PPP: "frame with bad fcs" errors

PPP: "frame with bad fcs" errors

Post by Robert Sturro » Sun, 01 Nov 1998 04:00:00



Hi all.

We are experiencing some problems with our PPP connection to our local
ISP (which stay connected 7x24).  We keep getting spurts of messages
like this:

Oct 27 07:49:04 cambridge kernel: ppp: frame with bad fcs, excess = 10a6

... written out to the system messages file.  According to the
documentation, these messages should not occur once the link has been
established.

We are running RedHat-5.1, with ppp-2.3.3-6.  We have both "debug" and
"kdebug 7" enabled in /etc/ppp/options.  I'm not sure whether we have
a problem here or not (just line noise?).  Can anyone give an opinion
about whether the errors/dropped packets rate below is high or not?
Is 79/22306 packets (~ 0.35%) dropped a problem?

cambridge$ uptime
  1:32pm  up 1 day,  4:42,  3 users,  load average: 0.00, 0.00, 0.00

cambridge$ cat /proc/net/dev
Inter-|   Receive                  |  Transmit
 face |packets errs drop fifo frame|packets errs drop fifo colls carrier
    lo:   9660    0    0    0    0     9660    0    0    0     0    0
  eth0: 135967    0    0    0    0   424656    0    0    0  1092    0
  ppp0:  22306   79   79    0    0    25351    0    0    0     0    0

cambridge$ pppstats
      IN   PACK VJCOMP  VJUNC  VJERR  |      OUT   PACK VJCOMP  VJUNC NON-VJ
 8968250  22306  12678   1939      0  |  3175491  25351  12375   1881  11095

We have had one remote site report a problem sending us some mail (a large
attachment), but other than that the link seems to perform ok ...

TIA.

/r.

 
 
 

PPP: "frame with bad fcs" errors

Post by Paul Thomps » Fri, 06 Nov 1998 04:00:00


This is not uncommon when using an external ISDN TA running 128k
and a 16550A UART serial port.  You will need the newer model
uart which can handle faster baud rates. (16650A is it?)

It's probably not a problem with ISDN, just an indication that you're
not receiving the full bandwidth.  On a regular modem I have seen these
messages accompanied by a retrain or other drop in performance, which
could be more serious.

You didn't mention your communications hardware....

Paul



Quote:> Hi all.

> We are experiencing some problems with our PPP connection to our local
> ISP (which stay connected 7x24).  We keep getting spurts of messages
> like this:

> Oct 27 07:49:04 cambridge kernel: ppp: frame with bad fcs, excess = 10a6

> ... written out to the system messages file.  According to the
> documentation, these messages should not occur once the link has been
> established.

> We are running RedHat-5.1, with ppp-2.3.3-6.  We have both "debug" and
> "kdebug 7" enabled in /etc/ppp/options.  I'm not sure whether we have
> a problem here or not (just line noise?).  Can anyone give an opinion
> about whether the errors/dropped packets rate below is high or not?
> Is 79/22306 packets (~ 0.35%) dropped a problem?

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