[asterisk-users] ISDN PRIs and taking a server down formaintenance - blocking issue

[Matt]

That does sound like what is happening.. Telco knows channel 1-23 are not
busy (so far as they are concerned), however.. so far as you are concerned,
they are busy.. so telco sends the call down... but the equipment doesn't
take it.

I would *think* the Telco could keep trying channels down the hunt group,
but maybe not?  We have, in the past, seen this issue with our dial-up modem
banks.. especially if I would take one offline.   However, it is not a big
enough issue (i.e. we don't take things down that often) for me to look into
it fully.

On Thu, Feb 14, 2008 at 4:07 PM, Don Kelly <dk at donkelly.biz> wrote:

>  I think the problem is that the telco presents the call on a specific
> channel, then zaptel tells it that the channel is busy.
>
>
>
> We need to be able to tell the telco that each unused channel on a given
> span is unavailable, and it will determine that the others are in use and
> will present the call on a channel on another span.
>
>
>
> A rather ugly work-around (since Andrew seems to have lots of channels
> available, and one would assume that maintenance of this nature would occur
> during slow periods) would be to make calls to a DID in the same trunk group
> on all "idle" channels on the span shutting down then, when all channels on
> the span are "in use" and none of them are doing anything useful, take the
> span down hard so the telco will divert all calls to another span.
>
>   --Don
>
> Don Kelly
> PCF Corp
> Real Support for your Virtual Office TM
> 651 842-1000
> 888 Don Kell(y)
> 651 842-1001 fax
>
>   ------------------------------
>
> *From:* asterisk-users-bounces at lists.digium.com [mailto:
> asterisk-users-bounces at lists.digium.com] *On Behalf Of *Matt
> *Sent:* Thursday, February 14, 2008 2:28 PM
> *To:* Asterisk Users Mailing List - Non-Commercial Discussion
> *Subject:* Re: [asterisk-users] ISDN PRIs and taking a server down
> formaintenance - blocking issue
>
>
>
> Honestly.. this sounds like a telco issue.    I understand what the other
> person is saying about the PRI still being technically up... BUT... if the
> channel is BUSY/BLOCKED/WHATEVER, the Telco should be forwarding the call to
> the next available channel, which they clearly are not doing.
>
> On Thu, Feb 14, 2008 at 8:29 AM, Andrew Smith <andrews at meadeplc.com>
> wrote:
>
> Hi Tim,
>
> Imagine the scenario where we had 10x Asterisk servers, with calls
> presenting sequentially starting from the first server, then server two,
> etc.
>
>
>
> If we took down the first server for maintenance with 'asterisk -rx stop
> gracefully' we then will block all incoming calls to all servers as our
> telco will simply relay the BUSY back to the caller. If there are a number
> of calls on the first server that continue for another 20 minutes, then all
> inbounds are blocked for that period of time.
>
>
>
> We are finding at present we have to look at the calls on the server and
> make a decision if we are busy to simply reboot the server and hence lose
> calls. Not ideal but then we don't end up blocking our inbounds.
>
> What I was hoping to do was find a way to cause the telco to present the
> call to the next ISDN30 and therefore would allow us to cleanly take down an
> Asterisk server for maintenance without causing this issue. In a sense to
> put the ISDN30 into alarm mode while still continuing the active calls.
>
>
>
> Do you know if this is at all possible, even if we considered patching
> zaptel to add this functionality or does the telco rely on the entire PRI
> being in alarm before it presents the call to the next ISDN30 ? This would
> allow us to run maintenance on our servers during busy periods without
> causing disruption, and would be an excellent feature.
>
> Many thanks,
>
> Andrew
>
>
>  ------------------------------
>
> *From:* asterisk-users-bounces at lists.digium.com [mailto:
> asterisk-users-bounces at lists.digium.com] *On Behalf Of *Tim Nelson
> *Sent:* 13 February 2008 18:12
> *To:* Asterisk Users Mailing List - Non-Commercial Discussion
> *Cc:* asterisk-users at lists.digium.com
> *Subject:* Re: [asterisk-users] ISDN PRIs and taking a server down for
> maintenance - blocking issue
>
> Even if * is shutdown, zaptel is still running and your ISDN channels are
> still technically up. Shutting down zaptel should close the channels and put
> those circuits into alarm mode.
>
> Tim Nelson
> Systems/Network Support
> Rockbochs Inc.
> (218)727-4332
>
> ----- Original Message -----
> From: "Andrew Smith" <andrews at meadeplc.com>
> To: asterisk-users at lists.digium.com
> Sent: Wednesday, February 13, 2008 12:03:51 PM (GMT-0600) America/Chicago
> Subject: [asterisk-users] ISDN PRIs and taking a server down for
> maintenance - blocking issue
>
> Hi there,
>
>
>
> I currently have multiple Asterisk servers using Sangoma A104d Quad ISDN
> E1s.
>
>
> Basically our telco is presenting calls in order of the ISDNs on our
> servers.
>
>
>
> SERVER1=1,2,3,4
> SERVER2=5,6,7,8
>
>
>
> We have redundancy in that if SERVER1 is shutdown then each ISDN PRI is in
> alarm and the calls will then presented to PRIs 5,6,7,8 on SERVER2.
>
> If I have to take SERVER1 offline for maintenance (asterisk -rx shutdown
> gracefully) any incoming calls receive a BUSY tone.
>
> What I would like to know is if there is anyway to get around this and not
> send a BUSY back to our callers and somehow allow our telco to present calls
> immediately to SERVER2.
>
> Anyone have any ideas or are we stuck with this behaviour until the calls
> drop to 0 and Asterisk shuts down ?
>
> Thanks,
> Andrew
>
>
>
>
>
>
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