(services) | Dynamically allocated port numbers | ||||
Default distribution of port numbers in BCAM