[H-GEN] Mail problems.......

[Robert Brockway]

On Tue, 23 Sep 1997, Anthony Towns wrote:

> Some things to check:
> 
> 	- Are you sure your modem initialisation string is right?
> 
> 	- Are you using a "sensible" computer<->modem bps rate?
> 		(setserial?)
> 
> (could someone who knows about these give an explanation of what
> constitutes "sensible" for both of these, btw?)

For a modem using hw compression, the computer modem speed should
be >= 4 times the modem bps rate.  for 28k8, use 115k, for 14k4 use 56k,
etc.

 
> 	- Can your ISP really cope with such a large MTU? Robert's
> 	  scripts uses a (somewhat low) value of 296, the default is

Ah, yes.  I have been using 296 for sometime, so it ended up as default
in the script.  I'll be changing this.

> 	  (I think) 1005, and that's also want Prentice (UQ)
> 	  recommends (I think). I'd try dropping it to ~500, at least.
> 	  (move it gradually back up once you get it working)

I thought alot of places were going 1500 for all modems connections,
but not sure what prenticeis doing, so this is probably right on the
money.
 
> 	- What is your MRU set to? Changing this _may_ affect the
> 	  error rate (my guess would be the smaller, the less that
> 	  errors will affect your throughput). 1500 has worked for me
> 	  quite pleasantly, although again Robert's script uses 296.

Easy to change.  find the references to 296 and change them to 1500 (there
are two of them on the same line - one for mtu anf one for mru).

> 	  (also, the smaller, the more that packets have to be split
> 	  and then put back together later, so given an error-free
> 	  link, bigger should be faster, up to a point)

I mostly had the smaller value for interactive use.  Since ppp links
resend errors over the modem line only (unlike slip) resends aren't the
serious problem they could be.

> Another hint is to add the argument "debug" to the pppd line, and look
> at what appears in /var/log/debug for anything useful. This might give
> you a clue as to when the RX errors are happening. 

Good idea.
Cheers,
	-Robert 

--Robert Brockway. Email: robert at zen.humbug.org.au, robert at icc.net.au
                          r.brockway at mailbox.uq.edu.au, robert at plugged.net.au
                   WWW:   http://www.humbug.org.au/~robert
                   President of HUMBUG (http://www.humbug.org.au)

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