(PMOD) Known PM3 modem issues.

Bud Bennett (bennetb@cadvision.com)
Thu, 17 Jun 1999 09:23:58 -0600

Rather than complaining about faulty modem code, I think the more productive
thing to do is directly address client modem issues and find out just where
all the problems lie. Unfortunately, I can't give detailed information at this
time but I think this is a start. I do realize that a PM3 can't be everything
to everyone, I think the problem is more along the lines of producing modem
code that is more accommodating to modems that are outside of V.90 spec.

On a side note, Some of our techs say that the PM3's are "Too Aggressive" in
determining connect speed, (IE. Letting a client modem connect too fast for
the line conditions.) so they have to manually kick down the top speeds for
stable connects. This seems to be a reoccurring thing. Is there a way for the
modem code engineers to make the server side modems behave more conservatively
when it comes to initial speed handshaking?

All of our PM3A-2T's are running ComOS 3.8.2c2 ... PRI, ESF & B8ZS. I don't
plan on downgrading.

I would also like to suggest perhaps that Lucent release a white paper
(Perhaps just specific to Lucent clients?) that
explains precisely how a chassis negotiates and establishes a V.90 connection
with a client modem. What the tolerances are, what tones the server side puts
out and expects from the client modem? Perhaps if the clients can describe the
problems in better detail by using terms that are a bit more technical, they
could aid the modem engineers better.

I do honestly hope that the information below is of some use. Perhaps that
might persuade the Lucent Modem Code engineers to purchase each one of the
modems below (If they haven't already) and find out precisely where the
problems lie.

I have had a discussion with our technical support dept and here is what they
say the majority of the problems are:

Rockwell HCF V.90 code is broken. Won't handshake until you set the
client
side to use kFlex only. This is only a workaround.

USR 56k Winmodem Will not handshake properly, slow data xfer when it does
connect.

AOpen 56k's (FM56-P) Only one version of firmware, doesn't appear to help
at all.
Modem doesn't connect, same phasing problem. Will
not handshake,
rapid disconnection's (within secs of establishing a
connection) a
lot of the time, the modem will just stop responding.

Any Cirrus Logic Modem Handshake/phasing problem. Similar to the AOpens.
Will not
connect. (chipset CL-MD56xx typically)

Any ESS modem No documentation available for modem. Have a
suspected fix, but
haven't had the opportunity to test it yet. They
appear to be
bastardized USR's.

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