On Mon, Dec 27, 1999 7:46 AM, Hauke Fath <hauke@Espresso.Rhein-Neckar.DE> 
wrote:
>At 9:35 Uhr +0100 21.12.1999, Bruce Anderson wrote:
>>A IIci should do ok.
>>For best performance disable all forms of in kernel compression.
>>( My IIci always seemed to fall behind if I asked it to do vj )

I should mention that my IIci had no cache card (slow).

>>ie: add to your options file or /etc/ppp/peers/  file
>>novj
>>nodeflate
>>nobsdcomp

This recommendation is based on my experience with three ISP's
in my area that only offer  VJ with a ppp connection.
A second reason for specifying novj is that vj conflicts with the default
setting of
rfc1323 in the kernel, so I tend to tell people to disable one.

> 
>???
>
>I cannot comment about the cost/benefit of VJ IP header compression, but
if
>your ppp peer is capable of either deflate or bsd compression, you are way
>better off when you use that and disable all modem hardware compression
>("AT %C0"). Not only is the in-kernel compression more efficient than the
>modem's, it also reduces the interrupt rate. The time-critical interrupt
>processing is much more expensive per byte than a non-time-critical data
>compression/expansion.
>
>That way, I frequently see 4 kBytes/sec when loading text web pages
through
>a 14k4 modem on a 19k2 serial line.
>
>>Your modem should have a  S register that controls
>>RTS-to-CTS delay - (my Zoom 56K uses S26=0).
>> set it to zero to reduce overflows.
>
>My modem defaults to "CTS always on".
>
>>Use the modem port rather than the printer port
>
>Not true for NetBSD. MacOS does only poll the modem port when interrupts
>are disabled (e.g. in the .Sony floppy driver).
>
>>(no fifo on the printer port).
>
>Huh? The Zilog 85c30 contains two identical ports.
>

As pointed out by Bill Studenmund <wrstuden@nas.nasa.gov> on 12/21/1999
I am in error on this point. ( Maybe I was thinking of some PPC Mac?)

>>The real disadvantage is the limited speed of the serial port.
>>(57,600bps or 5.625KB/s)
>
>I run an ISDN modem on a IIci with a port speed of 115k2 and data rates of
>up to 7200 Bytes/sec (from 8000 max.). As long as you can avoid disk
>activity and as long as you don't need any other services (DNS, Appletalk)
>from the box during data bursts, you are fine.

Yes. Avoiding retransmits and interrupts are the key elements in maximizing
throughput.

>
>>On Mon, Dec 20, 1999 9:00 AM, Jean-Francois Fortier
>><mailto:jffortier@cgocable.ca> wrote:
>>>My question is:  Will I have exactly the same result if I try it (ppp
ddr
>>>nat) on macbsd 68030 box.
>
>Again, as long as you can avoid disk acticity, an SE/30 should be able to
>keep up with 57k6 serial-to-ethernet just fine.
>
>	hauke
>





  " Stamp out root login's .  .  .  . su "
    --Bruce Anderson  Computer Programming/Networking 
      Student DCTC