pppd; frame with bad fcs,

pppd; frame with bad fcs,

Post by J?rg Jendere » Mon, 28 Jul 1997 04:00:00



i am using
pppd version 2.2 patch level 0
linux kernel version :2.0.30

log facility
kernel.info

i have started ppp with

/usr/sbin/pppd /dev/cua2 debug kdebug 1 ipcp-accept-remote ipcp-accept-local -ipx-protocol defaultroute crtscts lock modem noipdefault -as 0 netmask 255.255.255.0 mtu 1500 connect /etc/ppp/callnumber X3DT0,0228-692064 0.0.0.0:0.0.0.0

and i get messages like:

Jul 26 19:42:12 mini kernel: ppp: frame with bad fcs, excess = 3828
Jul 26 19:42:13 mini kernel: ppp: frame with bad fcs, excess = 3e64
Jul 26 19:51:29 mini kernel: ppp: frame with bad fcs, excess = 2c7d

what does this mean ? or is this normal?

would be pleased if anyone can give me some tips and hints.

please answere by email . i seldom read this group because
i use an slow and expensive slip account via modem.

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pppd; frame with bad fcs,

Post by carl.. » Tue, 29 Jul 1997 04:00:00



Quote:> /usr/sbin/pppd /dev/cua2 debug kdebug 1 ipcp-accept-remote ipcp-accept-local -ipx-protocol defaultroute crtscts lock modem noipdefault -as 0 netmask 255.255.255.0 mtu 1500 connect /etc/ppp/callnumber X3DT0,0228-692064 0.0.0.0:0.0.0.0

> and i get messages like:

> Jul 26 19:42:12 mini kernel: ppp: frame with bad fcs, excess = 3828
> Jul 26 19:42:13 mini kernel: ppp: frame with bad fcs, excess = 3e64
> Jul 26 19:51:29 mini kernel: ppp: frame with bad fcs, excess = 2c7d

> what does this mean ? or is this normal?

Bad FCS means that the received data are corrupt.  Generally, it's not
normal.  It could be, though, depending on the hardware being used.
(If you were running this over either V.110 or any type of non-error-
correcting modem, such as a V.21 link, then I'd expect to see such
errors.  If you're running it over a standard V.34 modem with error
correction or over V.120, then I wouldn't expect to see such errors.)

Try removing "-as 0".  If it starts working, then you've got a
transparency problem somewhere.  Perhaps one of the devices is
configured for XON/XOFF flow control.

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pppd; frame with bad fcs,

Post by Andre Bec » Wed, 30 Jul 1997 04:00:00




> > /usr/sbin/pppd /dev/cua2 debug kdebug 1 ipcp-accept-remote ipcp-accept-local -ipx-protocol defaultroute crtscts lock modem noipdefault -as 0 netmask 255.255.255.0 mtu 1500 connect /etc/ppp/callnumber X3DT0,0228-692064 0.0.0.0:0.0.0.0

> > and i get messages like:

> > Jul 26 19:42:12 mini kernel: ppp: frame with bad fcs, excess = 3828
> > Jul 26 19:42:13 mini kernel: ppp: frame with bad fcs, excess = 3e64
> > Jul 26 19:51:29 mini kernel: ppp: frame with bad fcs, excess = 2c7d

> > what does this mean ? or is this normal?

> Bad FCS means that the received data are corrupt.  Generally, it's not
> normal.  It could be, though, depending on the hardware being used.
> (If you were running this over either V.110 or any type of non-error-
> correcting modem, such as a V.21 link, then I'd expect to see such
> errors.  If you're running it over a standard V.34 modem with error
> correction or over V.120, then I wouldn't expect to see such errors.)

> Try removing "-as 0".  If it starts working, then you've got a
> transparency problem somewhere.  Perhaps one of the devices is
> configured for XON/XOFF flow control.

These were the more complicated reasons. The typical reason, however,
is typical PC trash hardware called serial i/o unit without a (working)
FIFO. Even with a working FIFO, one may get these "COM overruns" every
now and then, due to other PC trash hardware which blocks interrupts
for enormous times, namely EIDE in certain block modes. These problems
are quite seldom on Linux (compared to Windoze), but they can pop up.

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pppd; frame with bad fcs,

Post by Patrick Kl » Tue, 05 Aug 1997 04:00:00




Quote:>i am using
>pppd version 2.2 patch level 0
>linux kernel version :2.0.30

>log facility
>kernel.info

>i have started ppp with

>/usr/sbin/pppd /dev/cua2 debug kdebug 1 ipcp-accept-remote ipcp-accept-local
>>>-ipx-protocol defaultroute crtscts lock modem noipdefault -as 0 netmask
>>>255.255.255.0 mtu 1500 connect /etc/ppp/callnumber X3DT0,0228-692064
>>>0.0.0.0:0.0.0.0

>and i get messages like:

>Jul 26 19:42:12 mini kernel: ppp: frame with bad fcs, excess = 3828
>Jul 26 19:42:13 mini kernel: ppp: frame with bad fcs, excess = 3e64
>Jul 26 19:51:29 mini kernel: ppp: frame with bad fcs, excess = 2c7d

>what does this mean ? or is this normal?

>would be pleased if anyone can give me some tips and hints.

How much of PPP is working?  Are you getting any PPP packets across without
an error?  Or is the connection not really getting started?  Maybe you can
provide more of your log file showing the PPP debug messages while the link
is coming up?

FCS errors are not normal or typical.  They always indicate a problem.

From the values of the FCS "excess" (whatever that is), my first guess
would be that the peer machine isn't in PPP mode at all.  Every byte in
these "excess" codes are in the range of what you would call "displayable
ASCII" (0x38 = '8', 0x28 = '(', 0x3e = '>', 0x64 = 'd', 0x2c = ',', and
0x7d = '}').  Is it possible you need to build more of a chat script to
get the peer machine to accept your connection before it starts PPP on
it's side (i.e. you have to login to the other side)?
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