Reverse telnet is a specialized application of telnet, where the server side of the connection reads and writes data to a computer terminal line (RS-232 serial port), rather than providing a command shell to the host device.
Typically, reverse telnet is implemented on an embedded device (e.g. terminal/console server), which has an Ethernet network interface and serial port(s).
In the past, reverse telnet was typically used to connect to modems or other external asynchronous devices.
Today, reverse telnet is used mostly for connecting to the console port of a router, a switch or other device.
In this example, 172.16.1.254 is the IP address of the console device, and 2002 is the TCP port associated with a terminal line on the server.