TCP and UDP Small Servers

TCP and UDP small server are services which runs on the router itself for some useful diagnostics.

TCP Small Servers

The TCP small servers are:

• Echo: Echoes back whatever you type through the telnet x.x.x.x echo command.
• Chargen: Generates a stream of ASCII data. Use the telnet x.x.x.x chargen command.
• Discard: Throws away whatever you type. Use the telnet x.x.x.x discard command.
• Daytime: Returns system date and time, if it is correct. It is correct if you run Network Time Protocol (NTP), or have set the date and time manually from the exec level. Use the telnet x.x.x.x daytime command.

Replace x.x.x.x with the IP address of your router. Most routers inside Cisco run the small servers.

UDP Small Servers

The UDP small servers are:

• Echo: Echoes the payload of the datagram you send.
• Discard: Silently pitches the datagram you send.
• Chargen: Pitches the datagram you send, and responds with a 72-character string of ASCII characters terminated with a CR+LF.