Modem won't connect at full speed

[Don Lewis]

On 20 Aug, Lars Eighner wrote:
> On Tue, 19 Aug 2003, Don Lewis wrote:

> I set the port setup in minicom to 57600, and got this
> on connect:
> 
> 
> atdt4857440
> CONNECT 29333/ARQ/V90/LAPM/V42BIS
> 
> 
> and when I hung up the current settings looked like this:
> 
> ati4
> U.S. Robotics 56K Voice INT Settings...
> 
>    B0  E1  F1  L1  M0  Q0  V1  X4  Y0
>    BAUD=57600  PARITY=N  WORDLEN=8
>    DIAL=TONE    ON HOOK   CID=0

> changed to 115200 in mincom port setup and got:
> 
> atdt4857440
> CONNECT 34666/ARQ/V90/LAPM/V42BIS

> With 230400, it didn't change:
> 
> atdt4857440
> CONNECT 34666/ARQ/V90/LAPM/V42BIS
> 
> Forced &B=0 and got
> 
> AT&B0
> OK
> atdt4857440
> CONNECT 36000/ARQ/V90/LAPM/V42BIS
> 
> which I guess is some improvement, but doesn't account for the
> huge discrepancies in actual download times/rates
> I am getting.

The speed reported with the CONNECT message is the modem to modem speed,
which depends on the how well the modems are able to cope with the
conditions of the phone connection.  It is independent of the DTE speed
that you use to connect to the modem.  It seems to vary somewhat from
call to call in this case, and it is fast enough that it shouldn't be
what is limiting your speed.

The DTE speed reported by ATI4 seems to match the speed that you are
using to connect to the modem, so if you have the speed in ppp.conf
cranked up, it should not be the limiting factor.

> I saved to NVRAM and exited. I adjusted the connect speed in ppp.conf
> to 115200. I rebooted and when ppp came up, no joy.  Ppp.log
> looked much the same, but it doesn't log the whole CONNECT line.
> 
> I really think this is a software thing, since all went well when
> I had a linux partition and did ppp from linux.

I'm inclined to agree.

> As I said, someone solved this for me before, but my records of it
> got lost in deleting the linux partion and moving freebsd and my
> data to the big disk.   A frantic search of wetware dimly suggests
> that the previous solution involved adding a couple of lines to
> a file one of which included "nobsdcomp" but that file wasn't
> in /etc/ppp, but was someplace really weird - maybe something to
> do with kernel mod loading.  That solution worked in 4.x-STABLE
> but I am now running 5.0-x RELEASE.
> 

The bsdcomp option is documented in the pppd man page.  The nobsdcomp
option disables it.  It is probably not supported by your ISP, but the
ppp startup negotiations should take care of this.  Other things that
might cause problems are the other flavors of compression, Van Jacobson
style TCP/IP header compression, and asyncmap.

Your comment about kernel modules sounds like the netgraph ppp module.