[asterisk-users] PRI Splitter

[Michael Graves]

On Mon, 01 Sep 2008 09:20:32 -0500, Karl Fife wrote:

>> > Look at this brand new failover device:
>> >
>> > http://www.rhinoequipment.com/1portfail.html
>> >
>> > http://www.rhinoequipment.com/Single%20Port%20Failover%20Datasheet%201-22-2008.pdf
>> 
>> 
>> Interesting !
>> I didn't know this one.
>> What happens if the PC supporting this card is powered off ?
>> Do you have an idea of its price ?
>
>This is an important point:  Not only does the loss of PC power NOT
>present a problem, is the main DESIGN element.  If the PC/Server powers
>off, the relays naturally de-energize, which by design, PASSES the
>service to the failover port (to the port connected to your spare server
>or analog devices).  
>
>While by itself that would be a pretty good design, there would be a
>vulnerability, because of course it's possible to have Asterisk crash
>while the server is still happily powered on.  Therefore the Rhino
>failover device incorporates another design element:  If you choose, you
>can enable its watchdog system.  If asterisk stops responding to a
>periodic message, It knows that Asterisk is down, and fails over your
>services to the other server or analog devices EVEN IF the power is
>still on at the main server!
>
>-Karl

In the broadcast business we call this "two-stage fault tolerant
bypass." 

Hardware relays trip in the event of loss of power. A software based
watchdog trips if the application under test becomes unresponsive.

Often the watchdog doesn't trip the relays as being mechanical that
creates a switching glitch. They trip a logic switch so that the signal
through the device stays clean into bypass.

It's also worth testing to see how the card boots up. Is it clean on
restart? That is, can you reset it without interrupting your traffic?

Michael

--
Michael Graves
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http://blog.mgraves.org
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