Modem Speed

The serial interface (UART chip) on a PC handles many different internal data transfer rates. The highest rate it handles is 115200. This means that applications can communicate with the _modem_ at that speed, but not necessarily what's outside the modem.

The rates of 46000, 36000 etc. are normal and you're not going to see higher connection rates with Linux. I'm not familiar with wvdial but you could configure your modem's initialization string (e.g. AT&F1 for factory defaults on a US Robotics) to have the modem itself report the negotiated rate.

You could do a 'wget' to a fast site to see what speed you can actually download at.

By the way, it is still possible to see extremely fast data transfers (e.g. 115200) with a modem connection. The way it works is: let's say the modem is connected with another modem at 48000 but receiving some kind of highly compressable text. If the modem/link has built in compression support, that data could be decompressed at your computer and actually fed to your application at a tremendous rate.

Jem Berkes

There's a FCC regulation limiting line radiation. An analog modem operating at speeds beyond about 53 kb/s causes line radiation that exceeds that limit.

That's for V.90 modulation and V.42bis compression. For V.92 the up and down speeds can both be configured for 48 kb/s - according to a USR paper. From another source, V.92 has V.44 compression which, for normal web browsing, "out-performed V.42(bis) by up to 60%".

And on rare occasions the speed may exceed 11520 B/s, nominally the greatest rate at which the usual 115200 b/s PC serial device can transfer data between it and pppd. The modem to ISP DCE data transfer rate at 53 kb/s is only 6625 B/s, not counting PPP frame and networking protocols' overhead.

Clifford Kite

Look in your modem manual for the AT command, in the old Hayes command set ATW1s95=47 would cause the modem to report initial DCE connect speed (and other things as well). Add the chat option “REPORT CONNECT” and the pppd option updetach (or nodetach to be able to control-c pppd) to get it sent to the terminal.

REPORT CONNECT may not work for an old version of chat and -detach may be needed in an old verision of pppd. Chat comes with the pppd source package, and the latest pppd source package (2.4.0) can be obtained via ftp at linuxcare.com.au in /pub/ppp.

Clifford Kite

Add the setting ATW2 or ATW1 to your modem settings. And in your chat script, just before you dial add the lines

This will write the modem-to-modem (carrier) speed to /etc/ppp/connect-errors (I think that's the file it goes to). You can look in there after it connects. However, if your modem re-negotiates the link, then your modem-to-modem speed may change.

Bob Glover

for a GUI display under X, try pload

http://www.engr.utk.edu/~mdsmith/pload/

or pppstats, came with my ppp-2.3.5, from

ftp://cs.anu.edu.au/pub/software/ppp/

Alan J. Wylie

You need to have chat be invoked with the -v option, and it will then log everything via syslog (ie, go to /var/log/messages by default). Under the RedHat 5.2 scripts, if your /etc/sysconfig/ifcfg-ppp0 file contains:

it will pass "debug" to pppd to allow it to log interesting tidbits once the connection is up, and to pass "-v" to chat to debug the initial session. Linuxconf under 5.2 doesn't seem to have special support for this, but the older netcfg does support it with a button under the communication panel.

You also need to make sure your modem reports the modem speed when connected. This is modem specific, and you will need to read the friendly manual. For my Courier, the commands are:

where:

I think AT&W will then set those options in NVRAM so that ATZ won't reset them — but I don't have the FM in front me. You also might want to make sure, and add the appropriate commands to the chat script).

Note, the chat script will only show you the initial modem speed. Many modems can change speed during the connection to adapt to local line conditions.

I also put ATI6I11 in my chat script before dialing, so that I get a copy of the modem statistics for the last call dumped in my syslog. This way, I can look at it if I suspect getting bad connections and look at retransmits and BLERs. I live out in a fairly rural area west of Boston, and there have been several times when I needed to call the phone company due to excessive noise on my modem line, and back when I used ISPs to connect, I ran into two incompetent ISPs that seemed to have extended problems on their end (and I would manually need to change which POP I connected to).

I believe that X-Isp also includes connection speed. The web page is at:

Michael Meissner @ Cygnus Solutions (Massachusetts office)

Below is an awk script I wrote that I use in /etc/ppp/ip-up

Make sure you enter the proper path to your xmessage binary. Mine is /usr/X11/bin/ — yours may differ.

To make this script work you need to modify your chat script to add a report log. The following will work:

This tells chat to report connection information in /var/log/modem. The awk script uses this file to display connection speed and time in a xmessage. The message will disappear after 10 seconds.

Depending on your modem settings, it will either report speed in DTE or DCE speed. DTE speed is the speed at which the PC sends and receives data from the modem and is usually reported as 115,200. DCE speed is the speed at which the modems speak to each other. This speed is usually something less than the maximum advertised modem speed, e.g., 56k or 33.6k. It is the DCE speed that most people are interested in.

If your modem is reporting DTE speed and you want DCE instead, you need to issue an AT command to reset your modem. The command to report DCE speed is usually W2. An easy way to ensure your modem is reporting DCE speed is to add the W2 command in the chat script. For example:

could be changed to:

Hope this helps.

John Riggs

Then I ran kdevmon on the KDE desktop on the server so as to monitor the ppp0 connection. Instead of reporting just the connect speed it does a running computation of speed every so many millieconds and reports a top, current and average speed - which should give you an indiaction of what is going on with the dialup - speeds can drop and rise as the connection ages, get it at: http://apps.freshmeat.net/homepage/947602271/

Rootman

It's not a 100% accurate, but for conventional purposes, Microsoft has set up a page to track your throughput. Any browser should be able to be used to test your line speed. It's at: http://computingcentral.msn.com/topics/bandwidth/speedtest.asp

Peter Chung

The fastest connection you can get between any 2 analog modems (V.34) on perfect normal phone lines is 33.6K. Due to line quality 24-28K may be the best you can do. It takes special digital hardware and digital line directly from the phone company to run a 56K (V.90 or V.92) server.

I often see people wanting to dialin to their home or office to use their DSL or cable connection, but it would be faster to simply use a dialup ISP. My boss does that simply because he is to tight to get an ISP (I hung a 33.6K modem we already had on a Cisco router).

David Efflandt

s a bit low, but 56k modems can only work with a digital— direct to line modems on the other side. Two 5k modems can only connect at max of 33K.

Bill Unruh

In the chat-ppp script add the following lines:

(I've added mine after the ABORT lines. This will tell your box-modem speed (CONNECT) and your modem-isp speed (CARRIER).

Gav.

Make sure you use the correct modem commands to make your modem report connection speed when it connects then adjust your dialing script (the one specified by pppd's connect option) to extract the speed from the connect message. Something like the following should work:

Bill Hay

In my ppp-on-dialer script, I have:

which makes any lines with ATDT, CONNECT, tele, test-finch or finch be logged into /var/log/chat. During connection, I can tail -f /var/log/chat and see what my initial connection speed was. You cannot monitor your *current* connection speed as all but professional modems can only do this inline usint at&v1 or similar. You can of course check for re-trains etc. after your connection has terminated.

Alex Butcher

From the btinternet.linux FAQ:

Colin

Whether or not this will help you, I have no idea… but I thought I'd offer it since it made a huge difference in my Linux ppp connection.

With kppp I went in and added some ppp arguments to set the MTU and MRU.

This is easy to do in Win9X with various shareware programs, (less easy to edit the registry to do it, but also possible) and it's pretty easy to do with kppp by just adding the "mtu 576" and "mru 576" entries under ppp arguments in kppp.

Now, whether those numbers are ideal for your connection I have no idea. They work great on mine… BUT, every ISP is different. The numbers can run from 296-1500… and only experimentation will figure out what's best for you.

Heck, those arguments might not work at ALL on your pc… but they've dramatically sped up my connection, to the point where Linux is now noticeably quicker downloading than Win98 (as it ought to be!) Before those arguments, it worked, but much slower. Transfer rates on the same file improved from the 1.0 k/sec range to 3.8-4.0 k/sec, although connection speed was identical. No stringent testing, though, so don't beat me up over those numbers…

Worth a shot, anyway.

Jase

I actually tweaked a few thing (actually I am not sure what exactly it was that finally worked - maybe a combination of a few) but now my modem screams along seemingly faster than my WINNT config. Regarding some of these "connection monitoring tools" like the WindowMaker docable network monitor apps,kppp tools, etc. How reliable are they? I ask because under WINNT 4.0 I am very suspect of both the connection rate and the download speeds NT is telling me I am getting. Is it fair to compare the Linux tools (if so which ones) to the WINNT DUN monitors?

Maybe I am being picky here but I am very interested in connection speeds and download speeds with Linux (RedHat 5.2) compared to WINNT 4.0. And also connection speeds under Linux depending if I use kppp, WvDial, or just command line. I am trying to get some "comparable" network monitoring tools for both NT and Linux so I am not comparing apples to oranges.

no_modem

Netscape downloads give an indication (average) at the bottom of the window.

There's a "pppload" which shows a plot of instantaneous Snd/Rcv rates.

There are some other network load monitors in

http://www.aa.net/~swear/pedia/networking.html and http://www.aa.net/~swear/pedia/sys-admin.html

Gary Momarison

The 384/128 guarantee is only from your home PC to where your connection at the CO finally hooks into their internet pipeline. Beyond that, you truly are at the mercy of the rest of the internet which Pacbell has no control over.

However, I am assuming that you did try a variety of different web sites to test your connection from. From a good site, I get over 1,100,000 bps down and over 120K up. This is with SWBell's lowest cost DSL service, which I understand is identical to PacBell's. From a bad site, I can crawl on my hands and knees with the best of them.

The best web site for testing I've found is http://speedtest.mybc.com.

One possibility is that your copper line has some bridge taps or other impediments which should be removed. However, your speeds are slow enough that I wonder how you passed the line test to get the service in the first place! Fully 50% of the people I personally know who have signed up for ADSL locally have been rejected as having inadequate connections.

Testing line quality is something that is impossible for you to do yourself directly, but you can conduct a polite campaign of contacting them and following up to see if they will do a better test of your line and correct whatever defects they find. I understand this is a slow process, however.