Browse Prior Art Database

Addition of Configuration Commands to V.25 Bis

IP.com Disclosure Number: IPCOM000107148D
Original Publication Date: 1992-Jan-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 4 page(s) / 142K

Publishing Venue

IBM

Related People

Petty, JS: AUTHOR

Abstract

The CCITT V.25 bis recommendation shows how a DTE (Data Terminal Equipment) can control a DCE (Data Communication Equipment) via a defined set of commands and responses. The defined commands and responses do not include any method to allow the DTE to configure the DCE. For example, using V.25 bis a DTE can make a modem dial and connect to another modem, but the DTE cannot specify the desired connection speed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 44% of the total text.

Addition of Configuration Commands to V.25 Bis

       The CCITT V.25 bis recommendation shows how a DTE (Data
Terminal Equipment) can control a DCE (Data Communication Equipment)
via a defined set of commands and responses.  The defined commands
and responses do not include any method to allow the DTE to configure
the DCE.  For example, using V.25 bis a DTE can make a modem dial and
connect to another modem, but the DTE cannot specify the desired
connection speed.

      This article shows a relatively simple modification to V.25 bis
that adds the rich configuration capabilities of the AT command set
to a V.25 bis command set.

      Basically, we implemented two general-purpose configuration
commands - one for local configuration and one for remote
configuration.  Both commands accept AT commands as parameters.

      Contrast this with the more common approach of implementing one
new V.25 bis command for each individual configurable option. One can
easily have 50 configurable options in a modern modem. The local
configuration command is named "CNL" in the 7855 V.25 bis command set
and the remote configuration command is named "CNR".  Dscriptions of
these commands based on the 7855 Guide To Operations are appended.

      The term "cmdword" means the operational portion of an AT
command.  For example, ATL0<Cr> is a complete AT command of which
"L0" is the cmdword.
CNL-Local Configuration
Format:  CNLp...px...x
Function:  This command provides a framework to enable AT cmdwords to
be sent to and run by a local modem.  For information about the
different AT cmdwords, see a copy of a switched network modem users
guide, for example, the 7855 Modem Model 10 Guide to Operation, IBM
form number GA33-0160.
Parameters:
p...p     The string of password(s) which may be required by the
local modem before the command can be run.  Some of the AT cmdwords
require either the modem's local password or the maintenance password
before they can be run.  If one of the passwords is required, it must
follow the CNL in the message field of the frame, for example
CNLb293....  If both passwords are required, the modem's local
password must come first followed immediately by the maintenance
password, for example CNLb293mmmm...  Both passwords must be four
characters long.
           A semicolon is required after the password string in
certain cases. If present, it is used to separate the password string
from the cmdword string.  If both passwords are present, the
semicolon is not required.  The semicolon is required when only one
password or no password is present, and the first cmdword in the
command string is an A, B, C, D, or E cmdword.  That is, it is
a hexadecimal character. Nothing is allowed between the L of CNL and
the first character of the local modem's password string.
x...x     A string of AT cmdwords.
Responses:  Result codes from the AT cmdwords are compacted into a
single response (like the case for...