>The modems are very similar -- both are TrailBlazer modems.  They don't
>seem to have any problems communicating without PPP (I am composing this
>over the modems).

>Michael
>michael@osg.saic.com

I can't tell you much about PPP negotiation but I can try to help you make 
sure your modems are configured properly.

1) Are you using a Telebit TrailBlazer or TrailBlazer Plus, model etc.?

2) Your connection sounds good, but odds are, you have data compression and 
error correction turned on.  Under data streaming conditions, these modes 
are good but under SLIP and PPP they cause more trouble than it is worth. 
 The problems is, your are putting packets inside of packets not to mention 
you are placing compressed error correcting packets inside compressed error 
correcting packets(assuming this option is turned on), very redundant.

This all results in unaligned packets and unnecessary over head.  In 
personal tests, I saw a 5-10% decrease in performance from a FTP xfer when 
the modem's error correction and data compression was turned on over when it 
was turned off.  Not to mention negotiations seem to take longer (in your 
case, timing may be more critical that mine).  Another possibility may be 
that your modems may me attempting to connect via PEP, Telebit's own 
propriety error correcting protocol, so your timings are going to be very 
different from mine and others just using V.42 or MNP 4 and V.42bis.

3) Try turning compression and error correction off.
S95=0 MNP error correction disabled
S96=0 MNP data compression disabled
S97=0 V.42 disabled (error correction)
S98=0 V.42bis disabled (data compression)
S106=0 disable V.42 detection
There is one other register that needs to be set to either S66=0 or 1, I'm 
not sure which one (try 1 first).

If this helps great, at least you should improve performance when you do get 
it fixed.

enjoy,
jam

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*       John A. Maier          * Research Assistant For Datastorm    *
* E-mail: johnam@datastorm.com * Technologies Inc. (Procomm Plus)    *
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