[asterisk-users] HDLC Bad FCS (8) on Primary D-channel

[Olivier]

2010/6/11 Karsten Wemheuer <kwem at gmx.de>

> Hi Olivier,
>
> Am Freitag, den 11.06.2010, 14:27 +0200 schrieb Olivier:
> >
> >
> > 2010/6/11 Karsten Wemheuer <kwem at gmx.de>
> >         Hi,
> >
> >         Am Freitag, den 11.06.2010, 11:54 +0100 schrieb Gareth Blades:
> >         > Olivier wrote:
> >         > > Hello,
> >         > >
> >         > > I've got a running system in which logs are full of
> >         messages such as:
> >         > > [Jun 10 07:24:14] NOTICE[2414] chan_dahdi.c: PRI got
> >         event: HDLC Bad FCS
> >         > > (8) on Primary D-channel of span 2
> >         > >
> >         > > The strange thing is those messages are coming from a
> >         single span.
> >         > >
> >         > > My setup is :
> >         > >
> >         > > Asterisk 1.6.1.18
> >         > > Junghanns OctoBRI
> >         > > with wcb4xxp driver
> >         > > libpri 1.4.10.2
> >         > > dahdi 2.3.0
> >         > > 3 BRI lines in PtMP mode
> >         > >
> >         > >
> >         > > What does this "PRI got event: HDLC Bad FCS (8) on Primary
> >         D-channel of
> >         > > span 2" roughly mean ?
> >         > > Why could it happen on a single port and not on the
> >         others ?
> >         > >
> >         > > Regards
> >         > Basically it means that one of the messages it received on
> >         the PRI D
> >         > channel failed the checksum.
> >         >
> >         > I take it that in your span command you have 'crc4' or
> >         similar specified
> >         > as an option for all of your spans?
> >         >
> >         > If thats the case its probably a faulty port on the card,
> >         cable, or a
> >         > card in the local telephone exchange,
> >
> >
> >         AFAIK CRC4 is for PRI only. The setup of Olivier is BRI in
> >         PTmP mode.
> >         Many providers drive Layer 1 down in case of inactivity. Maybe
> >         the
> >         driver has a problem with such lines.
> >
> > Would that explain why only a single port is hit ?
>
> No, except if this port is configured differently from the others (on
> the provider site)...
>
> >
> > This port is the 2nd and the dialing pattern is DAHDI/g1 which means
> > "start with channel 1 on span 1, then channel 2 on span 1, then
> > channel 4 on span 2, ....".
> Ok, but dialing is Layer 3. You are observing layer 2 errors on the
> D-Channel (LAPD-protocol).
>
>
> > What I observed is that provider sends incoming calls alternatively to
> > each span :
> > if an inbound call comes through span 2 (channel 4 or 5), then the
> > provider would send the next one to span 3 (channel 7 or 8) if
> > available, etc ...
> To my experience a provider do not send incoming calls to different
> ports on PTmP lines. Each line gets his own numbers, there is no
> overflow (at least in germany). But again: Your original problem are
> layer 2 errors. Reasons could be:
> - line broken
> - port broken
> - driver do not handle layer 1 down in case of inactivity
>
> > I'll try to swap cables and see if messages are "moving" from span 2
> > to another span.
>
> Good idea.
>

Tough I swaped cables between ports 2 and 3, I still can read messages such
as :
chan_dahdi.c: PRI got event: HDLC Bad FCS (8) on Primary D-channel of span 2

My thoughts are this happens because port 2 is somehow broken.
So I changed my config to use port 1, 3 and 4 instead of 1,2 and 3, and see
if things are improving.
I'll report here what I'll find.


>
> Have a nice weekend.
>
> Karsten
>
>
>
>
> --
> _____________________________________________________________________
> -- Bandwidth and Colocation Provided by http://www.api-digital.com --
> New to Asterisk? Join us for a live introductory webinar every Thurs:
>               http://www.asterisk.org/hello
>
> asterisk-users mailing list
> To UNSUBSCRIBE or update options visit:
>   http://lists.digium.com/mailman/listinfo/asterisk-users
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.digium.com/pipermail/asterisk-users/attachments/20100615/14908ad1/attachment.htm