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000101_news@columbia.edu _Thu Jan 20 12:26:35 2000.msg
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Message-ID: <3887C038.9B555184@willow.iie.pz.zgora.pl>
From: Michal <mpolak@willow.iie.pz.zgora.pl>
Organization: Technical University of Zielona Gora
Subject: MNP
Date: Thu, 20 Jan 2000 17:12:51 GMT
To: kermit.misc@columbia.edu
Hi,
I have been trying to establish an MNP connection for some days ago, but
unfortunately I did not succeed. However, I have not given up yet. In
this email I'd like to share with you all these problems I faced.
First of all, I cannot find any documentation which describes how to
perform MNP training, starting from the phase of exchanging ODPs/ADPs,
and finishing when the first link-request PDU should be transmitted by
the originating modem. As there is said in the ITU V.42 recommendation
the originator should start sending the ODPs and examine incoming bit
stream from the answering modem. The ODP for LAP-M is defined as "EC"
and "E(Null)"when no error-correcting protocol is desired.
If no ADPs have been received within 750 ms (default) the calling modem
can check whether there is a presence of an alternative error-correcting
protocol, in this case - MNP. At this point I get confused. This is not
clear for me if a remote end supporting MNP sends any ADPs, or there is
another way to detect the presence of this protocol. Anyway, I could
check that some remote modems send "EM" (after converting to the
synchronous form) if MNP has been chosen on these modems. Obviously I am
not sure if these letters mean that the answering modem is capable of
supporting MNP, since I do not have any paper saying so. I would be very
appreciate if you could explain to me how the "MNP" ADP is defined, and
where I can find some information on it.
My second question is quite simple, I think. Namely, as you know, when a
LAP-M connection has been established, and no data is being sent, the
start/stop flags should be transmitted (0x7e). What in case of MNP? I
guess that when bit-oriented mode (synchronous) has been selected,
0x7e's are to be transmitted as well. But what if octet-oriented mode
(asynchronous) has been chosen? I could not find any notes on this
anywhere, anyway I suppose that empty frames shall be transmitted.
Another problem is the structure of these frames - do not know where to
find any description.
Additionally, I'd like to make sure that the default framing mode is the
octet-oriented one (used when sending the first LR PDU, and it is valid
at least till the protocol establishment phase is completed; it can be
changed during the protocol negotiation phase).
Could you please answer and make comments to these questions above?
I am looking forward to receiving your answers soon.
Please reply to my email address as well
(mailto:mpolak@willow.iie.pz.zgora.pl)
Best regards,
Michal