[asterisk-users] Fully utilise all PRIs in a DAHDI group

[Tony Mountifield]

In article <201210171813.45334.raju at linux-delhi.org>,
Raj Mathur (राठ  माथॠर) <raju at linux-delhi.org> wrote:
> Hi,
> 
> Our client has DAHDI groups with 4 PRIs in each group (one 4-port 
> interface per group), up to 6 groups per server.  When we dial, we can 
> specify the group to be used for dialling, and our dial plan 
> automatically distributes calls over multiple servers and multiple 
> groups within a server.
> 
> The way Asterisk dials by default is to use the lowest-numbered free 
> line in a group to place a call.  This is technically fine.  However, 
> what it means for our client is that the first couple of PRIs in a group 
> tend to get the bulk of calls, the other two remain more-or-less 
> unutilised.  This is a problem, since there are call commitments to the 
> Telco for each PRI line.  The Telco tends to get all soggy and hard to 
> light if some of the PRIs are used way below committed call levels.
> 
> One solution is to group at the individual PRI level, so the load 
> balancing automatically takes care of fair utilisation of each PRI.  
> However, for various reasons we'd prefer not to do this.
> 
> Another solution would be if Asterisk could choose a random (or LRU or 
> LCU or round-robin or any other scheme) PRI within a group when 
> dialling.  Any roughly fair way to distribute calls to PRIs within a 
> DAHDI group would be fine.  Is there some way to achieve this?
> 
> Asterisk 1.8.8 on Debian Squeeze.

Instead of dialling using DAHDI/g1/123456789, you can try using
DAHDI/r1/123456789 to make Asterisk use the channels in round-robin
order instead of always choosing the lowest free channel.

See http://www.voip-info.org/wiki/view/Asterisk+ZAP+channels (I could not
find comparable information on the Asterisk WIKI at https://wiki.asterisk.org).

Cheers
Tony
-- 
Tony Mountifield
Work: tony at softins.co.uk - http://www.softins.co.uk
Play: tony at mountifield.org - http://tony.mountifield.org