Dialup connection 1/3rd slower than in XP

English Network/Internet
1

I’m a newbie to openSUSE11, and there is no broadband where I live. The modem is an Actiontec EX560LKU with serial or USB connection. I’m using the USB because the one serial is already in use.

Speed tests on the internet show that WinXP downloads a 150Kb file in ~25 secs. or 5.96 Kbps. The same test with openSUSE 11 shows it takes ~170 secs. to download the same file or 0.88 Kbps. Firefox with IPv6 disabled was used for both tests, and IPv6 was disabled in openSUSE during the install. Both WinXP and openSUSE are connecting at 50-52 Kbps.

After research, I’ve modified the MTU and MRU to appropriate values for dialup. In /etc/ppp/options I’ve added two lines after the line “crtstcs”:
MTU 576
MRU 512

When the modem is connected /sbin/ifconfig shows the following for modem0:
UP POINTOPOINT RUNNING NOARP MULTICAST MTU:512 Metric:1

The init string is slightly different between the defaults in WinXP and openSUSE 11:
WinXP: AT &F E0 &C1 &D2 V1 S0=0\V1
openSUSE: AT Q0 V1 E1 S0=0 &C1 &D2 +FCLASS=0

I thought that changing from the openSUSE to the WinXP init string might solve the problem. YaST2 recognizes the modem (/dev/ttyUSB0). However, I can’t get it to maintain changes after clicking all the way through to “finish”. Each time I return the modem baud rate is back to the highest rate (400000) instead of the 57600 I changed it to, and the init string is back to the openSUSE original from the WinXP substitution.

Sooo, I modified /etc/wvdial.conf. Changed baud to 57600 and the init string to the WinXP version. After connecting to the Internet, I examined the KInternet log, which showed wvdial used the openSUSE init string instead of the WinXP version substituted in wvdial.conf. Checking through YaST, the baud was back to 4000000 and the openSUSE init string was still there.

QUESTIONS:
1.) Why does ifconfig show MTU 512 when /etc/ppp/options has MTU 576?
2.) How do I get YaST and/or wvdial to accept the baud rate and init string changes?

TIA,
Mark Z.

2

Forgot to ask Question 3.
3.) Is there something else I should try in order to get faster downloads in openSUSE11?

3

Success at last. With some additional digging in the logs and man pages, and a little experimentation, I figured out I was modifying the wrong file. I had been working on wvdial.conf, but I should have been modifying smpppd-ifcfg.

Once that nut was cracked, everything else was a piece of cake. First change was the connection speed from 4000000 Kbps to 115600 Kbps. Then compared speed results of the default openSUSE init string against the default from DUN in WinXP. Turns out using the WinXP string in SUSE is much faster, just about the same as using it in WinXP. Both now download a 150 Kb test file in about 25 secs.

I don’t know why YaST doesn’t write the changes even though the rigmarole at “Finish” says it’s making the mods. At this point, though, it doesn’t matter.