Initial Connect Speed Issues
Help! My 56K modem connects at
33.6 or less!
Even if I don't connect at 56K, I'm
guaranteed 33.6, right?
I'm connecting at 38400, 57600, or
115200. Or am I?
How can I get my modem to report the
true connect speed?
What are typical connect speeds for
56K modems?
Is initial connect speed all it's
cracked up to be?
What's the command for connection
speed and stats on my K56flex?
What's the command for connection
speed and stats on my USR?
What's a good way to test actual modem
performance? (FTP)
Help! My 56K modem connects at 33.6 or less!
Treat this as a troubleshooting matrix. Go through all of
these steps, and you will have a better than 90% chance of
solving your problems with slow connects.
|
THE OBVIOUS STUFF
We hate to ask, but you did check the obvious
things, right?
|
- Make sure that you and your Internet service provider
use the same 56K protocols. 56K requires that both ends
have 56K modems, and they both have to use the same kind
of 56K technology (x2, K56flex, or V.90). Despite what
you may have heard, V.90 is not the same as x2 or
K56flex. It is a third and distinct 56K protocol. Your
ISP will be able to tell you which protocol they
use.
- Some Internet service providers have separate phone
numbers for 56K. Make sure you're calling the right
number.
|
THE EASY ANSWERS
Things that are easy to try even if you don't
know much about computers. Don't skip this section,
because these fixes often work.
|
- If there is a telephone, answering machine, etc.,
plugged into the back of the modem, unplug it from the
back of the modem. The modem is supposed to ignore
devices plugged into it when it is online, but that is
not always the case.
- Try disconnecting additional telephony devices (fax,
phones, answering machines, alarm systems, etc.) from the
phone line, even if they're in a different room.
I've heard from readers whose connect speed jumped 10K
when they unplugged a fax machine or cordless phone in
another room.
- Also try running the phone line directly from the
back of the modem to the wall, without passing through
surge suppressors, splitters, phone line extenders, etc.
This is a basic and useful step in modem
troubleshooting.
|
MODERATELY DIFFICULT ANSWERS
These require slightly more computer skill.
If you don't know how to use a terminal program,
click on the links for help.
|
- DO NOT SKIP THIS NEXT STEP. It's always a good idea
to check the firmware
page to see if there is a more recent firmware
version available. Many people's problems have
disappeared once they installed a new version of the
firmware.
- Visit the inits
and drivers page to see if there is an init string or
better yet a driver for your modem. If there is, download
and install it. The inits and drivers page includes
installation instructions.
- If your modem supports more than one 56K protocol,
you may want to tell it which protocol (V.90, x2, or
K56flex) it should use. The commands are listed on the
interoperability page.
- It's possible there is an incompatibility between
your modem and your ISP's modems. You might try dialing
into some other local ISPs. You don't have to join or do
anything after you connect: just see how fast you can
connect to their modems.
- If this is a Rockwell-based K56flex modem, issue an
ATI3 command in a terminal
program. If the version number includes the letters
"DSP", click here. If the
version is 0.5 something, and your Internet service
provider uses K56flex Livingston Portmasters, click
here. If the version is 1.0 something, you should try
adding S202=32 to your init string.
- If this is a Lucent-based K56flex modem, issue an
ATI3 command in a terminal
program. The firmware version should be at least
4.06, and higher versions are better. Click
here for more information.
|
OR MAYBE IT'S YOUR PHONE LINE
I was hoping it wouldn't come to this, but it
may not be your modem or inside phone lines at
all.
|
It may be that the phone lines in your immediate
neighborhood don't support 56K
As explained in the Basics section of the 56K Primer,
multiple
digital/analog conversions will prevent the use of 56K
technology and limit your modem to V.34 speeds (a maximum of
33.6K).
"It's not my phone lines. I know they support 56K"
OK, how do you know your phone lines support 56K?
3Com's
line test is not guaranteed. It can tell you that your
phone line supports 56K when in fact it doesn't, and vice
versa. Don't put all of your faith in it. If you must use
the test line, 3Com recommends calling it multiple times
(ten times, say). On some calls it may say your line
supports 56K and on other calls it may say the opposite.
The fact that your modem can connect at 56K speeds to a
long distance number is no guarantee that the same is true
of local numbers, and vice versa. Long distance calls may be
routed through telephone circuits which are significantly
better or significantly worse than the local circuits used
to connect to your ISP.
How to find out for sure if your phone lines support
56K
This is the only reliable way I know of to test your
phone lines: borrow a known good 56K modem and try it with
your phone lines. By "known good 56K modem," I mean a modem
that has connected at speeds higher than 33.6. Remember that
connects speeds of 38400, 57600, and 115200 aren't true
connect speeds, so they don't count.
If it's an internal modem, have your friend bring the
whole computer to your house. In fact, it's easier that way,
because his computer will already be configured for his
modem. Let him use your monitor, keyboard, and mouse so he
won't have to cart them over to your house.
If you can only borrow the modem, be sure to get the
disks that came with the modem so you can install the
drivers for that modem. You'll have to install the modem and
drivers. Be sure to select the modem in your dialing
software (such as Windows 95 Dial-Up Networking or Apple's
PPP for Open Transport). Instructions are on the Inits
and Drivers page.
Once his modem is at your house, call his ISP. How fast
is the connection? You can also try calling your ISP, if
your ISP and your friend's modem use the same 56K protocol
(x2, K56flex, or V.90).
More about multiple digital/analog conversions, and
what to do about them
Office PBX systems generally create an extra A/D
conversion. How do you know if you're on a PBX? If you have
to dial a number (usually 9 in the U.S.) to dial an outside
line, you're on a PBX. If your phone has its own extension,
you're on a PBX. The solution in that case is to plug the
modem into a direct outside line. The office fax machine is
usually dialed into a direct outside line, so try that.
The phone lines outside of your building may have
equipment that introduces extra A/D conversions.
Non-integrated SLCs (subscriber line concentrators) are one
source. If that's the case, there's little you can do except
to call the phone company and complain. Before you get your
hopes up, be aware that the phone company is generally not
sympathetic, and only guarantees speeds of 9600 baud or so
(the exact answer will vary from telco to telco). It is
worth a shot, though, and some people have managed to get
their phone company to re-route the lines.
Even if I don't connect at 56K, I'm
guaranteed 33.6, right?
No. In fact, even if you and your ISP were using 33.6
modems, you still wouldn't be guaranteed 33.6 connects. Few
people get 33.6 connects. A large number get 28800 or 31200
connects, but many people only connect at 26400, 24000, or
even slower. The phone lines in some areas simply can't
support higher speeds.
If you'd like to try improving the speed, make sure you
have the latest firmware
and drivers/settings
files. Also, try passing the phone line directly from
the back of the modem to the phone outlet on the wall.
Passing the phone line through surge protectors, phones,
answering machines, etc., has sometimes been responsible for
slow connects.
Again, though, your phone lines may simply not support
higher speeds.
I'm connecting at 38400, 57600, or 115200.
Or am I?
No. Those speeds are computer-to-modem speeds (AKA DTE
speeds or port speeds) that you set in your software. What
you want to know is the modem-to-modem speed (AKA connect
speed or DCE speed).
Your <-DTE Speed-> Your <-DCE Speed-> Remote
Computer Modem Modem
How can I get my modem to report the true connect
speed?
For Windows 95 Dial-Up Networking and Apple's PPP for
Open Transport
You must install the correct drivers for your modem. For
instance, you would need to the correct .inf file for
Windows 95 Dial-Up Networking, or the correct CCL file for
Apple's PPP for Open Transport. The drivers interpret the
result code from the connection and translate it into a
connect speed. Without the driver, you won't get an accurate
connect speed. These may have been included on a disk with
the modem. If not, check the 56K.COM
Inits and Drivers page, which has links to downloadable
drivers and instructions for installing the drivers.
If you have the correct driver/settings file and you
still don't get the true connect speed, add one of the init
strings below to your init
string.
For other programs that do not use driver files
According to 3Com/U.S. Robotics, any init string that
includes AT&F1 should report the true connect speed.
For most Rockwell-based 28.8 and K56flex units, the
command is W2. (For Rockwell-based PCI modems, the command
is MR=2.) However, several commands can override W2,
including the S95 commands and the &Q commands. If W2
doesn't have the desired effect, you might try adding S95=0
or S95=1 to the init string.
What are typical connect speeds for 56K modems?
As with 33.6 modems, your results will depend heavily on
your phone lines. To see what kind of performance other
people are getting, see the performance
survey. Typically, 42-46K for K56flex and anywhere from
44-52K for x2 is good performance. Some people are getting
better results, some are getting worse.
Is initial connect speed all it's cracked up to be?
Initial connect speed is a convenient benchmark, but it
can be deceiving. V.34 and 56K modems can and do shift their
speeds up and down during the course of the call to respond
to changing line conditions. Some modems connect very
aggressively at high speeds, but are then forced to lower
their speed to a more stable level. Others may connect
conservatively and upshift.
The best test is to download a compressed file with FTP.
For help with getting accurate results, see the section
below on FTP.
What's the command for connection speed and stats on my
K56flex?
Lucent-based K56flex modems
After disconnecting, issue an ATI11 command in your
terminal program.
Rockwell-based K56flex modems
After disconnecting, issue an AT&V1 command in your
terminal program.
These are some example results. TX is the transmit (upload)
speed. RX is the receive (download) speed.
AT&V1
TERMINATION REASON.......... LOCAL REQUEST
LAST TX data rate........... 31200 BPS
HIGHEST TX data rate........ 31200 BPS
LAST RX data rate........... 46000 BPS
HIGHEST RX data rate........ 50000 BPS
Error correction PROTOCOL... LAPM
Data COMPRESSION............ V42Bis
Line QUALITY................ 127
Receive LEVEL............... 014
Highest SPX Receive State... 00
Highest SPX Transmit State.. 00
EQM Sum Value............... 00A2
RBS Pattern detected........ 00
Data Rate Dropped in kbps... 00
Digital Pad Detected........ None
What's the command for connection speed and stats on my
USR?
After disconnecting, issue an ATI6 and ATI11 in your
terminal program.
These are some example results. Note that the ATI6 Speed
line shows the highest download/upload connect speeds. The
ATI11 command shows the number of upshifts and downshifts
for receive (RX) and send (TX).
ATI6:
Chars sent 580 Chars Received 49642
Chars lost 0
Octets sent 360 Octets Received 26533
Blocks sent 191 Blocks Received 805
Blocks resent 0
Retrains Requested 0 Retrains Granted 0
Line Reversals 0 Blers 1
Link Timeouts 0 Link Naks 0
Data Compression V42BIS 2048/32
Equalization Long
Fallback Enabled
Protocol LAPM SREJ 128/15
Speed 46666/31200
Last Call 00:04:34
Disconnect Reason is Escape code
ATI11:
USRobotics Courier V.Everything Link Diagnostics...
Modulation x2/V.34+
Carrier Freq ( Hz ) NONE/1920
Symbol Rate 8000/3200
Trellis Code NONE/64S-4D
Nonlinear Encoding NONE/ON
Precoding NONE/OFF
Shaping OFF/ON
Preemphasis Index NONE/0
Recv/Xmit Level (-dBm) 15.7/12.2
SNR ( dB ) 61.5
Near Echo Loss ( dB ) 10.2
Far Echo Loss ( dB )
Roundtrip Delay (msec) 26
Timing Offset ( ppm) -1406
Carrier Offset ( ppm) 68
RX Upshifts 0
RX Downshifts 1
TX Speedshifts 0
x2 Status 0000; 0000-0000-0001-0000-0000-0000; 00,00 0031;03
What's a good way to test actual modem performance? (FTP
downloads)
If done correctly, file downloads are a good way to test
modem performance. The trick is to make sure you're really
testing the modem's raw transfer rate, and not some other
factor that you're not aware of. Here are some guidelines
for download testing:
1. USE AN FTP PROGRAM
Web browsers often lie about download rates. FTP is more
reliable. Note that some FTP programs reports download
speeds in Kilobits per second (Kbps), while others use
Kilobytes per second (KBps). To convert, multiply Kilobytes
per second by 10 (eight bits plus the start bit and stop
bit). (V.42 error correction strips out the start bit and
stop bit, but adds other overhead, so multiplying by nine
may be more accurate.) A valid alternative to FTP is a
terminal program that supports Zmodem.
2. DOWNLOAD A PRE-COMPRESSED .ZIP OR .SIT FILE
If the file you download isn't compressed, hardware data
compression in the modem will kick in, leading to erroneous
results. Different file types compress to different degrees,
so if you download a Microsoft Word file and I download a
QuickTime movie, there's no way to compare the results. Use
.zip (PKZip/WinZip) or .sit (StuffIt) files for your tests.
Some file formats (GIF, JPEG, QuickTime, etc.) offer some
compression, but can sometimes be compressed further by
hardware protocols.
3. DOWNLOAD A FILE THAT'S AT LEAST 200K
A file size of at least 200K will minimize the effects of
TCP/IP slow start.
4. DOWNLOAD FROM YOUR LOCAL FTP SERVER OR UNIX
DIRECTORY
A local server is one that's on your system, not on the
other side of the Internet. If you download a file from
across the Internet, you're testing your ISP's connectivity
to the Internet just as much as you're testing your modem.
Most ISPs have FTP sites at ftp.ispname.com. If you're on
AOL, for instance, go to ftp.aol.com to download files.
There will usually be a directory called pub that contains
downloadable files.
5. DOWNLOAD DURING OFF HOURS
To eliminate congestion issues, download early in the
morning or late at night.
|
