Date: Sun, 24 Feb 2002 10:33:25 -0500 From: "Joe & Fhe Barbish" <barbish@a1poweruser.com> To: "Maren S. Leizaola" <maren@leizaola.com> Cc: "FBSDQ" <questions@FreeBSD.ORG>, "Rod Person" <roddierod@yahoo.com> Subject: RE: SQUEEEZING the most bandwidth out of a 33.6 modem Message-ID: <LPBBIGIAAKKEOEJOLEGOOEKICIAA.barbish@a1poweruser.com> In-Reply-To: <Pine.WNT.4.43.0202242102440.-408861@hades.leizaola.com>
next in thread | previous in thread | raw e-mail | index | archive | help
In the USA the Government regulates what the phone companies can do.
The line voltage of all phone service is specified by the FCC.
This basically limits the connections to max at 52000 on the
very best of line conditions.
The connection speed using a 56k enabled modem is a function of
phone line conditions and speed of PC (cpu mhz & bus mhz).
That being said, many people watch what the connection speed is
for each time they dial into their ISP. Because of line conditions
you do not connect at the same connection rate all the time.
You will get a spread of connection rates like 48000, 49666, 50660,
52000, most users will just hangup the call and dial again until
they get the rate they want. This can be automated at the modem
hardware level. Lets say you have been watching and 60% of the time
you connect at 49666 or better, but the rest of the time you
hangup and dial again. Well you can use the hays AT commands to tell
the modem hardware not accept any connection speeds less that 49666
and the modem will auto redial until the connection is above 49666.
I do this with my Zoom model 3049L modem. AT&F0 to set factory default
setting into current memory. ATS38=19 to set modem register 38 to a
value of 19, which for zoom modems means 50666, then AT&W0 to write
current config to saved conf0, and the AT&Y0 to tell the modem to load
saved conf0 at power up.
Word of caution, I had set the modem to 52000 and on bad weather days I
would get a lot of bad packets which had to be resent which slowed down
the response time. I backed down to 49666 and the response time became
better.
You will have to play with the s38 value until you find
one that works best for your normal line conditions.
One other note. Each manufacture of modems may have a different meaning
for the S38=values, so check out the hays commands for your modem.
-----Original Message-----
From: owner-freebsd-questions@FreeBSD.ORG
[mailto:owner-freebsd-questions@FreeBSD.ORG]On Behalf Of Maren S. Leizaola
Sent: Sunday, February 24, 2002 8:23 AM
To: Rod Person
Cc: FreeBSD Questions
Subject: Re: SQUEEEZING the most bandwidth out of a 33.6 modem
On Sat, 23 Feb 2002, Rod Person wrote:
| Hi All,
|
| I have a US Robotics Sportster 33.6 external modem (it flashable to 56k).
| I was wondering if anyone had tips, trick or suggested reading on how to
squeeze bandwidth out of this modem.
Rod,
One of the things I use to do here in HK with the USR Couriers
V-Everything. I ordered a private wire back to my office. A private wire
is circuit that is not connected to the PSTN, it is used to extend phone
lines which are in another location back into a PBX.
I would run the USR Couriers in leased line mode, so that as soon as
you power them up they hand shake. It was pretty stable. In raw data I
could get 90Kbit/s sustained (on HTML or files which would compress
heavily), don't expect to get these through puts as they were pretty much
lab conditions and sometimes I was able. In burst rates I could get
113Kbit/s. One thing to note is that these private wires have lower
latency here in Hong Kong than normal phone lines so data flowed faster.
I implemented several of these in some cases based on what two locations I
was connecting I would get circuits which had no loading or conditioning.
That means you could run digital Line Drivers and get 128Kbit/256Kbit
circuits on them and pay a rate of US$20/month for the circuit.
Anyway to answer you question here are some suggestions but are dependant
on you being able to control both sides of the link.
Upgrade it 56K and plug it into a PPP connection. Make sure have TCP
header compression enabled on both sides. See what IPCP and othe protocols
you can use.
Another thing that you might want to try is stac compression or one of
those link compression protocols, I am not sure what features do the
current PPP implementations have.
Another thing you could do is use and SSH based VPN tunnel to tunnel the
traffic over the link and then go onto the net, this assumes that the
remote end is connected to the net and has a reasonable size pipe. SSH has
some pretty good compression and I suspect you will be able to get more
throughput than the other suggestions.
Good luck!
Regards,
Maren.
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-questions" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?LPBBIGIAAKKEOEJOLEGOOEKICIAA.barbish>