z/OS Communications Server
I can’t establish a Telnet connection 


Was message EZZ6034I displayed on the console or in joblog ?   If so,  skip to the next paragraph.
If not,  we need to determine if the connection request reach this host by attempting a PING
      
Enable the TELNET DEBUG DETAIL function to receive additional diagnostic message EZZ6035I.  There will
be a Return Code within the text of the EZZ6035I message.  For a complete list of  return codes and a
description of each code,   refer to manual:

Title: z/OS V1R5 CS: IP Messages Volume 4 (EZZ-SNM)
Document Number: SC31-8786-04


Some of the more common failures are described below.   Select the hexadecimal return code from the error
message EZZ6035I:

  x’3001’  RC_LU_INUSE
  x’3002’  RC_LU_INACTIVE
  x’3003’  RC_LU_ALL_IN_USE
  x’3004’  RC_LU_NO_MATCH
  x’3012’  RC_APPL_INVLD



If you are still experiencing problems connecting to the Telnet Server,  gather the following documentation.

  Obtaining a CTRACE with the Telnet option within the TCP/IP dataspace

Or if this is a heavily used Telnet Server, the trace should be captured to an External Writer

  Obtaining a CTRACE with the Telnet option in an External Writer