> -----Original Message-----
> From: Richard Morrell [mailto:portmaster@ednet.co.uk]
> Sent: Thursday, March 25, 1999 05:29
> To: James Courtier-Dutton
> Cc: Patrick Kormann; portmaster-users@livingston.com
> Subject: RE: (PM) pm3 disconnects
>
>
> > ISDN PPP gives better performance than V.120, this is because
> V.120 adds a
> > lot of overhead because V.120 is Async, and ISDN is sync.
> > Doing Async over a sync line is not an easy task. You basically
> have to send
> > a whole sync frame for each async character.
>
> That's correct, but I find the async penalty under V.120 to be approx
> 12.5% rather than the 50%-60% Patrick is seeing.
That is probably because the TA is trying to do V.120 error correction, and
the PM3 does not do that. (Who needs error correction on a digital ISDN
link). Most sensible TAs default to error correction off, but you have a few
brain dead ones. Some S register normally can be used to switch it off. (At
least PAXDATA TA required this to work according to a PAXDATA engineer.)
It is easier to switch the TA to PPP mode, instead of searching for V.120 S
registers, so I would just switch it to PPP.
>
> --
> Richard Morrell
> richard@ednet.co.uk
> System Administrator - edNET: Internet Access for Edinburgh -
> www.ednet.co.uk
>
>
>
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