Re: 28.8K modem, pppd and Multiface III card

[The Terminator rAT <rat%nas.nasa.gov@localhost>]

Bruce Drake writes:
 > Are there any other experiences out there?  I wouldn't mind hearing from
 > you myself.

Here's a weird (well, maybe not so weird...) effect of PPP/A3000 serial...

I have an A3000/25 with 10M of ram, running the Jun 8 snapshot.  I'm using
an USR Sportster 28.8k (external) on the internal serial, and have my 
ppp config'd at 38400 baud.  I don't use any fancy compression (VJ, etc) 
other than the built-in compression on the modems.

I have been able to send 3 Meg files to the ISP's machines at 3.0KB/sec. 
I get slightly slower (~2.5KB) rates sending *to* the amiga, accompanied
by a few (~5-10) fifo overflow console messages.  This is ``normal'' 
behavior for this link.

I have found that FTP, telnet, ssh, even a 'getURL' program (that emulates
an HTTP browser's request to a server, and puts the response into a file)
work nominally.  Retransmits aren't bad, transfer rates are realistic,
etc, etc.

However, running Xdaniver and Mosaic2.7b4, I am unable to even load the
Yahoo! home page.  It appears that TCP loses, as I see periodic blinks of
the TX light, indicating retransmissions of packets.  I have left it for
half an hour to go shopping and come back to find it had managed to load
just under a kilobyte from the server.  It appears that every packet
transmitted generates at input or output errors and must be retransmitted
several times.  Interestingly, the request usually gets through fine -- 
it's only when the server attempts to respond that the PPP fails.

The interesting thing about this effect is that if I reconfigure PPP to 
run at 19200 baud, I get fairly impressive performance from Mosaic.  
Pages load right up, etc, etc.

        - add '38400' to /etc/ppp/options, kill and restart pppd

        - start Mosaic.  go to lunch.  come back -- it has loaded 512 bytes
                from the remote server (only 7 hops away!)

        - kill Mosaic

        - change '38400' to '19200' in /etc/ppp/options.  kill and 
                restart pppd

        - start Mosaic.  Watch as it happily loads any page I ask for...

I assume this is some weird interaction between X, Mosaic, and the serial 
port interrupts.  Anyone have speculations beyond this?

Cheers!

        -rAT

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