asterisk users - Jan 2011 - Call queues on load-balanced asterisks

Hello,

I have been asked to implement the following design:

Load-balanced Kamailio servers handling registrations and routing. 
Load-balanced asterisk feature servers handling voicemail and other things
Kamailio cannot do. Plus several load-balanced gateways, but they are not
relevant to my question.

All this is working fine.

I've now been asked to start implementing calling queues, and my question is
this:
How can I implement the same queue on multiple Asterisk servers?

Let's say that 10 people call the same queue. These calls would then
currently be distributed 5 to Asterisk A and 5 to Asterisk B. How can I make
Asterisk A respect the 5 people queued on the other server and vice versa?

Will the customer need to change their design to make the feature servers
master-slave with failover instead of load-balanced?

Mvh
Pan
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Hello Pan,

You can user DB for this just make real time configuration of Queue and make
all asterisk server connected to Same DB if more load then use replication
for different server on DB, also So that Quque name should be same for all
server and asterisk can call same agent.

you didnot mentioned that which purpose youwere use queue other wise i can
give answer in better way.

regards
Dhaval

On Fri, Jan 7, 2011 at 5:08 PM, Pan B. Christensen <pan at ibidium.no>
wrote:
>  Hello,
>
> I have been asked to implement the following design:
>
> Load-balanced Kamailio servers handling registrations and routing.
> Load-balanced asterisk feature servers handling voicemail and other things
> Kamailio cannot do. Plus several load-balanced gateways, but they are not
> relevant to my question.
>
> All this is working fine.
>
> I've now been asked to start implementing calling queues, and my
question
> is this:
> How can I implement the same queue on multiple Asterisk servers?
>
> Let's say that 10 people call the same queue. These calls would then
> currently be distributed 5 to Asterisk A and 5 to Asterisk B. How can I
make
> Asterisk A respect the 5 people queued on the other server and vice versa?
>
> Will the customer need to change their design to make the feature servers
> master-slave with failover instead of load-balanced?
>
> Mvh
> Pan
>
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Hello Dhaval (and others),

As far as I can tell, realtime queue will not solve my problem. I can statically
define the same queue with the same members on two machines as well. I was
planning to use realtime anyway. The issue is the actual queueing of the
incoming calls.

Let?s say I define the queue "IT-support" with members Local/100 and
Local/101 on both machines. The first call comes in and is distributed by
Kamailio to Asterisk A, and answered by 100. The next call comes in to Asterisk
B, and is answered by 101. At this point, both members are busy. Call 3 now
comes in and is sent to Asterisk A, where it waits for a free member. Call 4
comes in and is also sent to Asterisk A, as is Call 5. Then call 6 is sent to
Asterisk B. At this point 100 finishes his call and becomes free. Which call is
delivered to 100? As far as I can tell, that?s a 50/50 chance between call 3 and
call 6. This is not correct behaviour! Call 6 should wait until calls 3, 4 and 5
(from the other server) have all been delivered.

In the example above: When call 3 comes in, Asterisk A may even try to deliver
it to 101, who gets call waiting indication. He will now have two simultaneous
calls from the same queue!

I have not found any way to share information about calls waiting in the queue,
wait times, member states and so on between the two servers.

Unless you guys know of a way, I think I'm going to have to ask the customer
to change their design to master-slave (with failover) instead of load-balanced.

With kind regards,
Pan
> Hello Pan,
> 
> You can user DB for this just make real time configuration of Queue and
make
> all asterisk server connected to Same DB if more load then use replication
> for different server on DB, also So that Quque name should be same for all
> server and asterisk can call same agent.
> 
> you didnot mentioned that which purpose youwere use queue other wise i can
> give answer in better way.
> 
> regards
> Dhaval
> 
> On Fri, Jan 7, 2011 at 5:08 PM, Pan B. Christensen <pan at
ibidium.no> wrote:
>
>>  Hello,
>>
>> I have been asked to implement the following design:
>>
>> Load-balanced Kamailio servers handling registrations and routing.
>> Load-balanced asterisk feature servers handling voicemail and other
things
>> Kamailio cannot do. Plus several load-balanced gateways, but they are
not
>> relevant to my question.
>>
>> All this is working fine.
>>
>> I've now been asked to start implementing calling queues, and my
question
>> is this:
>> How can I implement the same queue on multiple Asterisk servers?
>>
>> Let's say that 10 people call the same queue. These calls would
then
>> currently be distributed 5 to Asterisk A and 5 to Asterisk B. How can I
make
>> Asterisk A respect the 5 people queued on the other server and vice
versa?
>>
>> Will the customer need to change their design to make the feature
servers
>> master-slave with failover instead of load-balanced?
>>
>> Mvh
>> Pan
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Hi Pan & Dhaval,

We have implemented a FastAGI based queue with Erlang for a inbound call
center, and call this new application as FlexQueue.
All calls distributed on multiple asterisk boxes go through and are
controlled by that same remote fastagi server.

It can routing calls to any destination, by any business rules. It don't
rely on the db for agent/call status store & query. 
It's event driven and dict based agent/call store & query, with very
good
performance, and low cpu power consumption.

I think for your requirement, app_queue could not fulfill that. 

Best Regards,

Thomas Liu
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--------------

 
> Hello Dhaval (and others),
> 
> As far as I can tell, realtime queue will not solve my problem. I can
statically
> define the same queue with the same members on two machines as well. I was
planning
> to use realtime anyway. The issue is the actual queueing of the incoming
calls.
> 
> Let?s say I define the queue "IT-support" with members Local/100
and
Local/101
> on both machines. The first call comes in and is distributed by Kamailio
to Asterisk
> A, and answered by 100. The next call comes in to Asterisk B, and is
answered by
> 101. At this point, both members are busy. Call 3 now comes in and is sent
to Asterisk
> A, where it waits for a free member. Call 4 comes in and is also sent to
Asterisk
> A, as is Call 5. Then call 6 is sent to Asterisk B. At this point 100
finishes
> his call and becomes free. Which call is delivered to 100? As far as I can
tell,
> that?s a 50/50 chance between call 3 and call 6. This is not correct
behaviour!
> Call 6 should wait until calls 3, 4 and 5 (from the other server) have all
been
> delivered.
> 
> In the example above: When call 3 comes in, Asterisk A may even try to
deliver
> it to 101, who gets call waiting indication. He will now have two
simultaneous
> calls from the same queue!
> 
> I have not found any way to share information about calls waiting in the
queue,
> wait times, member states and so on between the two servers.
> 
> Unless you guys know of a way, I think I'm going to have to ask the
customer to
> change their design to master-slave (with failover) instead of
load-balanced.
> 
> With kind regards,
> Pan
> 
> > Hello Pan,
> >
> > You can user DB for this just make real time configuration of Queue
and
make
> > all asterisk server connected to Same DB if more load then use
replication
> > for different server on DB, also So that Quque name should be same for
all
> > server and asterisk can call same agent.
> >
> > you didnot mentioned that which purpose youwere use queue other wise i
can
> > give answer in better way.
> >
> > regards
> > Dhaval
> >
> > On Fri, Jan 7, 2011 at 5:08 PM, Pan B. Christensen <pan at
ibidium.no>
wrote:
> >
> >>  Hello,
> >>
> >> I have been asked to implement the following design:
> >>
> >> Load-balanced Kamailio servers handling registrations and routing.
> >> Load-balanced asterisk feature servers handling voicemail and
other
things
> >> Kamailio cannot do. Plus several load-balanced gateways, but they
are
not
> >> relevant to my question.
> >>
> >> All this is working fine.
> >>
> >> I've now been asked to start implementing calling queues, and
my
question
> >> is this:
> >> How can I implement the same queue on multiple Asterisk servers?
> >>
> >> Let's say that 10 people call the same queue. These calls
would then
> >> currently be distributed 5 to Asterisk A and 5 to Asterisk B. How
can I
make
> >> Asterisk A respect the 5 people queued on the other server and
vice
versa?
> >>
> >> Will the customer need to change their design to make the feature
servers
> >> master-slave with failover instead of load-balanced?
> >>
> >> Mvh
> >> Pan