[asterisk-dev] MASTER CLOCK selection for ZAP/DAHDI span does not work (always 1st active span...)

Felipe Bergo fbergo at gmail.com
Tue Nov 25 06:25:18 CST 2008

In my experience with digium boards, after a red and/or yellow alarm the
driver ignores the previous span setting and synchronizes the span to
whatever clock first became available when the alarm condition is gone,
usually the board's internal clock (and in most cases we want the board to
sync to the remote clock in these situations).

If you run /usr/sbin/dahdi_cfg, it'll probably reset the sync source to the
proper setting of /etc/dahdi/system.conf.

In my (non-asterisk) applications, I monitor the span for alarms and issue a
DAHDI_SPANCONFIG ioctl after any red/yellow alarms are cleared (else the
driver syncs to the wrong source regardless of system.conf or previous

I don't know whether the semantics of alarm recovery are meant to work like
this (design decision), but working around it is somewhat trivial from the
programmer's point of view.

-- Felipe Bergo
Labcom Sistemas, Campinas, SP, Brazil

On Tue, Nov 25, 2008 at 9:57 AM, Anton VG <anton.vazir at gmail.com> wrote:

> 2008/11/25 Tzafrir Cohen <tzafrir.cohen at xorcom.com>:
> > On Tue, Nov 25, 2008 at 11:23:50AM +0500, Anton wrote:
> >> On Monday 24 November 2008 23:20, Tzafrir Cohen wrote:
> >> >
> >> > What did you expect here to happen?
> >>
> >> Hm, I'm not sure what you mean. But shouldn't zaptel dahdi
> >> select the proper device to be a master clock instead first
> >> available?
> >
> > How would you define "proper"?
> >
> > BTW: it is "span" rather than "device".
> Tzafrir,
> If you have ever used over than a single E1 span link, what you surely
> did, you must know that one of the links becomes a master clock for
> asterisk through zaptel, what you also surely do. I'm surprised why
> you ask such a questions, since I definitely know you know what I
> mean, and it's YOUR code (written by you), which actually shows what
> device is an actual MASTER for the system. but MASTER is seems to be
> not selectable, regardless ZAP/DAHDI config settings, and that's why I
> do ask if I do miss something, since it's looks definitely
> misbehaving.
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