[asterisk-users] how are channels numbers assigned

Tzafrir Cohen tzafrir.cohen at xorcom.com
Tue Dec 13 09:26:06 CST 2016

On Thu, Dec 08, 2016 at 02:24:14PM -0200, Ethy H. Brito wrote:
> Hi All
> I have this system here where:
> # dahdi_hardware 
> pci:0000:07:04.0     wctdm24xxp+  d161:8005 Wildcard TDM410P
> pci:0000:07:09.0     wcte11xp+    e159:0001 Digium Wildcard TE110P T1/E1 Board
> channels are 
> 	0-31 for TE110P


> and
> 	32-35 for TDM410P
> I want to insert a new TE110P. 
> How will these new channels be assigned? 
> What is the dahdi_genconf logic for these assignments?

Your version of dahdi is 2.7.0, which is a bit of a shame. Slightly
newer versions introduced span assignment: you can specify in
/etc/dahdi/assigned_spans.conf to which span number and channel number
will be used by each device. dahdi_genconf can generate a default one
for you, but see also 'dahdi_span_assignment dump'. Which means you
would not depend on a specific modue loading order.

That aside, dahdi_genconf just uses whatever dahdi gives it. With
automatic span assignments, the order of spans (and channels) is set by
the order in which the kernel modules happened to load.

> Is there a way to force these assignments to prevent they to change if I
> insert/remove any card from the system?
> chan_dahdi.conf is a bit confusing to me.
> What makes the configuration for one channel be finished and start the
> configuration for the next channel?
> Would you point me any docs on this matter?

The best I have so far is the README of dahdi-tools. A copy of it is in

> Asterisk is 11.7.0
> Dahdi is 2.7.0
> Ubuntu 14.04.5 LTS

               Tzafrir Cohen
icq#16849755              jabber:tzafrir.cohen at xorcom.com
+972-50-7952406           mailto:tzafrir.cohen at xorcom.com

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