RFC 864 (rfc864) - Page 1 of 3

Character Generator Protocol

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Network Working Group                                          J. Postel
Request for Comments: 864                                            ISI
                                                                May 1983



                      Character Generator Protocol




This RFC specifies a standard for the ARPA Internet community.  Hosts on
the ARPA Internet that choose to implement a Character Generator
Protocol are expected to adopt and implement this standard.

A useful debugging and measurement tool is a character generator
service.  A character generator service simply sends data without regard
to the input.

TCP Based Character Generator Service

   One character generator service is defined as a connection based
   application on TCP.  A server listens for TCP connections on TCP port
   19.  Once a connection is established a stream of data is sent out
   the connection (and any data received is thrown away).  This
   continues until the calling user terminates the connection.

   It is fairly likely that users of this service will abruptly decide
   that they have had enough and abort the TCP connection, instead of
   carefully closing it.  The service should be prepared for either the
   carfull close or the rude abort.

   The data flow over the connection is limited by the normal TCP flow
   control mechanisms, so there is no concern about the service sending
   data faster than the user can process it.

UDP Based Character Generator Service

   Another character generator service is defined as a datagram based
   application on UDP.  A server listens for UDP datagrams on UDP port
   19.  When a datagram is received, an answering datagram is sent
   containing a random number (between 0 and 512) of characters (the
   data in the received datagram is ignored).

   There is no history or state information associated with the UDP
   version of this service, so there is no continuity of data from one
   answering datagram to another.

   The service only send one datagram in response to each received
   datagram, so there is no concern about the service sending data
   faster than the user can process it.



Postel
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