[comp.os.vms] Async DECnet with error-correcting modems

Larry_J_Osterman@cup.portal.com (10/25/87)

Does anyone know of a 9600 baud asynchronous dialup modem usable
with VMS asynchronous dynamic DECnet?

We are trying to use a pair of FASTCOMM 9600 modems to do this.
We can make a connection to the remote machine by doing a SET
HOST/DTE, and dialing using the Hayes-compatible dialing
commands.  We then login without a problem, but when we do the
SET TERM /SWITCH=DECNET /PROTOCOL=DDCMP, the DECnet link refuses
to come up.  There are no error messages, indicating we've
properly got dynswitch installed, virtual terminal support
enabled, terminals set to disconnect, etc.  NCP says there are no
verification errors, meaning our passwords are set up OK.
However, SHOW LINE COUNTERS shows "initialization" errors.  The
number of these errors increases as time goes by.

The FASTCOMM uses a CRC-based error correction scheme at its 4800,
7200, and 9600 baud speeds.  The scheme is called "Ensured Data
Integrity", and is compatible with some CCITT X.* recommendation.

DEC's Colorado CSC points out that the DECnet-VAX 4.4 SPD states
that asynchronous DECnet is not supported when there is a data
switch, terminal server, etc. in the connection.  Though error-
correcting modems are not mentioned, the support person said that
DECnet developers have encountered problems using them.  The
support person also said that he has fielded a number of calls
from users who were having trouble establishing asynchronous
DECnet connections through multiplexors.

Can anybody shed any light on this?

Larry Osterman
GTE Telecom, Incorporated
Suite 1717
One Tampa City Center
Tampa, Florida 33607
(813) 222-5713