Re: Dialup networking/ppp

[Ignatios Souvatzis <is%netbsd.org@localhost>]

On Wed, Sep 12, 2001 at 11:33:29PM +0100, Lars Hecking wrote:
> 
> 
>  Not a snowball's chance in hell that I could get hold of such a device :-/
> 

Oh... every other PC dealer, and every electronic dealer here, has them.
I consider them, together with a simple multimeter (to check broken wires, 
voltages, and hung
interupts on Level-Interupt systems like M68K), to be basic debugging
tools. :-)

> > Amiga_. Then you should do the same _right at the modem_, however here you
> > can look at the modem LEDs in most cases.
> > 
> > In both cases, when you do a bulk FTP upload, CTS should go 
> > off sometimes, and _at the same times_ TxD should be quiet; similarly,
> > if you do an FTP download, RTS shoudl go off sometimes, and RxD should
> > be quiet at the same time.
>  
>  I'm too lazy to look up what CTS and RTS mean, but in case of downloads,

clear to send, request to send, where the RTS line is rather used as
"clear to receive". That is

- The modem switches CTS off to tell the computer "don't send more bytes at 
  the moment"

- The computer switches RTS off to tell the modem "don't send more bytes at
  the moment"

If one of them doesn't generate them, or the other doesn't obey, or the cable
(or connectors) in between doesn't transmit them, you'll lose data eventually.
Losing a byte is losing a whole IP packet, and then TCP waits for retransmit.

You write that it started when the 060 went it. Is it the 060 per se, or did
you switch to the cbiiisc device (the cs Mk 3 onboard ScSI) at the same time?

A couple of other (P5 scsi controller) drivers limit the DMA length in case
of high speed builtin-serial bit rate, because P5 seems to not leave CPU
access cycles in between a DMA run. Maybe the cbiii has the same problem,
or the big cpu cache (creating long uninteruptible "flush cache" instructions)
bytes you.

You didn't mention your serial speed setting. Try to make it small, say
19200 bps, and see if you get better througput. THis will give us a hint as to
what to look for.

Regards,
        -is