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Re: U.S.ROBOTICS problem in FC4 & suse1



Marv is right, as usual: speed is the issue.
This has been discussed and understood years ago in a thread at the ILUG (Israel Linux Users Group).

I suggest starting from a copy (among many other places) at:
http://gnowledge.org/pipermail/linuxers/Week-of-Mon-20011022/028653.html

Read slowly and through the thread because the error usually occurs when the ISP cannot stand the speed of the user.

In Mohammed's case, my **guess** is that the link is so slow that the ISP often times out (waiting for a reply packet) before the user's reply reaches the ISP.

Mohammed's slow rate is indeed probably due to poor phone lines - which ALWAYS goes along with a high rate of transmission errors. This strongly suggests to reduce the MTU to its minimum value, which unfortunately depends on the ISP and also on the user's IPvx selection.

All of you will ;-( certainly enjoy finding out your own minimum MTU following item #9 at http://www.mdgx.com/newtip7.htm

If you now would ask yourself how to set the MTU, edit /etc/ppp/options and add or change the mtu line
mtu 576
and also (not mandatory, suggested)
mru 576

Setting the mru low will instruct the ISP to abstain from sending larger packets.

576 is usually quite safe but is just an example, as with IPv6 it is, I believe, 1280 bytes. 296 may be too short even for IPv5, I do not remember.

IP newbies: at given error rate, the longer the packet the higher the probably to receive it corrupted and therefore repeated. Make it small
when error rate is high. Make it large when the error rate is low.

Jacques [Marv: back to Haifa, just f.y.i.]

Marvin Stodolsky wrote:
Mohammed,

CONNECT 9600 is a very low speed, suggesting a poor phone line connection
 From "man pppd", error 17 is:
17     The PPP negotiation failed because serial loopback was detected.
I'm not erudite on exactly what this means, Jacques is much more
knowledge on these issues and may comment from Tel Aviv in his morning

Meanwhile look through his Post Install suggestions at:
http://linmodems.technion.ac.il

MarvS



On 9/6/06, Mohammed AlRuwaili <m2o3h8d7@yahoo.com> wrote:

Gentlemen,

I bought a new U.S.ROBOTICS Message modem 5668B.
First i tried to install it on FC4 but it could not
recognize the modem.
Then i tried to install it on SUSE10 and it is
recognized.
The problem is when i start dialing and getting the
connection which will stay for about 2 min then the
connection will get lost.
Here is the Kinternet log,

SuSE Meta pppd (smpppd-ifcfg), Version 1.59 on linux.
Status is: disconnected
trying to connect to smpppd
connect to smpppd
Status is: disconnected
Status is: connecting
pppd[0]: Plugin passwordfd.so loaded.
pppd[0]: --> WvDial: Internet dialer version 1.54.0
pppd[0]: --> Initializing modem.
pppd[0]: --> Sending: ATZ
pppd[0]: ATZ
pppd[0]: OK
pppd[0]: --> Sending: AT Q0 V1 E1 S0=0 &C1 &D2
+FCLASS=0
pppd[0]: AT Q0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
pppd[0]: OK
pppd[0]: --> Sending: ATM1
pppd[0]: ATM1
pppd[0]: OK
pppd[0]: --> Modem initialized.
pppd[0]: --> Sending: ATDT3660011
pppd[0]: --> Waiting for carrier.
pppd[0]: ATDT3660011
pppd[0]: CONNECT 9600/ARQ/V34/LAPM/V42BIS
pppd[0]: --> Carrier detected. Waiting for prompt.
pppd[0]: ~[7f]}#@!}!} } }$}-o~~[7f]}#@!}!}=}
}.}%}&}<D[04]R}!}$}%\R;~
pppd[0]: --> PPP negotiation detected.
pppd[0]: Serial connection established.
pppd[0]: Renamed interface ppp0 to modem0
pppd[0]: Using interface modem0
Status is: connecting
pppd[0]: Connect: modem0 <--> /dev/ttyUSB0
pppd[0]: Serial line is looped back.
pppd[0]: Connection terminated.
Status is: disconnecting
Status is: disconnected
pppd[0] died: Loopback detected (exit code 17

Also I tried to use kppp in suse10 but unfortunately
it did not work.
As i tried to configure the modem using kppp but it
failed with message
"Unable to create modem lock file"
It seems that kppp can not detect the modem ,also i
tried most of the options
in kppp but no avail.

Please help......


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